INTRODUCTION
Vermiform appendix has surgical importance as it has tendency to undergo
inflammation and cause acute appendicitis. Acute appendicitis is most
common cause of acute abdomen in young adults and appendectomy is most
frequently performed urgent abdominal procedure1,2.
Epidemiologic studies have showed that approximately 50% (13-77%) of
the population will have appendicitis in their life
time3, with the peak incidence is in teens 20s, while
it’s rare in infancy and risk of acute appendicitis decreases after
middle age. Incidence is equal among males and females before puberty
and increases to 3:2 at age 25, thereafter greater incidence in males
decline.
No cause is yet confirmed but the factors responsible can be decreased
dietary fibers and increased consumption of refined carbohydrates
because incidence in developing countries is gradually increasing as
they are adapting more western lifestyle4.
The diagnosis is basically clinical along with lab findings. Therefore
combined scoring systems of both has devised to reduce negative
appendectomy rates(15-25%)5. Most widely used scoring
system is Alvarado scoring system , however RIPASA scoring system is new
development in recent years6.
The Raja Isteri Pengiran Anak Saleha Appendicitis (RIPASA) scoring
system was established in 2008 specifically for Asian populations. Chong
C F in his retrospective study consisting of 312 patients who had
undergone an emergency appendectomy between October 2006 and May 2008 in
Department of Surgery, Raja Isteri Pengiran Anak Saleha (RIPAS)
Hospital, Brunei Darussalem, concluded that optimal cut-off threshold
score for negative appendectomy was 7.5, with a sensitivity of 88%, a
specificity of 67%, a PPV of 93% and an NPV of 53%. The negative
appendectomy rate decreased significantly from 16.3% to 6.9%, which
was a 9.4% reduction (p is 0.0007)6.
Another study conducted at CMH Kohat by Muhammad Qasim Butt from sept
2011 to march 2012 showed that, out of 267 patients, positive cases of
acute appendicitis on histopathology were 152 and RIPASA score diagnosed
155 cases of acute appendicitis. True positive were 147, false positive
8, false negative 5, and true negative 107. Sensitivity of RIPASA score
was 96.7%, specificity 93.0%, diagnostic accuracy was 95.1%, positive
predictive was 94.8% and negative predictive was
95.54%3.
There is scarce local data available on this topic in our region and
internationally so, the aim of our study is to evaluate the diagnostic
accuracy of this new scoring system for presumptive accurate diagnosis
of acute appendicitis by taking histopathology as gold standard. This
study might be helpful in order to eliminate negative appendectomy rates
in our local population.
Materials and methods
This Cross sectional study was carried out at Surgery department of a
tertiary care hospital, Karachi. The study was conducted over a duration
of six months from 15th December 2019 to
15th June 2020. Non – probability consecutive
sampling technique was used. By using sample size calculator for
sensitivity and specificity by Dr. Lin Naig , statistics found as
follows3:
Sensitivity = 96.7%
Specificity = 93%
Prevalence of acute appendicitis = 50%
Margin of error for sensitivity = 4.2% and specificity = 6%
The calculated sample size came out as 141. Our inclusion criteria was :
(i) Both genders , Male/Female (ii) Age 15 – 50 years (iii) Suspected
cases of acute appendicitis presenting with pain right iliac fossa and
VAS(visual analog scale) score = 4 or more in emergency department
within 48 hours of onset of pain (score 1-3 = no to mild pain, score
3.1-6= mild to moderate pain, score 6.1-10= moderate to severe pain).
The exclusion criteria was : (i) Patient with co-morbid ( HTN , IHD ,
CLD , AKI , CKD , DM ) by taking detailed history (ii) Patients with
history of appendectomy confirmed by examination and previous medical
record (iii) Pregnant females confirmation by taking history (iv)
Diagnosed cases of appendicular abscess which are confirmed by detailed
examination and medical record of patients (ultrasound and CT scan). The
parameters of RIPASA scoring system are : age (≤ 40 years =1 point;
>40 years =0.5 point), gender (male = 1 point; female = 0.5
point), right iliac fossa (RIF) pain = 0.5 point, migration of pain to
RIF = 0.5 point, nausea and vomiting =1 point, anorexia =1 point,
duration of symptoms (≤48 hours = 1 point; >48 hours = 0.5
point), RIF tenderness =1 point, guarding = 2 points, rebound tenderness
=1 point, Rovsing’s sign = 2 points, fever =1 point, raised white cell
count = 1 point, negative urinalysis =1 point and foreign national
registration identity card =1 point. The cut-off limit of 7.5 points was
deemed as positive for acute appendicitis and was used as a diagnostic
tool7.
After approval by ethical review committee, patients were selected after
taking written informed consent prior to inclusion in study . Those
patients presenting in Emergency with pain right iliac fossa were
included. Patients underwent detailed history, general and physical
examination and scoring of patients according to RIPASA scoring scale
and then decision of appendectomy was taken on the basis of RIPASA
score. Patients were observed by same researcher to exclude
observer/interviewer bias. Patient’s particulars were noted and a
performa was filled and attached with admission form. Removed appendix
samples were sent for histopathology (Gold Standard), for confirmation
of acute appendicitis.
The data was analyzed using SPSS version 23. Mean and standard deviation
was calculated for age and RIPASA score. Frequency and percentage was
calculated for gender, education, findings on RIPASA and histopathology.
2×2 table was used to calculate sensitivity, specificity, PPV , NPV ,
diagnostic accuracy for RIPASA scoring system taking histopathology as
gold standard.
Effect modifiers like age, education, socio-economic status and gender
were addressed through stratification. Post stratification positive
predictive value(PPV) , negative predictive value(NPV) , diagnostic
accuracy(DA) , sensitivity and specificity was done.