Development of a Disease-specific Health-related Quality of Life Questionnaire for Sleep Apnea W. WARD FLEMONS and MARLENE A. REIMER Faculties of Medicine and Nursing, University of Calgary, Calgary, Alberta, Canada

The Calgary Sleep Apnea Quality of Life Index (SAQLI) was developed to record key elements of the disease that are important to patients. All items felt to influence the quality of life of these patients were identified. Final questionnaire items were selected by interviewing 113 patients with sleep apnea and 50 snorers who rated each item on whether it was a problem and the importance of it to their overall quality of life. Items for the final questionnaire were selected based on the rank order of the frequency 3 importance product. The rank ordering was similar across strata of disease severity and between sexes. The Calgary SAQLI has 35 questions organized into four domains: daily functioning, social interactions, emotional functioning, and symptoms. A fifth domain, treatment-related symptoms, can be added for clinical intervention trials to record the possible negative impacts of treatment. The SAQLI has a high degree of internal consistency, face validity as judged by content experts and patients, and construct validity as shown by its positive correlations with the SF-36 and the improvement in scores in patients successfully completing a 4-wk trial of continuous positive airway pressure. It includes items shown to be important to patients with sleep apnea and is designed as a measure of outcome in clinical trials in sleep apnea. Flemons WW, Reimer MA. Development of a disease-specific health-related quality of life questionnaire for sleep apnea. AM J RESPIR CRIT CARE MED 1998;158:494–503.

Sleep apnea is a disorder characterized by repetitive partial or complete occlusions of the upper airway during sleep. Common nocturnal effects include hypoxemia, arousals from sleep, and brief increases in blood pressure (1, 2). Common daytime effects include excessive sleepiness, irritability, decreased concentration and memory, decreased energy, and depressive symptoms (3, 4). The most widely used therapy is nasally applied continuous positive airway pressure (CPAP), which decreases sleepiness and improves neurocognitive function and vigilance (5). Questionnaires to assess severity of daytime sleepiness have been developed, but they have not taken into account the impact of this symptom on patients’ lives (6). No questionnaires have been developed to assess the specific health-related quality of life issues that are important to patients with sleep apnea. Generic health measures such as the Nottingham Health Profile (NHP) (7) and the Medical Outcomes Study 36-Item Short-Form Health Survey (SF-36) (8) have been used in patients with sleep apnea, but they may not detect more subtle effects of the disease on quality of life and were not constructed to evaluate within-subject change after treatment (5, 9, 10). We therefore developed and tested a disease-specific instrument to evaluate health-related quality of life in patients

with sleep apnea for use in clinical trials. We followed published guidelines that have been used to construct health-related quality of life scales in other disease states (11–15).

METHODS Item Generation Five approaches were used to identify the many ways that sleep apnea might contribute to impairment of quality of life that were important to patients suffering from this disorder. First, we conducted a comprehensive review of the sleep apnea literature. Second, we drew on our clinical experience and prior research with hundreds of patients with sleep apnea during the previous 8 yr. Third, we sought the opinions of eight sleep apnea content experts from across North America. Fourth, we used five focus groups involving approximately 50 patients with sleep apnea and their partners to discuss the impact of sleep apnea and its treatment on their quality of life. Fifth, we conducted semistructured interviews, lasting approximately 2 h each, with 40 patients with sleep apnea, most of whom had been treated with nasal continuous positive airway pressure (CPAP). These interviews included openended questions about all possible aspects of a patient’s life that might be adversely affected from having (or having had) sleep apnea. From content analysis based on all of these approaches a list of 133 items likely to be important to patients with sleep apnea was developed. This list included 24 symptoms associated with treatment, primarily with CPAP, that might have some adverse impact on quality of life.

(Received in original form December 4, 1997 and in revised form February 25, 1998)

Item Selection

Supported by grants from the Alberta Lung Association and the Foothills Hospital.

The purpose of this phase was to determine which of the 133 items were most commonly experienced and were most important to patients with sleep apnea. We identified the last 300 patients to undergo polysomnography in our sleep laboratory, and then excluded patients in whom a disorder other than sleep apnea had been diagnosed or who lived outside of Calgary. A random sample of the remaining pa-

Correspondence and requests for reprints should be addressed to Dr. W. Ward Flemons, Alberta Lung Association Sleep Disorders Centre, Foothills Hospital, 1403 29th Street N.W., Calgary, AB, T2N 2T9 Canada. Am J Respir Crit Care Med Vol 158. pp 494–503, 1998 Internet address: www.atsjournals.org

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Flemons and Reimer: Sleep Apnea Quality of Life Index tients was asked to participate. The 133-item questionnaire was administered individually to these 100 patients by a trained interviewer. Because women were not adequately represented, we interviewed 13 additional, randomly selected, women from the patient list. We also administered the questionnaire to 50 patients referred by their physician to an otolaryngologist for a primary complaint of snoring. Of the 133 questions in the questionnaire, all patients were asked three questions about 109 items that pertained to quality of life issues that may have been as a result of them having sleep apnea and/or snoring: (1) was it a problem for them? (yes/no); (2) if it was a problem how important was it to their quality of life? (five-point scale ranging from “not very important” [zero] to “extremely important” [five]); (3) if they had undergone treatment, how much did it improve? Patients with sleep apnea who had undergone treatment were asked an additional 24 questions about treatment-related symptoms. For each item the frequency that respondents answered “yes, it was a problem” was recorded (frequency). Next the mean importance score for each item was determined (importance), and finally the product of these two numbers (frequency 3 importance) was calculated. Patients who had undergone treatment for their sleep apnea were also asked how much improvement they had experienced in a particular problem after treatment. Patterns of response were analyzed to determine if there were differences according to sex (unpaired t tests) or clinical sleep apnea severity (analysis of variance). A rating of each patient’s severity of sleep apnea was assigned by physicians experienced in assessing patients with sleep apnea after reviewing the patient’s chart and based on a combination of the apneahypopnea index, degree of oxygen desaturation and extent of selfreported daytime symptoms.

Questionnaire Construction and Testing Items with a high frequency 3 importance rating were selected for inclusion in the final questionnaire, the Calgary Sleep Apnea Quality of Life Index (SAQLI). When it appeared that two questions were probing for similar types of information we determined the concordance rate for the response that both items either were or were not a problem. If the concordance rate was greater than 85% then the questions were combined, or the one that appeared to us to be the inferior question was dropped. Items were eliminated from the final questionnaire if most patients reported that it had not improved after a therapeutic intervention. The items that were chosen through this process to be included in the Calgary SAQLI were organized into four domains: A. Daily Functioning (11 items): B. Social Interactions (13 items): C. Emotional Functioning (11 items): D. Symptoms (five items). An additional domain, E, entitled Treatment-related Symptoms (five items) was added for use when some active therapy such as surgery, CPAP, or a dental appliance has been tried. Provision was made in Domains D and E for patients to select and rate the five symptoms most relevant to their experience. Patients were also given an opportunity to add other symptoms to this list. The questionnaire was designed for administration by a trained interviewer using Likert scales with seven response options (see APPENDIX). Color coded cards, as used in similar types of quality of life questionnaires (12, 15), were used so that subjects did not have to remember the response options. The questionnaire was sent to six clinical experts from across North America, distinct from the first group of experts, who were asked to comment on its sensibility, clarity, and comprehensiveness. The SAQLI was then tested in 24 patients with newly diagnosed sleep apnea who were about to start a home trial of CPAP to determine: (1) that the questions and instructions were understood and made sense to the patient, (2) that a complete range of responses on the Likert scales was used, (3) the degree of correlation with the SF36, (4) the degree of internal consistency (reliability), and (5) that the items were responsive to change after a 4-wk trial of CPAP. The SF36 was chosen for assessment of convergent validity because it is widely accepted as a generic measure of quality of life, and some of the scales such as Vitality and Physical Functioning may be particularly sensitive to the symptoms of sleep apnea and improvement with CPAP (10). CPAP compliance was monitored covertly in most patients with hour timers that were activated only when the machine was generat-

ing a pressure within 2 cm H2O of the set pressure. All patients had a minimum 4-wk home trial of CPAP (Healthdyne Tranquility Quest 7300; Healthdyne, Marietta, GA); occasional patients had slightly longer trials because of scheduling difficulties. Patients who were found not to be compliant with therapy were given an additional 2-wk trial. All patients initially had complete orientation to CPAP from trained respiratory therapists and had easy access to them for any difficulties they had with CPAP. Compliance was defined as greater than 3.5 h average use per night, which has been previously shown to be the average use by patients with sleep apnea (16, 17), for at least 2 wk prior to their final assessment. Prior to starting CPAP the patients completed the SF-36 and the SAQLI. At the completion of the CPAP trial subjects completed the SF-36 and a global rating of change for each SAQLI item. Subjects were asked if they had experienced a change in the item. If it had not changed the item was given a score of zero. If it had changed they were asked if it had improved or worsened. The degree of improvement or worsening was assessed with a seven-item Likert scale that ranged from “hardly any improvement (worsening)” to a “a very large improvement (worsening).” A rating of 2, “a little improvement (worsening),” or more was taken to indicate a clinically significant change (17, 18). Negative numbers indicated worsening and positive numbers indicated improvement, so in total there were 15 response options (27 to 17). An average rating of change was calculated for each of the domains A through D of the SAQLI. Domain E from the SAQLI, Treatment-related Symptoms, was included with this testing. After the administration of the questionnaire respondents were asked to identify any questions they had difficulty understanding or made them feel uncomfortable. Suggestions for revision were sought for any questions identified as problematic. Patient feedback led to only minor revisions. Internal consistency of the SAQLI was evaluated by calculating Cronbach’s alpha. The research was approved by the University of Calgary Conjoint Medical Research Ethics Board, and all subjects signed informed consent forms. Subjects who had their CPAP compliance monitored covertly signed a poststudy consent form that informed them of this monitoring and requested they allow their data to be used in the final analysis. No patients refused this request.

RESULTS Baseline characteristics of the 113 patients with sleep apnea and 50 snorers who completed the 133-item questionnaire and the 24 patients selected to test the SAQLI are listed in Table 1. As expected for a referral population to a sleep laboratory, patients tended to be middle-aged men. The vast majority of the patients had regular sleeping partners, and there was a good spectrum of disease severity. Of the 113 patients with sleep apnea, 80% had attempted some type of therapy; 42% reported regular CPAP use for a median of 6 mo (interquartile range, 1 to 14 mo). The highest scoring items from the initial questionnaire are shown in Table 2. The highest scores were typically related to problems with alertness, concentration, and the feeling that most activities required an extraordinary effort to accomplish. A majority of patients reported that their snoring or sleep apnea was contributing to significant problems in their relationships. Patients also reported many effects on their mood that were probably secondary to chronic sleep deprivation. Some questions had a very high concordance rate with other questions. For example, 90 patients indicated that being told by their partner that their snoring was bothersome/irritating to them was a problem. Of those 90 patients, 87 also indicated that being told by their partner that their snoring disturbs their partner’s sleep was a problem. The overall concordance rate for the percentage of respondents who indicated that the item either was or was not a problem for them between these two questions was very high (96%). Therefore, only one of the questions was included in the final version of the SAQLI. Other items, for example “concerns patients had about

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TABLE 1 CHARACTERISTICS OF 113 PATIENTS WITH SLEEP APNEA, 50 SNORERS, AND 24 TEST SUBJECTS Characteristics Mean age, yr (SD) Sex Male, n (%) Female, n (%) Regular sleeping partners Yes, n (%) No, n (%) Sleep apnea/snoring severity* Mild, n (%) Moderate, n (%) Severe, n (%) Treatment None, n (%) Weight loss, n (%) Dental splint, n (%) Surgery, n (%) CPAP ever, n (%) CPAP regular use, n (%)

Patients with Sleep Apnea (n 5 113)

Snorers (n 5 50)

Test Subjects (n 5 24)

49.5 (10.6)

44.9 (9.9)

52.3 (11.5)

83 (73) 30 (27)

37 (74) 13 (26)

20 (83) 4 (17)

97 (86) 16 (14)

41 (82) 9 (18)

22 (92) 2 (8)

54 (48) 35 (31) 24 (21)

5 (10) 17 (34) 20 (40)

10 (42) 7 (29) 7 (29)

20 (18) 6 (5) 6 (5) 18 (16) 63 (56) 48 (42)

0 0 0 0 24 (100) 15 (63)†

* Sleep apnea severity as rated by experienced physicians; snoring severity as rated by the patients. † Fifteen patients had covertly monitored compliance data demonstrating they used the machine on average 4 h per night during the previous 2 wk.

their physical appearance,” had a reasonably high frequency 3 importance product but were excluded from the SAQLI because almost all patients reported that it did not improve after therapy. With few exceptions there was very little difference in the order of the frequency 3 importance product between men and women and between the three levels of sleep apnea clinical severity (Table 3). The only exception to this was in the domain Social Interactions where there was general agreement among the first four items, but the last four items in that domain were more variable. There was very good agreement between snorers and patients with sleep apnea in their ranking of items selected for most of the domains. Although the rank order of items was similar between different groups, the mean frequency 3 importance scores were higher in women than in men (Table 4). There were also differences between snorers and patients with sleep apnea and between different levels of sleep apnea severity. As expected, snorers had the lowest scores, and patients with severe sleep apnea had the highest scores. SAQLI Testing

Results from the SAQLI and SF-36 in 24 patients with sleep apnea prior to commencement of CPAP are shown in Table 5. The scores in each of the SAQLI domains and the total score range from 1 (poor quality of life) to 7 (excellent quality of life). The scores in each of the SF-36 domains and total score range from 0 (poor quality of life) to 100 (excellent quality of life). Symptom scores (Domain D) were clearly lower than the other domain scores (A, B, and C). There was a wide range of scores in these patients with no obvious floor or ceiling effects. Results from the SF-36 were below values reported for a normal population, especially in the domains of Role-Physical, and General Health, and Vitality. The correlation between the SAQLI and SF-36 total scores (r 5 0.21) was not statistically significant (p 5 0.30); there was a higher, statistically significant, correlation between the SAQLI total score and the Vitality domain of the SF-36 (r 5 0.45, p 5 0.03) (Figure 1). Twenty of these patients completed at least a 4-wk trial of CPAP using a machine capable of monitoring compliance. Of these, 15 patients were compliant with therapy. Their rating of change of each of the items in the SAQLI, summarized by

mean domain scores and the change (before–after) in SF-36 scores is shown in Table 6. The rating of change scores were greatest for symptoms and least for social functioning and emotional functioning. For each of the domains and the total score of the SAQLI rating of change, 33% or more of the patients reported being at least somewhat better (score of 3 or greater). In the symptoms domain, 75% of patients reported being at least somewhat better. When treatment-related scores (Domain E) were included in the calculation of total SAQLI rating of change score the total fell by 0.4. Treatment related symptoms were consistently rated less important to patients than the other items in domains A to D. The SF-36 domain scores that improved in patients who successfully used CPAP were role-physical, vitality, and roleemotional. Overall there was a reasonably high correlation between the SAQLI rating of change (total) and the change in total SF-36 score (r 5 0.60; p 5 0.018) as well as five of eight SF-36 domains: Vitality (r = 0.81; p = 0.0002), Mental Health (r 5 0.76; p 5 0.0009), General Health (r 5 0.69; p 5 0.005), Physical Functioning (r 5 0.61; p 5 0.02), and Social Functioning (r 5 0.51; p 5 0.05) (Figure 2). Internal consistency as measured by Cronbach’s alpha for the SAQLI total score was 0.92 and for each domain was: A, 0.88; B, 0.92; C, 0.92; D, 0.92.

DISCUSSION The development of the Calgary SAQLI was comprehensive and systematic so that all items that were potentially relevant to the lives of patients suffering from sleep apnea would be identified. We took advantage of published guidelines and recommendations for developing a disease-specific quality of life questionnaire that have been used successfully in developing indices in many other related disease states (12–15). The items included in the final version of the SAQLI were those that a random sample of patients with sleep apnea identified as important. We have demonstrated that although the mean frequency 3 importance product was different between men and women (Table 4), their ranking of items was extremely similar (Table 3), as in the Asthma Quality of Life Questionnaire (12). Thus, we believe the SAQLI is appropriate for all

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Flemons and Reimer: Sleep Apnea Quality of Life Index TABLE 2 ITEMS WITH THE HIGHEST FREQUENCY 3 MEAN IMPORTANCE PRODUCT IN 113 PATIENTS WITH SLEEP APNEA

Normal Daily Routine Having to push yourself to remain alert Decreased ability to concentrate Having to fight to stay awake Decreased ability to remember things A decrease in your motivation to do exercise and leisure-type activities Having to force yourself to go to work, school, etc. A tendency to give what energy you have to accomplish only work-related activities Difficulty getting home maintenance or chores done around the house A decrease in your ability to do exercise and leisure-type activities A loss of useful leisure time Adjusting your schedule to avoid activities because you might not be able to remain alert Social interactions Being told that your snoring disturbs your spouse’s or partner’s sleep Being told that your snoring was bothersome or irritating to your spouse or partner Less interest in socializing Wanting to be left alone A decrease in sexual intimacy A tendency to look for excuses for being tired An increase in the number of conflicts/arguments Having to sleep in separate bedrooms A need to make special sleeping arrangements when traveling A feeling of guilt about your relationship with family members Decreased involvement in family activities Emotional state Frustration Irritability A feeling of depression or being down Impatience A decreased ability to cope with everyday issues Anxiety or fear about what is wrong Being easily upset A tendency to become angry Self perceptions Perception of an actual or potential health problem because of your weight Perception of an actual or potential health problem because of shortness of breath Concerns about your physical appearance Symptoms Daytime Decreased energy Excessive fatigue Difficulty in staying awake while reading Ordinary activities require an extra effort to perform or complete Falling asleep if not stimulated or active Fighting the urge to fall asleep while driving Difficulty with a dry or sore mouth/throat upon awakening Difficulty in staying awake during theatre/lecture Difficulty in staying awake during movies Falling asleep at inappropriate times or places Difficulty in staying awake during a planned television show Nocturnal Waking up often (more than twice) during the night Restless sleep Concern about the times you stop breathing at night Waking up at night feeling like you were choking Difficulty returning to sleep if you wake up in the night Waking up more than once per night (on average) to void Treatment-related Discomfort from the nasal mask Excessive dryness of the nasal passage Air leakage from the nasal mask Marks and/or a rash on your face Waking up frequently during the night Nasal congestion or stuffiness Soreness in the nasal or throat passages Rhinnorhea (runny nose) Hardship in being able to pay for the treatment Complaints from your partner about the noise of CPAP Difficulty returning to sleep if you awaken Headaches

Frequency

Mean Importance

Frequency 3 Importance

73 78 71 66 65 58 53 56 50 45 37

3.21 3.00 3.22 3.18 3.21 3.25 3.45 3.24 3.42 3.24 3.19

234.3 234.0 228.6 209.9 208.7 188.5 182.9 181.4 171.0 145.8 118.0

80 79 58 50 41 39 38 41 40 36 39

2.96 2.95 3.13 3.04 3.24 3.28 3.28 3.02 3.00 3.22 2.95

236.8 233.1 181.5 152.0 132.8 127.9 124.6 123.8 120.0 115.9 115.1

66 70 64 56 53 54 50 45

3.30 3.10 3.33 3.10 3.17 3.09 3.05 3.04

217.8 217.0 213.1 173.6 168.0 166.9 152.5 136.8

71 43 42

3.10 3.35 3.26

220.1 144.1 136.9

80 71 78 65 61 58 66 51 50 46 48

3.28 3.47 2.93 3.18 3.10 2.94 2.41 3.03 2.77 2.96 2.45

262.4 246.4 228.5 206.7 189.1 170.5 159.1 154.5 138.5 136.2 117.6

77 69 52 50 41 48

3.06 3.17 3.22 3.02 3.46 2.65

235.6 218.7 167.4 151.0 141.9 127.2

45 48 47 36 30 34 31 30 21 21 20 18

2.78 2.33 2.36 2.55 2.82 2.33 2.43 2.42 2.92 2.84 2.78 2.50

125.1 111.8 110.9 91.8 84.6 79.2 75.3 72.6 61.3 59.6 55.6 45.0

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TABLE 3 RANK ORDER OF FREQUENCY 3 IMPORTANCE PRODUCT WITHIN EACH DOMAIN BY SEX AND SEVERITY Sex F Normal daily routine (n 5 22) Having to push yourself to remain alert Decreased ability to concentrate Having to fight to stay awake Decreased ability to remember things A decrease in your motivation to do exercise and leisure-type activities Having to force yourself to go to work, school, etc. A tendency to give what energy you have to accomplish only work-related activities Difficulty getting home maintenance or chores done around the house A decrease in your ability to do exercise and leisure-type activities Social interactions (n 5 23) Being told that your snoring disturbs your spouse’s or partner’s sleep Being told that your snoring was bothersome or irritating to your spouse or partner Less interest in socializing Wanting to be left alone A decrease in sexual intimacy A tendency to look for excuses for being tired An increase in the number of conflicts/arguments Having to sleep in separate bedrooms Emotional state (n 5 17) Frustration Irritability A feeling of depression or being down Impatience A decreased ability to cope with everyday issues Self perceptions (n 5 9) Perception of an actual or potential health problem because of your weight Concerns about your physical appearance Symptoms Daytime, n 5 28 Decreased energy Excessive fatigue Difficulty in staying awake while reading Ordinary activities require an extra effort to perform or complete Falling asleep if not stimulated or active Nocturnal, n 5 10 Waking up often during the night Restless sleep Concern about the times you stop breathing at night Waking up at night feeling like you were choking

patients regardless of sex. A sex difference in reporting healthrelated quality of life has been previously reported, but we are not aware of investigations that have addressed the possible causes (12, 20). We did not perform a separate analysis for age since the vast majority of patients who present to our sleep laboratory are between 35 to 65 yr of age. Almost all of the

Sleep Apnea Severity M

Mild

Moderate

Severe

Snorers

1 2 9 6 5 3 7

3 2 1 4 5 7 6

2 1 3 4 5 6 8

1 2 3 6 4 5 8

5 3 4 2 6 9 1

6 3 1 10 2 9 5

4 8

8 9

7 9

7 10

8 7

7 4

4 3

1 2

1 2

1 3

1 2

2 1

1 2 8 5 9 16

3 6 5 11 7 4

3 7 6 8 5 4

2 6 11 12 15 14

5 3 8 4 9 18

7 10 8 12 5 3

2 3 1 5 4

3 2 1 4 6

1 4 2 6 3

3 1 2 4 8

2 1 3 6 7

1 3 4 6 12

2 3

1 5

2 1

1 5

1 3

1 9

1 2 4 3 5

1 2 3 5 6

1 2 3 4 6

1 2 3 5 4

2 4 1 10 3

1 5 3 6 7

1 2 4 3

1 2 3 4

1 2 4 5

1 2 3 4

2 1 3 5

1 2 7 8

items in the SAQLI are applicable to people across this age range. Not unexpectedly, there were significant differences in the frequency 3 importance product between snorers and between patients with differing levels of sleep apnea severity. However, as with sex differences, the ranking of items was very similar across the different levels of sleep apnea severity

TABLE 4 MEAN FREQUENCY 3 IMPORTANCE PRODUCT OF DOMAINS BY SEX AND SEVERITY Sex

All items, n 5 109 Normal daily routine, n 5 22 Social interactions, n 5 23 Emotional state , n 5 17 Self perception, n 5 9 Symptoms Daytime, n 5 28 Nocturnal, n 5 10 Treatment-related symptoms

Sleep Apnea Severity

F (n 5 30)

M (n 5 83)

p Value

Mild (n 5 54)

Moderate (n 5 35)

Severe (n 5 24)

p Value

Snorers (n 5 50)

164.6 174.0 138.3 199.2 182.5

127.4 128.4 119.9 135.8 116.5

, 0.0001 0.0467 0.2339 0.0006 0.0222

120.2 143.4 111.1 137.1 102.4

134.7 160.3 123.6 154.3 132.5

173.7 207.2 153.6 177.9 194.4

, 0.0001 0.0017 0.0074 0.0249 0.0039

61.3 54.6 72.8 56.1 60.9

151.5 166.7 40.9

126.4 140.7 62.0

0.2007 0.3409 0.0193

114.5 140.9 43.6

128.7 140.9 64.9

179.8 166.1 73.8

0.0016 0.6239 0.0055

53.3 89.7

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Flemons and Reimer: Sleep Apnea Quality of Life Index TABLE 5 SAQLI AND SF-36 RESULTS IN 24 PATIENTS WITH SLEEP APNEA Domain

Mean

SD

SAQLI A SAQLI B SAQLI C SAQLI D SAQLI Total

4.7 5.3 4.9 3.5 4.6

1.3 1.3 1.3 1.6 1.1

Median 4.6 5.6 5.3 3.2 4.8

25% Quartile 3.9 4.0 4.1 2.3 3.7

75% Quartile 5.7 6.5 5.5 4.6 5.2

SF-36 PF SF-36 RP SF-36 BP SF-36 GH SF-36 VT SF-36 SF SF-36 RE SF-36 MH SF-36 Total

72.9 44.2 65.1 58.7 44.0 73.5 68.0 72.8 62.3

19.9 42.6 23.1 26.2 24.0 28.9 44.5 17.8 21.5

80.0 50.0 72.0 62.0 40.0 75.0 100.0 80.0 67.3

55.0 0.0 43.8 43.3 21.3 50.0 8.3 60.0 47.8

85.0 93.8 81.5 83.0 60.0 100.0 100.0 84.0 81.0

Range 1.9 to 6.9 2.8 to 7.0 1.8 to 6.8 1.0 to 7.0 2.1 to 6.8 40 to 100 0 to 100 20 to 100 0 to 97 0 to 85 0 to 100 0 to 100 28 to 100 11.3 to 91.5

Definition of abbreviations: SAQLI 5 Sleep Apnea Quality of Life Index; SF-36 5 36-Item Short-Form Health Survey; PF 5 physical functioning; RP 5 role-physical; BP 5 bodily pain; GH 5 general health; VT 5 vitality; SF 5 social functioning; RE 5 role-emotional; MH 5 mental health.

and snorers. Thus, we believe the SAQLI is an appropriate outcome measure for patients with sleep apnea and snorers. We did not test the snorers to exclude the possibility that some of them may also have had sleep apnea. However, they were selected at random from the office of an otolaryngologist for the treatment of snoring. We believe these patients are representative of the types of patients whose major problem is only snoring and this is reflected by their substantially lower frequency 3 importance product scores than even the patients with mild sleep apnea. If we had studied these patients and excluded those with evidence of sleep apnea it is likely their frequency 3 importance product scores would have been even lower. Although the SAQLI was developed to be an evaluative instrument capable of measuring subtle, but important, changes in quality of life after a therapeutic intervention, the distinct differences in the frequency 3 importance product scores between snorers, and patients with mild, moderate, or severe sleep apnea suggests that these items may well have discriminative capabilities as well. Content validity, as reflected by the comprehensiveness and range of items included, was established through the five approaches used to generate items, including the extensive involvement of patients with sleep apnea. Face validity was checked by clinicians and clinical researchers from across North America as well as by patients. Construct validity of the SAQLI as a measure of disease-specific quality of life was supported by the differences in the mean frequency 3 importance product that increased predictably from lowest in snorers to highest in patients with severe sleep apnea (Table 4). Construct validity was investigated further by asking 24 patients who had undergone a 4-wk trial of CPAP whether each item in the SAQLI had changed (yes or no) and if yes how much improvement or worsening there had been. There was a moderate correlation between this rating of change of the SAQLI items and the change in five of the eight SF-36 domains. The rating of change in SAQLI items showed that they did improve in the majority of patients after a trial of CPAP (Table 6). The change in each of the SAQLI domains and in total SAQLI scores post-CPAP was not evaluated in the initial testing of the questionnaire. The determination of its responsiveness in different study settings will be an important addition to the ongoing evaluation of the SAQLI’s validity as an outcome measure in sleep apnea clinical trials. CPAP is a highly successful physiologic treatment for sleep

apnea, but it has many potential side effects and drawbacks, which may in part explain the modest level of compliance documented in patients. We evaluated the characteristics of the SAQLI in patients after a 4-wk trial of CPAP, their use of which was documented by covert compliance meters. We have attributed improvements in the SAQLI and the SF-36 to the physiologic effects of CPAP; however, because we did not have a control group, we cannot entirely exclude a partial placebo response. We consider placebo responses to CPAP to be unlikely because of the obtrusive and at times uncomfortable nature of the treatment. In addition a satisfactory CPAP placebo has not been devised in which to compare the clinical response to treatment. If a successful CPAP placebo is devised it will be another important method of testing the SAQLI for construct validity. The initial testing of the questionnaire indicates that this population of patients with sleep apnea had a relatively normal distribution of responses without floor or ceiling effects (Table 5). The SAQLI showed a high degree of internal consistency as reflected by intraclass correlation coefficients (Cronbach’s alpha) of 0.88 to 0.92.

Figure 1. Comparison of SAQLI and SF-36 Total (r 5 0.21; p 5 0.3) and Vitality Domain (r 5 0.45; p 5 0.03) scores in 24 patients with sleep apnea prior to treatment with continuous positive airway pressure.

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TABLE 6 RATING OF CHANGE IN THE SAQLI AND CHANGE IN SF-36 RESULTS AFTER CPAP Domain

Mean

SD

Median

25% Quartile

75% Quartile

Range

R of C SAQLI A R of C SAQLI B R of C SAQLI C R of C SAQLI D R of C SAQLI total (A to D) R of C SAQLI total (A to E) Change SF-36 PF Change SF-36 RP Change SF-36 BP Change SF-36 GH Change SF-36 VT Change SF-36 SF Change SF-36 RE Change SF-36 MH Change SF-36 Total

2.3 1.6 1.6 4.0 2.4 2.0 2.3 23.3 4.7 9.5 17.0 5.1 17.8 9.1 11.1

2.2 1.8 1.8 1.8 1.7 1.8 18.1 37.2 20.8 20.8 27.3 25.8 39.6 19.5 21.0

2.0 0.7 1.1 4.2 1.6 1.4 0.0 0.0 2.0 5.0 15.0 0.0 0.0 8.0 4.8

0.3 0.0 0.0 2.2 1.1 0.6 0.0 0.0 212.0 0.0 0.0 0.0 0.0 0.0 22.6

4.5 2.7 2.6 5.6 4.2 3.6 5.0 50.0 16.0 15.0 25.0 0.0 33.0 12.0 19.6

0 to 6.4 0 to 6.2 0 to 6.3 1.6 to 6.2 0.5 to 6.1 20.2 to 6.1 225 to 60 225 to 100 223 to 62 215 to 77 235 to 85 237 to 88 233 to 100 220 to 68 24.6 to 80

Definition of abbreviations: CPAP 5 continuous positive airway pressure; R of C 5 rating of change. For other definitions, see Table 5.

During the item identification phase we assumed that patients would identify problems they had performing activities like their usual job, or with leisure activities. We had not anticipated that for many patients the problems they actually have is not whether they could do an activity or perform their job, but rather it was how much they had to push themselves to accomplish them and the lack of energy they had left over for other activities. The wording in the SAQLI reflects this in that most questions ask either how much difficulty patients have with something or how often they can do it rather than whether they can do it. It is possible that this characteristic of the SAQLI is population-specific, that is, it may be more or less important for people in different countries and in different cultures. It is also possible that responses to treatment will vary across cultures. Thus, it will be important for the SAQLI to be validated in different ethnic groups and trials of different modes of treatment. We constructed the SAQLI to be administered by a trained interviewer using color-coded response cards with a sevenlevel Likert scale, similar in design to other quality of life questionnaires (12, 15). We found that patients reported a large number of symptoms caused by sleep apnea or snoring and by treatment of these disorders. We therefore elected to have patients select the five most important symptoms that affect them from a list of commonly reported symptoms. Provision was also made for patients to add other symptoms that are not on the list. This procedure has been used successfully in other disease-specific quality of life questionnaires (12, 13). Initially, we elected to include a patient-based weighting factor for each domain that reflected how important the patients felt the domain was to their overall quality of life. However, we found it made a negligible difference in scores and added a level of complexity that some patients found confusing. Therefore, we elected not to weight the importance of individual questions or individual domains in the SAQLI, again in keeping with the construction of other disease-specific quality of life scales (12–15). The exception to this is Domain E (Treatment-related Symptoms). It was clear from the item selection phase that these symptoms had a much lower frequency 3 importance product than did the other domains (Table 2). Because we incorporated this domain to reflect the potential for adverse consequences on quality of life from treatment, it is subtracted from the total of Domains A to D prior to the total SAQLI score being calculated. This strategy

has the effect of reducing the apparent benefit of treatment to reflect what we believe to be the “net” benefit. This is a new concept in the design of a quality of life instrument that we felt was important because all of the available treatments for sleep apnea and snoring are known to have substantial adverse effects in many patients. Because patients reported that on average this negative impact of treatment was less than the positive impact, we felt it was important for each patient to rate the relative positive and negative aspects of treatment and use this as a “weighting factor” for treatment-related symptoms. We believe that by including Domain E (Treatment-related Symptoms) and weighting it according to its relative impact on quality of life, the SAQLI more adequately reflects the net effect of treatment. As shown in Table 6 the average weighted reduction in the SAQLI score by Domain E is 0.4. Although further testing of validity, reliability, and responsiveness are required we believe the methodology we used, plus the data on 24 patients with sleep apnea, indicates that this questionnaire, the only disease-specific sleep apnea quality of life instrument that has been developed, can be used in clinical trials. Our methodology was almost identical to other

Figure 2. SAQLI Rating of Change Score compared with the change in the SF-36 Total (r 5 0.60; p 5 0.018) and Vitality Domain (r 5 0.81; p 5 0.0002) scores in 15 patients with sleep apnea after successful completion of a trial of continuous positive airway pressure.

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T. K. Hiller. 1992. Evaluation of impairment of health related quality of life in asthma: development of a questionnaire for use in clinical trials. J. Clin. Epidemiol. 47:76–83. 20. Kaplan, R. M., J. P. Anderson, and D. L. Wingard. 1991. Gender differences in health-related quality of life. Health Psychol. 10:86–93.

instruments that have been published and validated for disorders such as asthma and chronic obstructive lung disease, heart failure, and rhinoconjunctivitis (12–15). In each of these other disease states these indices have proved to be valid, responsive, and reliable and thus important outcome measures in clinical trials. The true utility of the Calgary SAQLI will only be established by its use in different types of clinical trials and by several different investigators. We hope that other investigators will include it as an outcome measure in future clinical trials, especially those assessing a patient’s response to treatment for sleep apnea.

APPENDIX

Acknowledgment : The writers are grateful to Dr. Gordon Guyatt for several helpful suggestions regarding questionnaire format and to Lori Ontonio, Sharon Tanguay, Jeanne Kim, Norma Thurston, and Alamelu Iyer for their efforts in conducting patient interviews and data entry.

A. Daily Functioning

References 1. Strohl, K. P., and S. Redline. 1996. Recognition of obstructive sleep apnea. Am. J. Respir. Crit. Care Med. 154:279–289. 2. Ringler, J., R. C. Basner, R. Shannon, R. Schwartzstein, H. Manning, S. E. Weinberger, and J. W. Weiss. 1990. Hypoxemia alone does not explain blood pressure elevations after obstructive apneas. J. Appl. Physiol. 69:2143–2148. 3. Cheshire, K., H. Engleman, I. Deary, C. Shapiro, and N. J. Douglas. 1992. Factors impairing daytime performance in patients with sleep apnea/hypopnea syndrome. Arch. Intern. Med. 152:538–541. 4. Hudgel, D. W. 1989. Neuropsychiatric manifestations of obstructive sleep apnea: a review. Int. J. Psychiatry Med. 19:11–22. 5. Engleman, H. M., S. E. Martin, I. J. Deary, and N. J. Douglas. 1994. Effect of continuous positive airway pressure treatment on daytime function in sleep apnoea/hypopnoea syndrome. Lancet 343:572–575. 6. Johns, M. W. 1991. A new method of measuring daytime sleepiness: the Epworth Sleepiness Scale. Sleep 14:540–545. 7. Hunt, S. M., J. McEwan, and S. P. McKenna. 1985. Measuring health status: a new tool for clinicians and epidemiologists. J. R. Coll. Gen. Pract. 35:185–188. 8. Ware, J. E., and C. D. Sherbourne. 1992. The MOS 36-item Short-Form Health Survey (SF-36): I. Conceptual framework and item selection. Med. Care 30:473–483. 9. Gall, R., L. Isaac, and M. Kryger. 1993. Quality of life in mild obstructive sleep apnea. Sleep 16:S59–S61. 10. Jenkinson, C., J. Stradling, and S. Petersen. 1997. Comparison of three measures of quality of life outcome in the evaluation of continuous positive airway pressure therapy for sleep apnoea. J. Sleep Res. 6:199– 204. 11. Guyatt, G. H., C. Bombardier, and P. X. Tugwell. 1986. Measuring disease-specific quality of life in clinical trials. C.M.A.J. 134:889–895. 12. Juniper, E. F., G. H. Guyatt, R. S. Epstein, P. J. Ferrie, R. Jaeschke, and T. K. Hiller. 1992. Evaluation of impairment of health related quality of life in asthma: development of a questionnaire for use in clinical trials. Thorax 47:76–83. 13. Guyatt, G. H., L. B. Berman, M. Townsend, S. O. Pugsley, and L. W. Chambers. 1987. A measure of quality of life for clinical trials in chronic lung disease. J. Clin. Epidemiol. 42:773–778. 14. Guyatt, G. H., S. Norgradi, S. Halcrow, J. Singer, M. J. J. Sullivan, and E. L. Fallen. 1989. Development and testing of a new measure of health status for clinical trials in heart failure. J. Gen. Intern. Med. 4:101–107. 15. Juniper, E. F., and G. H. Guyatt. 1991. Development and testing of a new measure of health status for clinical trials in rhinoconjunctivitis. Clin. Exp. Allergy 21:77–83. 16. Engleman, H. M., S. E. Martin, and N. J. Douglas. 1994. Compliance with CPAP therapy in patients with the sleep apnoea/hypopnoea syndrome. Thorax 49:263–266. 17. Kribbs, N. B., A. I. Pack, L. R. Kline, P. L. Smith, A. R. Schwartz, N. M. Schubert, S. Redline, J. N. Henry, J. E. Getsy, and D. F. Dinges. 1993. Objective measurement of patterns of nasal CPAP use by patients with obstructive sleep apnea. Am. Rev. Respir. Dis. 147:887–895. 18. Jaeschke, R., J. Singer, and G. H. Guyatt. 1989. Measurement of health status: ascertaining the minimal clinically important difference. Control. Clin. Trials 10:407–415. 19. Juniper, E. F., G. H. Guyatt, R. S. Epstein, P. J. Ferrie, R. Jaeschke, and

Calgary Sleep Apnea Quality of Life Index (Interviewer) This questionnaire has been designed to find out how you have been doing and feeling over the last 4 wk. You will be questioned about the impact that sleep apnea and/or snoring may have had on your daily activities, your emotional functioning, and your social interactions, and about any symptoms they might have caused.

I. Most important daily activity. With regard to performing your most important, usual daily activity (e.g., work, school, child care, housework, etc.) during the previous 4 wk: 1. How much have you had to force yourself to do this activity? [yellow card] 2. How much of the time have you had to push yourself to remain alert while performing this activity? [yellow card] 3. How often have you adjusted your schedule to avoid this activity because you felt that you would be unable to remain alert while doing it? [yellow card] 4. How often do you use all of your energy to accomplish only this activity? [yellow card] II. Secondary activities. With regard to activities other than your most important daily activity during the previous 4 wk: 5. How much difficulty have you had finding the energy to exercise and/or do activities that you find relaxing (leisure activities)? [green card] 6. How much difficulty have you had finding the time for activities that you find relaxing? [green card] 7. How much difficulty have you had with your ability to do exercise and/or activities that you find relaxing? [green card] 8. How much difficulty have you had getting chores done around the place where you live? [green card] III. General functioning. During the previous 4 wk: 9. How much difficulty have you had with trying to remember things? [green card] 10. How much difficulty have you had with trying to concentrate? [green card] 11. How much of a problem have you had with having to fight to stay awake? [red card]

B. Social Interactions The following questions pertain to how your relationship with your partner, other household members, relatives, and/or close friends have been during the previous 4 wk. If you have not interacted with a partner, etc. in the previous 4 wk, please try to work out how your relationship might have been with these people. 1. How upset have you been about being told that your snoring was bothersome or irritating? [green card] 2. How upset have you been about having to (or possibly having to) sleep in separate bedrooms from your partner? [green card] 3. How upset have you been as a result of frequent conflicts or arguments? [green card] 4. How aware have you been of not wanting to talk to other people? [green card] 5. How much concern have you had about the need to make special sleeping arrangements if you were traveling and/or staying with someone? [green card] 6. How guilty have you felt about your relationship with family members or close personal friends? [green card] 7. How often have you looked for excuses for being tired? [yellow card] 8. How often have you experienced wanting to be left alone? 9. How often have you felt like not wanting to do things together with your partner, children, and/or friends? [yellow card]

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10. How much of a problem have you felt there is with your relationship to the person who is closest to you? [red card] 11. How much of a problem have you had from not being involved in family activities? [red card] 12. How much of a problem have you had with inadequate and/or infrequent sexual intimacy? [red card] 13. How much of a problem have you had with a lack of interest in being around other people? [red card]

C. Emotional Functioning With respect to how you have been feeling inside during the previous 4 wk: 1. How often have you been feeling depressed, down, and/or hopeless? [yellow card] 2. How often have you been feeling anxious or fearful about what was wrong? [yellow card] 3. How often have you been feeling frustrated? [yellow card] 4. How often have you been feeling irritable and/or moody? [yellow card] 5. How often have you been feeling impatient? [yellow card] 6. How often have you been feeling that you are being unreasonable? [yellow card] 7. How often have you been getting easily upset? [yellow card] 8. How often have you experienced a tendency to become angry? [yellow card] 9. How often have you been feeling like you were unable to cope with everyday issues? [yellow card] 10. How concerned have you been about your weight? [green card] 11. How concerned have you been about heart problems (heart attacks or heart failure) and/or premature death? [green card]

D. Symptoms Below is a list of symptoms that some people with sleep apnea and/or who snore may experience. As each symptom is read please indicate whether it has been a problem or not (answer yes or no). Circle those symptoms that you have experienced during the previous 4 wk. Once the list is finished please write down additional symptoms in the blank spaces you may have had that are not included in the list below. Next select the five most important symptoms you have experienced. For each of the five symptoms please identify how much of a problem it has been. [red card] 1. Decreased energy 2. Excessive fatigue 3. Feeling that ordinary activities require an extra effort to perform or complete 4. Falling asleep at inappropriate times or places 5. Falling asleep if not stimulated or active 6. Difficulty with a dry or sore mouth/throat upon awakening 7. Waking up often (more than twice) during the night 8. Difficulty returning to sleep if you wake up in the night 9. Concern about the times you stop breathing at night 10. Waking up at night feeling like you were choking 11. Waking up in the morning with a headache 12. Waking up in the morning feeling unrefreshed and/or tired 13. Waking up more than once per night to urinate 14. A feeling that your sleep is restless 15. Difficulty staying awake while reading 16. Difficulty staying awake while trying to carry on a conversation 17. Difficulty staying awake while trying to watch something (concert, movie, TV) 18. Fighting the urge to fall asleep while driving 19. A reluctance or inability to drive for . 1 h 20. Concern regarding close calls while driving due to your inability to remain alert 21. Concern regarding your or other’s safety when you’re operating a motor vehicle or machinery 22. ______________________________________________________ 23. ______________________________________________________

E. Treatment-related Symptoms If you haven’t had some type of therapy for sleep apnea and/or snoring leave this section blank. Below is a list of symptoms that some

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people who have been treated for sleep apnea and/or snoring may experience. As each symptom is read please indicate whether it has been a problem or not (answer yes or no). Circle those symptoms that you have experienced during the previous 4 wk. Once the list is finished please write down any symptoms in the blank spaces you may have had that are not included in the list below. Next select the five most important symptoms you have experienced. For each of the five symptoms please identify how much of a problem it has been. [red card] 1. Runny nose 2. Stuffed or congested or blocked nose 3. Excessive dryness of the nose or throat passages, especially upon awakening 4. Soreness in the nose or throat passages 5. Headaches 6. Eye irritation 7. Ear pain 8. Waking up frequently during the night 9. Difficulty returning to sleep if you awaken 10. Air leakage from the nasal mask 11. Discomfort from the nasal mask 12. Marks or rash on your face 13. Complaints from your partner about the noise of the CPAP machine 14. Having fluid/food pass into your nose when you swallow 15. A change in how your voice sounds 16. Pain in the throat when swallowing 17. Pain or aching in your jaw joint or jaw muscles 18. Feeling self conscious 19. Aching in your teeth that lasts at least an hour 20. Discomfort, aching, or tenderness of your gums 21. Hardship in being able to pay for the treatment 22. A sense of suffocation 23. Excessive salivation 24. Difficulty chewing in the morning 25. Difficulty chewing with your back teeth that persists most of the day 26. Movement of the teeth so that the upper and lower teeth no longer meet properly 27. ______________________________________________________ 28. ______________________________________________________

F. Impact Complete this section only if you have completed section E above. I. Please think of the questions in Sections A, B, C, and D. Having been treated for your sleep apnea and/or snoring do you believe that overall there has been an improvement in your quality of life since you started treatment? If yes, how much of an impact on your quality of life has there been as reflected by the questions asked in Sections A, B, C, and D. Place a mark on the line. Scale: 0—————————————————————————10 (no impact) (extremely large impact) II. Please think of the symptoms that developed as a result of being treated for sleep apnea and/or snoring that you highlighted in Section E. How much of an impact on your quality of life have these symptoms had? Scale: 0—————————————————————————10 (no impact) (extremely large impact)

Response Options Yellow card 1. All the time 2. A large amount of the time 3. A moderate to large amount of the time 4. A moderate amount of the time 5. A small to moderate amount of the time 6. A small amount of the time 7. Not at all

Flemons and Reimer: Sleep Apnea Quality of Life Index Green card 1. A very large amount 2. A large amount 3. A moderate to large amount 4. A moderate amount 5. A small to moderate amount 6. A small amount 7. None Red card 1. A very large problem 2. A large problem 3. A moderate to large problem 4. A moderate problem 5. A small to moderate problem 6. A small problem 7. No problem A note about scoring. To obtain mean scores for Domains A through D the total score of each domain should be divided by the total number of questions answered. When the SAQLI is administered after a therapeutic intervention, allowance has been made for the possiblity that the treatment, even if it is “successful,” may have some in-

503 dependent negative consequences on a patient’s quality of life. The scores from Domain E (Treatment-related Symptoms), are dealt with in a manner different from that of the other four domains. First the scores require recoding (7 to 0, 6 to 1, 5 to 2, 4 to 3, 3 to 4, 2 to 5, and 1 to 6). For Domain E the mean recoded score is obtained by dividing the total score by 5 (regardless of how many symptoms were identified). Next, the mean value of the recoded scores needs to be weighted according to the impact of the treatment-related symptoms on quality of life in comparison with the impact of the improvement of Domains A through D. Weighting is accomplished by dividing the impact score for Domain E (a number from 0 to 10) by the impact score for Domains A through D (Section F of the SAQLI). If this quotient exceeds 1, the result should be reduced so that the weighting factor never exceeds 1. The mean recoded score from Domain E is multiplied by the weighting factor, and it is this product that should be subtracted from the sum of the mean scores from Domains A, B, C, and D. To obtain the final SAQLI score the sum of the mean domain scores A, B, C, and D is divided by 4. If Domain E has been used after a therapeutic intervention, the SAQLI score is obtained by summing the mean domain scores A, B, C, and D, subtracting the mean recoded Domain E score (that has been adjusted by the weighting factor described above) and dividing by 4.