OUTCOMES IN PRACTICE

Pediatric Health-Related Quality of Life Measurement Technology: A Guide for Health Care Decision Makers James W. Varni, PhD, Michael Seid, PhD, and Paul S. Kurtin, MD

M

anaged care organizations, health care providers, and purchasers of health care services are concerned not only with improving health and wellbeing but also with documenting the value of health care services provided. Outcomes assessment is essential to achieving these goals. Health outcomes assessment refers to the evaluation of health care products, services, or programs and the consequences of their use [1]. Outcomes assessment provides critical information regarding the effectiveness and quality of health care and is an essential component of performance improvement projects. Comprehensive outcomes evaluation encompasses clinical, economic, and patient-based outcomes. Patient-based outcomes are outcomes best described by the patient, such as satisfaction with care and perceptions of quality of life. Although quality of life can be construed to encompass all aspects of an individual’s life (eg, housing, neighborbood, work, school), health-related quality of life (HRQOL) generally refers to those domains of health that can potentially be influenced by the health care system. Health-related quality of life, health status, and functional status are terms often used interchangably to describe patients’ perceptions of their health, but HRQOL is considered the more comprehensive term [2]. The importance of assessing the patient’s perception of his or her HRQOL has been well established [3], and a number of standard adult measures have been developed in recent years. In contrast, standard measures validated for use in evaluating the health care received by pediatric patients are few in number and in the early stages of development. In order to generate an evidence-based pediatric health care database for use in determining the appropriateness of health care services on a local and national basis, pediatric HRQOL instruments with excellent measurement precision are required. This paper will discuss conceptual and methodological issues related to pediatric HRQOL measurement, evaluate several existing instruments, and offer some guidance on instrument selection. Vol. 6, No. 4

Defining Health-Related Quality of Life Most HRQOL measures have evolved from the World Health Organization’s definition of health: a state of complete physical, mental, and social well-being, not merely the absence of disease or infirmity [4]. For patients with chronic health conditions, the goal of health care is to restore them to the fullest health possible by improving symptom management, treatment adherence, and their ability to cope with the impact of the condition. For this reason, HRQOL may be more important than biomedical measures when assessing patients with chronic health conditions [5]. The value of HRQOL measurement in patients with chronic health conditions has repeatedly been demonstrated with adults [6,7]. It follows that if we want to ensure that children receive the best possible health care in the most appropriate settings from the most qualified professionals, we need to assess their health status. Self-Report versus Proxy-Report It is considered self-evident that patient self-report of HRQOL is the “gold standard” for measurement in adults. In pediatrics, several issues, including cognitive-developmental considerations, complicate the decision regarding the best respondent for HRQOL assessment. While some measures allow for pediatric patient self-report, others rely on a proxy, such as a parent, to rate the child’s HRQOL; however, selfreport and proxy-report often do not agree. This imperfect concordance has been consistently noted in research comparing adult patients’ self-reports and the reports of their health care providers and significant others (eg, spouses) [3]. In pediatrics, a lack of congruence has been documented among

James W. Varni, PhD, Senior Scientist, Center for Child Health Outcomes, Children’s Hospital and Health Center, San Diego, CA, Professor of Psychiatry, University of California, San Diego, School of Medicine, San Diego, CA, e-mail: [email protected]; Michael Seid, PhD, Research Scientist, Center for Child Health Outcomes, Children’s Hospital and Health Center, San Diego; and Paul S. Kurtin, MD, Director, Center for Child Heath Outcomes, Children’s Hospital and Health Center, San Diego.

JCOM April 1999 33

PEDIATRIC QUALITY OF LIFE the reports of physically healthy children and the reports of their parents, teachers, and health care professionals in assessments of the childrens’ functional status [8]. Agreement among observers has been found to be lower for subjective experiences (eg, pain, nausea, depression, anxiety) than for observable events (eg, emesis, walking, activities of daily living, behavior problems). This lack of agreement among reporters of pediatric patient functioning has been termed “cross-informant variance” [9] and has been observed in HRQOL assessment across multiple pediatric health conditions [10–13]. Cross-informant variance is hardly surprising given that HRQOL derives from perceptions of the impact of disease and treatment [14], and it clearly underscores the need for pediatric patient self-report instruments with definitive measurement precision across the developmental stages of childhood and adolescence [12]. Although reliable and valid self-report instruments are essential for the accurate determination of pediatric HRQOL, parent proxy-report is important for several reasons. Because children are rarely in a position to refer themselves for treatment, even when they are experiencing symptoms and health-related problems, parents’ perceptions of a child’s HRQOL influences the likelihood that health care will be sought for the child. Further, the use of parent proxy-report to estimate pediatric patient HRQOL may be necessary when the patient is unable or unwilling to complete the HRQOL measure because of young age or illness variables. Generic versus Disease-Specific Measurement Two measurement strategies typically are used in health status assessment: (1) generic population/epidemiologic assessment and (2) disease- or condition-specific assessment [15]. In generic assessment, the goal is breadth, or the ability to measure general health status across diverse samples including screening healthy populations for specific problems related to their health and well-being. Generic measures are designed to be broadly applicable and can be used to make comparisons across diverse patient populations. In disease-specific assessment, the goal is to assess health status within a circumscribed clinical sample, such as patients with asthma [16,17], cystic fibrosis [18], cancer [19–22], chronic headache [23], skin problems [24], spina bifida [25], or specific congenital or acquired chronic physical impairments such as limb deficiencies [26–28]. Disease-specific measures have the advantage of being more sensitive to clinical change in designated patient groups, a quality that is often not found in generic measures [29]. However, these specific measures are limited in their usefulness in making comparisons across diverse patient populations, including benchmarking with healthy population norms. Thus, a trade-off between clinical usefulness and comparative data often exists in selecting one type of measure over another. A third type of measurement, utility assessment, is 34 JCOM April 1999

based on health preferences among the general population. The feasibility and usefulness of this approach with pediatric samples is doubted given the cognitive-developmental sophistication required [30] and will not be discussed here. An alternative measurement model to the generic versus disease-specific dichotomy is an assessment strategy that combines both approaches. In this modular measurement strategy, a generic core measure designed for use in pediatric patients with acute and chronic health conditions as well as in healthy populations is paired with supplemental conditionspecific modules designed for use with designated patient samples. This strategy enables decision makers to measure disease- and treatment-related symptoms or health problems of discrete patient subgroups as well as compare diverse groups of patients. The supplemental modules assess specific disease or treatment effects and other relevant HRQOL issues not sufficiently covered in the core measure, whereas the core measure affords the opportunity to make comparisons across disease groups and with healthy population norms. The availability of physically healthy child and adolescent norms provides an essential benchmarking role not only in interpreting the meaning of scale scores but also as a metric with which to evaluate the outcome of interventions for pediatric patients with chronic health conditions. Initial research on the utility of this measurement strategy is very promising [12,13]. Attributes of HRQOL Instruments Three basic dimensions can be used to evaluate a potential HRQOL instrument: conceptualization, measurement properties (psychometrics), and practicality. Conceptualization refers to the theoretical underpinnings of the measurement: How do the test constructors think of HRQOL? Is there a theoretical or empirical basis for this conceptualization? Is this conceptualization consistent with the potential user’s ideas of how HRQOL should be measured in a particular case? Is pediatric HRQOL to be measured by child selfreport, proxy-report, or both? If there is a proxy-report form, is it parallel to the child self-report? Similar to laboratory tests for biological disease, standardized tests for HRQOL assessment must have excellent measurement properties (reliability and validity) [10]. Reliability refers to how well a measure reflects true scores (as opposed to error) [31]. In practice, reliability is often determined via internal consistency, or how well each test item correlates with the scale of which it is intended to be part. A general rule is that internal consistency should be at least 0.70 for group comparisons and at least 0.90 for individual comparisons [31]. Validity refers to how well an instrument measures what it purports to measure. Validity is not an allor-nothing quality. Most tests have some degree of validity, and virtually no HRQOL test has perfect validity in all situations. Vol. 6, No. 4

OUTCOMES IN PRACTICE Table. Comparison of Pediatric HRQOL Instruments Instrument Attribute

PedsQL

CHQ*

CHIP

FSII(R)

Conceptualization Multidimensional

Yes

Yes

Yes

Yes

Scales assessing physical health

Yes

Yes

Yes

Yes

Scales assessing mental health

Yes

Yes

Yes

No

Perception of minimal problems, high well-being

Minimal problems, health does not interfere with role, high well-being

Able to participate fully in appropriate tasks

Few behavioral manifestations of problems

Yes

No

No

No

Yes

Yes, for parent form Mixed‡

Yes

Yes

Group

Group

Group/individual

Validity – factor structure

Yes

Yes

Yes

Yes

Validity – known groups

Yes

No

Yes

Yes

Validity – hospital days, days lost

Yes

No

Yes

Yes

Self, interviewer

Self, interviewer

Self, interviewer

Interviewer

30 items

87 items

175 items

43 items, 14-item short form

Less than 5 minutes

No data

45 minutes

No data

Meaning of high scores

Modular format Reliability and validity Peer-reviewed psychometric data Internal consistency†

Practicality (ease of use) Mode of administration Length Time to complete Scored easily

Yes

No

Yes

Yes

Patient-report age range (yrs)

5 to 18

10 to 17

11 to 17

No self report

Proxy-report age range (yrs)

2 to 18

10 to 17

No proxy report

0 to 16

Yes

No

No

No

English, Spanish

English, Spanish, others

English

English, Spanish

Parallel patient- and proxy-reports Languages

PedsQL = Pediatric Quality of Life Inventory; CHQ = Child Health Questionnaire; CHIP = Child Health and Illness Profile; FSII(R) = Functional Status Measure (updated). *Pediatric self-report format, unless otherwise indicated. †Internal consistency reliability should exceed 0.70 for group comparisons, 0.90 for individual comparisons. ‡Some scales fall above 0.70, although others do not.

Practicality refers to the test’s usefulness in real-world settings as well as the ease with which it is administered, scored, and interpreted.

(or both) and how these reports are related (Table). In cases in which both a self-report and proxy-report exist, the discussion focuses on the properties of the self-report form.

Properties of Select Instruments Although there are numerous disease- and condition-specific pediatric HRQOL instruments, this discussion will consider only instruments that can be used in more than one population. The instruments discussed vary along many dimensions, including whether the measure is self-report or proxy-report

The PedsQL™ (Pediatric Quality of Life Inventory™) During the past 15 years, Varni and associates have conducted a programmatic research effort in measurement instrument development, which has resulted in the items contained in the PedsQL (Figure). The PedsQL has been designed as a modular HRQOL measurement instrument for pediatric

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PEDIATRIC QUALITY OF LIFE health conditions, with generic core scales and conditionspecific disease and treatment related modules [12,13]. It consists of parallel child self-report and parent proxy-report of the child’s HRQOL such that the parent-report items are thirdperson verbatim copies of the items found on the child’s report. Child and parent reports of the child’s HRQOL can be compared across the age range. Conceptualization. The PedsQL conceptualizes pediatric HRQOL as the patient’s perceptions of the impact of disease and treatment in a variety of health and well-being domains [2,32], including physical, emotional, social, and school functioning and general perceptions of well-being [4,33,34]. This conceptualization is consistent with recent writings [35] suggesting that it is reasonable to expect that “someone in the best possible physical and emotional state compatible with their medical condition has the best chance of achieving a high quality of life, whatever this may mean to the individual concerned.” The PedsQL multidimensional generic core scales encompass the essential domains for pediatric HRQOL assessment: physical functioning (8 items), emotional functioning (5 items), social functioning (5 items), school functioning (5 items), well-being (6 items), and a global perception of overall health status (1 item). Scales are scored from 0 to 100, with 100 indicating highest HRQOL. Reliability and validity. The PedsQL generic core scales were designed to be used across various pediatric health conditions, with PedsQL cancer, asthma, and arthritis modules developed and field-tested thus far [12,13]. The PedsQL generic core scales and condition-specific modules have demonstrated good internal consistency reliability, with coefficient alpha generally ranging from 0.70 to 0.92 for patient self-report of health and well-being [12,13]. Construct validity has been demonstrated for both item-level and scale-level analyses [12,13]; clinical validity has been established by demonstrating that PedsQL scores distinguish between pediatric cancer patients on- and off-treatment [12] and that PedsQL scale scores are associated in the expected direction with disease- and treatment-related symptoms in patients with asthma and arthritis [13] and are strongly related to days missed from school for patients and days missed from work for parents [13]. PedsQL modules are currently being developed for pediatric diabetes, cystic fibrosis, sickle cell disease, cerebral palsy, cardiology, and medically fragile patients. The PedsQL is continuously being field-tested nationally in pediatrician offices, hospital specialty clinics, community settings, and schools, as well as in international field trials. It is anticipated that 5000 to 10,000 pediatric respondents and their parents will be accrued by 1999, including physically healthy school children and children with a wide diversity of chronic health conditions. 36 JCOM April 1999

Practicality. The PedsQL is a 30-item measure and takes less than 5 minutes to complete. Missing data rates are about 0.01% of item responses for the pediatric cancer, arthritis, and asthma samples [12,13]. Scoring is very straightforward, with all items scored on a 0 to 4 scale and easily converted to the 0 to 100 scale for standardized interpretation. The age range for the PedsQL is 5 to 18 years for patient self-report and 2 to 18 years for parent proxy-report. The instrument has been field-tested in English and Spanish, is currently being field-tested in German, and is being adapted internationally. The measure is self-administered for parents and older children, with children aged 5 to 7 years completing the measure with the aid of an interviewer. Child Health Questionnaire (CHQ) The CHQ parent and child questionnaires encompass several domains of physical health, mental health, and role functioning [36]. The parent-report and child-report forms are similar but not parallel. The CHQ user’s manual indicates that the questionnaires are generic health measures for use in general survey research [36]. Conceptualization. The CHQ conceptualizes HRQOL as consisting of physical and psychosocial well-being measured along the dimensions of status, disability, and personal evaluation [36]. Summary scales for the CHQ include physical functioning, self-esteem, mental health, general health perceptions, behavior, bodily pain, role/social–physical (the impact of physical functioning on role performance), role/ social–emotional/behavioral (the impact of emotional/ behavioral functioning on role performance), parental impact/time, parental impact/emotional, family activities, and family cohesion. Reliability and validity. Item-level analyses show a wide range in the performance of individual items and scale scores, with internal consistency alpha coefficients ranging from 0.62 to 0.97. Construct validity for the child self-report CHQ is documented via item-level analysis. The CHQ user’s manual documents the clinical validity of the parent-report form, but it does not address the child-report form. Norms are available for the parent-report form but not for the child-report form. Practicality. The parent-report form is available in 50- and 28-item versions, but the child-report form is 87 items long. The length of the child-report form may be a factor in data completeness. For example, in the middle-school sample, 53% to 60% of 10 to 12 year olds and 72% to 74% of older children completed all 87 items [36]. In the clinical groups, completion rates ranged from 63% to 77% [36]. Scoring is somewhat complicated by the fact that different items have different numbers of responses and that item values on some Vol. 6, No. 4

OUTCOMES IN PRACTICE Below is a list of things that might be a problem for you. Please tell us how much of a problem each one has been for you during the past ONE month. There are no right or wrong answers. If you do not understand a question, please ask for help. In the past ONE month, how much of a problem has this been for you . . . About My Health And Activities It is hard for me to walk more than one block It is hard for me to run It is hard for me to do sports activity or exercise It is hard for me to lift something heavy It is hard for me to take a bath or shower by myself It is hard for me to do chores around the house I hurt or ache I have low energy About My Feelings I feel afraid or scared I feel sad or blue I feel angry I have trouble sleeping I worry about what will happen to me How I Get Along With Others I have trouble getting along with other kids Other kids do not want to be my friends Other kids tease me I cannot do things that other kids my age can do It is hard to keep up when I play with other kids About School It is hard to pay attention in class I forget things I have trouble keeping up with my schoolwork I miss school because of not feeling well I miss school to go to the doctor or hospital

Never 0 0 0 0 0 0 0 0 Never 0 0 0 0 0 Never 0 0 0 0 0 Never 0 0 0 0 0

Almost Never 1 1 1 1 1 1 1 1 Almost Never 1 1 1 1 1 Almost Never 1 1 1 1 1 Almost Never 1 1 1 1 1

Sometimes

Often

Almost Always

2 2 2 2 2 2 2 2

3 3 3 3 3 3 3 3

4 4 4 4 4 4 4 4

Sometimes

Often

Almost Always

2 2 2 2 2

3 3 3 3 3

4 4 4 4 4

Sometimes

Often

Almost Always

2 2 2 2 2

3 3 3 3 3

4 4 4 4 4

Sometimes

Often

Almost Always

2 2 2 2 2

3 3 3 3 3

4 4 4 4 4

Sometimes

Often

Almost Always

2 2 2 2 2 2

3 3 3 3 3 3

4 4 4 4 4 4

Please tell us how much each sounds like you during the past ONE month. In the past ONE month, how much does this sound like you . . . About Me I feel happy I feel good about myself I feel good about my health I get support from my family and friends I think good things will happen to me I think my health will be good in the future

Never 0 0 0 0 0 0

Almost Never 1 1 1 1 1 1

In the past ONE month . . . In General In general, how is your health?

Bad

Fair

Good

Very Good

Excellent

0

1

2

3

4

Figure. Pediatric Quality of Life Inventory (PedsQL). Version shown is adapted from child report for ages 8 to 12 years. © 1998 by JW Varni. All rights reserved.

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PEDIATRIC QUALITY OF LIFE items have to be recoded based on weightings. The parent proxy-report form is available for children aged 5 to 18 years, and the child self-report form is available for patients aged 10 to 18 years. The instrument is available in English, Spanish, French, and other languages. Both parent and child reports can be self-administered or interviewer-administered. The Child Health and Illness Profile (CHIP) The CHIP [37] is a broad measure of health for use in epidemiologic surveys of general health with adolescents aged 11 to 17 years [38]. The measure consists of an adolescent self-report form. Work is underway on a child self-report form, but this has yet to be disseminated; there is no parent proxy-report form. Conceptualization. The CHIP is defined as “a comprehensive instrument that broadly defines health as the ability to participate fully in developmentally appropriate physical, psychological, and social tasks” [37]. The measure assesses 6 broad domains of health functioning: activity, comfort, satisfaction with health (perceived well-being), disorders, achievement, and resilience. Each domain has various subdomains. Reliability and validity. The CHIP has been tested in several thousand adolescents, including well, acutely ill, and chronically ill patients. Overall, the evidence shows that internal consistency reliability is sufficient for use in group comparisons [37,39]. Content validity has been addressed via focus groups and expert consultation [37]. Construct and clinical validity has been demonstrated in the ability of the instrument to distinguish among known groups of adolescents [37,39,40]. The CHIP also has been validated for describing adolescent reports of health needs [41,42]. Practicality. The CHIP is self-administered, but it is 175 items long and takes approximately 45 minutes to complete [37]. It has been used almost exclusively in research settings and epidemiologic studies. FSII(R) The Functional Status Measure has been updated as the FSII(R) [43]. It was developed to assess the health status of chronically ill children. This measure is available only as parent-report and is administered via interview. The long form is 43 items. A shorter, 14-item core measure has been developed but still requires a clinical interview format. A self-report format has been reported in the literature [44]. Conceptualization. The FSII(R) conceptualizes health status as the behavioral manifestation of functioning. The measure inventories behavioral manifestations of illness that interfere with an individual’s performance of the full range of age38 JCOM April 1999

appropriate activities. The developers viewed behavior as the final common pathway of health and defined the healthy child as one who exhibits age-appropriate physical, psychological, intellectual, and social behaviors [43]. This measure attempts to isolate health-related problems from other behaviors by asking, for each question, whether the behaviors are due to a health problem. Reliability and validity. The FSII(R) 43-item and 14-item parent-report forms have excellent internal consistency reliability, whereas the 7-item form has adequate to marginal reliability. The self-report 14-item form has good internal consistency reliability. For the interviewer form, construct validity has been demonstrated via factor analysis, with a general health factor emerging for all ages as well as a stagespecific factor (responsiveness for children younger than 2 years, activity for children 2 to 3 years old, and interpersonal functioning for children aged 4 years and older). The measure distinguishes between well and ill children across the age range and correlates with days in the hospital and days lost from school [43]. The self-report form has low to moderate correlations with measures of use, severity, or function [44]. Practicality. The measure is a proxy interview for ages 0 to 16 years. As an interview measure, the FSII(R) takes approximately 30 minutes [44] and requires an interviewer to administer. Thus, it is probably more expensive than the paper-and-pencil measures, but missing data are unlikely to be a problem. The measure lacks specific assessment of mental health and disease- and treatment-specific symptoms, and the factors are based on strictly behavioral indices of functioning from the parent’s perspective. Although the measure is intended for use up to age 16, it does not appear to have age-appropriate activity and development items for adolescents. The measure is available in English and Spanish. Conclusion Pediatric HRQOL measurement technology is still at an early stage of development. As such, consensus has yet to be reached among users of this technology regarding which instrument should be considered the gold standard. Health care decision makers interested in applying HRQOL measurement technology will benefit to the extent that they choose the technology appropriate for their needs. To facilitate the decision-making process, the authors offer the following guidelines: 1. The instrument should be practical, ie, reasonably short, easy to administer, easy to score, and easy to interpret. Vol. 6, No. 4

OUTCOMES IN PRACTICE 2. The instrument should have excellent reliability and validity. Evidence from peer-reviewed journal articles should be the standard for evaluation of the instrument’s measurement properties. 3. The instrument should demonstrate utility in diverse pediatric populations. Alarge normative database that includes the HRQOL scores of physically healthy children and adolescents is desirable for benchmarking and quality improvement purposes.

10.

11.

12.

13.

4. The instrument should permit patient self-report for a wide range of ages. Research has demonstrated that children as young as 5 years old can self-report their health and well-being [45]. Parent proxy-report should parallel child self-report. 5. It is preferable that the instrument employ a modular format that integrates a generic core scale with disease-specific modules, enabling decision makers to make comparisons with healthy population norms and to measure disease- and treatmentrelated symptoms with greater sensitivity and specificity. References 1. Mariner WK. Outcomes assessment in health care reform: promise and limitations. Am J Law Med 1994;20:37–57. 2. Guyatt GH, Feeny DH, Patrick DL. Measuring health-related quality of life. Ann Intern Med 1993;118:622–9. 3. Sprangers MA, Aaronson NK. The role of health care providers and significant others in evaluating the quality of life of patients with chronic disease: a review. J Clin Epidemiol 1992;45:743–60. 4. World Health Organization. Constitution of the World Health Organization basic document. Geneva, Switzerland: The Organization; 1948. 5. Coons SJ, Kaplan RM. Quality of life assessment: understanding its use as an outcome measure. Hosp Formulary 1993;28: 486–98. 6. Sprangers MA, Cull A, Bjordal K, Groenvold M, Aaronson NK. The European Organization for Research and Treatment of Cancer. Approach to quality of life assessment: guidelines for developing questionnaire modules. EORTC Study Group on Quality of Life. Qual Life Res 1993;2:287–95. 7. McHorney CA, Ware JE Jr, Lu JF, Sherbourne CD. The MOS 36-item Short-Form Health Survey (SF-36): III. Tests of data quality, scaling assumptions, and reliability across diverse patient groups. Med Care 1994;32:40–66. 8. Achenbach TM, McConaughy SH, Howell CT. Child/adolescent behavioral and emotional problems: implications of crossinformant correlations for situational specificity. Psychol Bull 1987;101:213–32. 9. Varni JW, Katz ER, Colegrove R, Dolgin M. Adjustment of

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Copyright 1999 by Turner White Communications Inc., Wayne, PA. All rights reserved.

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