Original Article

Brunei Int Med J. 2010; 6 (1): 17-26

Evaluation of the RIPASA Score: a new scoring system for the diagnosis of acute appendicitis Chee Fui CHONG 1, Amy THIEN 1, Ahamed Jiffri AHAMED MACKIE 1, Aung S TIN 1, Sonal TRIPATHI 1, Mohammad Addy A AHMAD 1, Lian Tat TAN 1, Firdaus Mohamad MAT DAUD 1

, Caroline TAN 1, Pemasiri Upali TELISINGHE 2, Swee Hui ANG 3,

1

Department of Surgery, 2Department of Pathology and 3Department of Accident and

Emergency, RIPAS Hospital, Brunei Darussalam

ABSTRACT Introduction: We recently developed a scoring system for diagnosis of acute appendicitis. This study prospectively evaluates the Raja Isteri Pengiran Anak Saleha Appendicitis (RIPASA) score for the diagnosis of acute appendicitis in patients presenting to the Accident and Emergency department or the Surgical wards with right iliac fossa pain. Materials and Methods: From November 2008 to April 2009, consecutive patients presenting to the Accident and Emergency department or the surgical wards with right iliac fossa pain were recruited for the study. The RIPASA score was applied but the decision for radiological investigations or emergency appendicectomy was made based on clinical judgement. Receiver operating curve (ROC), sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of the new scoring system were derived. Ethical approval for the study was obtained from the Medical and Health Review Ethics Committee. Results: Within six months, 144 consecutive patients with a mean age of 29.5 ± 13.3 yrs were recruited to the study. Ninety-eight patients underwent emergency appendicectomy of which 79 were confirmed histologically for acute appendicitis. The observed negative appendicectomy rate was 19.4%. The optimal cut-off threshold score from the ROC was 7.5, with a sensitivity of 97.5%, specificity of 81.8%, PPV of 86.5%, NPV of 96.4% and a diagnostic accuracy of 91.8%. The predicted negative appendicectomy rate was 13.5%, which is a 5.9% reduction from the observed rate of 19.4% (p=0.3). Conclusion: The RIPASA score is a more suitable appendicitis scoring system developed for our local settings with a population that is reflective of our region in South-east Asia and has high sensitivity, specificity and diagnostic accuracy.

Keywords: Acute appendicitis, appendicectomy, diagnostic techniques, surgical, symptoms

INTRODUCTION Acute appendicitis is one of the most common

an estimated life time prevalence approxi-

surgical emergencies in clinical practice, with

mately 1 in 7. 1 The incidence is 1.5 to 1.9 per 1000 in male and female with approximately

Correspondence author: Chee Fui CHONG Department of Surgery (Cardiothoracic Division), RIPAS Hospital, Bandar Seri Begawan BA 1710, Brunei Darussalam. Tel: +673 2242424 Ext 6280, Fax: +673 2242690 E mail: [email protected]

1.4 times greater in men than in women.2

Diagnosis

of

acute

appendicitis

is

based purely on clinical history and examina-

CHONG et al. Brunei Int Med J. 2010; 6 (1): 18

tion combined with a few laboratory investi-

MATERIALS AND METHODS

gations such as elevated white cell count.

Patients: 144 consecutive patients present-

Despite being a common problem, acute ap-

ing to the Accident and Emergency depart-

pendicitis remains a difficult diagnosis to es-

ment (AED) or the Department of Surgery at

tablish in some cases, particularly in the

Raja Isteri Anak Saleha (RIPAS) Hospital from

young, elderly and female patients of repro-

November 2008 to April 2009, with RIF pain

ductive age where a host of other genitouri-

were recruited for the study. All patients of all

nary and gynaecological inflammatory condi-

age groups presenting with RIF pain, sus-

tions can also present with similar signs and

pected to be acute appendicitis were included

3

Several

in this study. Patients presenting with non-RIF

scoring systems have been developed to aid

pain and those who have been admitted by

in the decision making process of deriving a

other specialties for other complains but who

diagnosis of acute appendicitis in the fastest

subsequently developed RIF pain were ex-

and cheapest way. The ‘Alvarado score’ and

cluded from the study. Ethical approval to

the ‘Modified Alvarado score’ are the two

conduct the study was granted by the Medical

most commonly used scoring system avail-

and Health Review Ethics Committee (MHREC)

symptoms

4,5

able.

of

acute

appendicitis.

Reported sensitivity and specificity for

at RIPAS Hospital.

both Alvarado and the Modified Alvarado scores ranges from 53 to 88% and 75 to 80% 4,5

respectively.

However, these scoring sys-

Scoring of RIPASA score sheet: Prospective evaluation of the RIPASA score was done

tems were developed in western countries

by

and several studies have reported very low

(Appendix). The score sheet does not con-

sensitivity and specificity when applied to a

tained the actual scores for each parameter in

population with a completely different ethnic

order to avoid the total score biasing the

origin and diet.6-8

judgement of the admitting surgeon in his/her

the

completion

of

the

score

sheet

decision making with respect to appendicecThe Raja Isteri Pengiran Anak Saleha

tomy, which was still solely based on the sur-

Appendicitis (RIPASA) score is a simple quali-

geon’s own clinical judgement for this pro-

tative scoring system based on 14 fixed clini-

spective evaluation study.

cal parameters (two demographics, five clinical symptoms, five clinical signs and two clini-

Initial scoring was performed by an

cal investigations) and one additional pa-

AED senior medical officer (SMO) if the pa-

rameter (foreign national Identity card) as

tient is seen in the AED. Scoring thereafter

shown in the Appendix. We recently reported

will be carried out by the admitting surgeon

our retrospective

when the patient is admitted to the surgical

analysis

of

the

RIPASA

score which showed a sensitivity and specific-

ward

ity of 88% and 67% respectively with a diag-

directly to the admitting surgical team by the

9

or

if

the

patient has been referred

In this study, we

general practitioner. Only scores derived by a

report on the prospective evaluation of the

surgeon of senior grade (Post membership

RIPASA score in patients presenting with right

SMO or equivalent registrar or consultant) will

iliac fossa (RIF) pain.

be considered.

nostic accuracy of 81%.

CHONG et al. Brunei Int Med J. 2010; 6 (1): 19

Scoring was performed at every re-

Statistical

Analysis:

Receiver

operating

view; either two hourly or at the next morn-

curve (ROC) at the optimal cut-off threshold

ing ward round if the patient’s was admitted

score for the RIPASA score was derived using

in

early hours of the morning, until a

StatsDirect statistical software version 2.7.2

decision was made for either appendicectomy

(StatsDirect Ltd, Cheshire, UK 2008). Sensi-

or continued conservative observation/treat-

tivity, specificity, positive predictive value

ment. Completed forms were collected by the

(PPV), negative predictive value (NPV) and

ward clerk and kept in a folder specifically for

diagnostic accuracy at the optimal cut-off

the study. There were later collected by the

threshold score were also derived from the

study coordinator at regular intervals.

ROC.

the

Predicted

negative

appendicectomy

rates for the RIPASA score was also derived Data regarding patients’ admission

and compared with the observed negative

and discharge dates, date of appendicectomy

appendicectomy rate using the Chi-square

if performed, name and signature of confirm-

test for statistical analysis.

ing

surgeon,

post-operative

complications

and use of radiological investigations were

RESULTS

recorded in the score sheet. All histological

Demographic and operative details for the

confirmation of appendicular specimens ob-

144 study patients are shown in Table 1. The

tained from emergency appendicectomy were

mean age of the group was 29.5 ± 13.3 years

reviewed by a single senior pathologist at

with slightly more female (male:female ratio,

Department of Pathology, RIPAS hospital.

1:1.3).

Patients who were treated conserva-

Ultrasound investigations were per-

tively and subsequently discharged were re-

formed in only 25.7% of all patients with ma-

viewed once in the surgical out-patient clinic

jority (81.8%) performed in female patients

a week after discharge. Patients who were

(Table 1) and 62.2% were in patients with

discharged from the AED were reviewed at

score 7.5

cantly more RIPASA score readings performed

(true positive). Only two cases with positive

than the true positive and false positive

appendicitis had RIPASA score 7.5 (false positive) and

emergency appendicectomy. Those with mul-

seven were in patients with RIPASA score

tiple readings, the trend of the total score re-

7.5 Sample size (n)

Median number of scores taken (range)

True –ve