|Year : 2022 | Volume
| Issue : 2 | Page : 158-162
Diagnostic test evaluation of Raja Isteri Pengiran Anak Saleha appendicitis score in patients with acute appendicitis
S Gowshika, S Santhosh Kumar
Department of General Surgery, Government Medical College, Thiruvananthapuram, Kerala, India
|Date of Submission||11-Nov-2022|
|Date of Decision||26-Nov-2022|
|Date of Acceptance||12-Dec-2022|
|Date of Web Publication||30-Jan-2023|
Dr. S Gowshika
Department of General Surgery, Government Medical College, Thiruvananthapuram - 695 011, Kerala
Source of Support: None, Conflict of Interest: None
Introduction: The diagnosis of acute appendicitis is still heavy reliant on clinical judgement as the availability and quality of imaging studies are quite variable. The Alvarado score and newer scores have been proposed in recent times, one of which is the Raja Isteri Pengiran Anak Saleha Appendicitis (RIPASA) score. It has been developed for a better diagnosis of acute appendicitis; the score includes 14 clinical parameters, which have higher sensitivity, specificity and diagnostic accuracy than Alvarado scoring, especially in the Asian population. Methodology: The objective was to evaluate the diagnostic accuracy of the RIPASA score with respect to histopathologically proven appendicitis. A diagnostic test evaluation was conducted in the surgical wards of a tertiary care centre for 1 year on patients undergoing emergency appendicectomy for acute appendicitis. Consecutive sampling was done on 132 participants. After administering the RIPASA score questionnaire to the patients, the histopathological reports were collected and the scoring system was compared to obtain sensitivity, specificity, predictive values, likelihood ratios and area under curve (AUC). Results: Of the 132 patients, 50.8% were male and 49.2% were female, with the majority of patients <40 years. Among components of the RIPASA score other than age, sex, anorexia, duration of symptoms and Rovsing's sign, all other components had an independent statistically significant association to histologically proven appendicitis. The receiver operating characteristic curve analysis of the RIPASA score showed an AUC of 0.915 (P < 0.0001). The negative appendicectomy rate was about 19.6%. Conclusion: The RIPASA score is a simple scoring system with high sensitivity and specificity for the diagnosis of acute appendicitis. The 14 clinical parameters are easily obtained from a good clinical history and examination and can be easily and quickly applied. Therefore, a decision on the management can be made early and complications can be prevented.
Keywords: Acute appendicitis, Raja Isteri Pengiran Anak Saleha Appendicitis score, Rovsing's sign
|How to cite this article:|
Gowshika S, Kumar S S. Diagnostic test evaluation of Raja Isteri Pengiran Anak Saleha appendicitis score in patients with acute appendicitis. Kerala Surg J 2022;28:158-62
|How to cite this URL:|
Gowshika S, Kumar S S. Diagnostic test evaluation of Raja Isteri Pengiran Anak Saleha appendicitis score in patients with acute appendicitis. Kerala Surg J [serial online] 2022 [cited 2023 Mar 24];28:158-62. Available from: http://www.keralasurgj.com/text.asp?2022/28/2/158/368593
| Introduction|| |
We usually compare the abdomen to Pandora's box for a good reason. Despite the vast advances in our medical field in terms of imaging and other investigation modalities, the importance of clinical examination cannot be stressed more.
Acute appendicitis is one of the most common causes of acute abdomen in any general surgical practice. It was first addressed by Reginald Heber Fitz in 1886., Since then, it has remained a topic of serial research works for various factors from its aetiology to its management options. It is a disease with a varying spectrum of presentations ranging from mild abdominal pain to catastrophic perforation. Thus, there exists a need for a valid investigation tool which helps in the diagnosis where individual clinical or laboratory findings may lack the diagnostic acumen.
Considering the above, the power of the Raja Isteri Pengiran Anak Saleha Appendicitis (RIPASA) score to categorise the patients to various risk strata makes it a valuable tool in the armamentarium of the surgeon to diagnose, triage and manage the patient. One of the most discussed and researched aspects relating to appendicitis is the one involving diagnosis. Over the years, different types of investigations, including laboratory and radiological, have been studied in detail with the help of many trials. These were conducted in the hope of finding the most sensitive test for diagnosing acute appendicitis. However, in spite of the vast advances in the field of medicine, it has been found by various clinicians and authors that appendicitis is a medical entity whose diagnosis is mainly based on clinical features. As quoted by Bailey and Love, 'Notwithstanding advances in modern radiographic imaging and diagnostic laboratory investigations, the diagnosis of appendicitis remains essentially clinical, requiring a mixture of observation, clinical acumen and surgical science'.
Following the development of the score, a randomised control trial was also done at the same hospital comparing the RIPASA and Alvarado scoring systems, and the former was found to be superior to the latter.
The primary objective of the study was to assess the diagnostic accuracy of the RIPASA score as against the histopathology in patients who have undergone emergency appendicectomy in a tertiary hospital. The secondary objective was to determine the rate of negative appendicectomies in the centre.
Having understood the importance of early and right diagnosis, and that clinical evaluation is the best and most accurate diagnostic modality for appendicitis; a wide range of clinical scoring systems have been developed over the past years. This has helped the clinician to a large extent in coming to the right diagnosis and providing early and appropriate management. This initially began as a single scoring system, and evolved into many over the years, as people proceeded with making many modifications to the existing scoring systems based on the local demographics or by adding more factors. Another problem is of finding the single best scoring system or the scoring system which has the maximum sensitivity and diagnostic accuracy. As a result, different types of studies have been done with randomised controlled trials comparing various scoring systems in different parts of the world.
Today, the most commonly used scoring system worldwide is the Alvarado and the Modified Alvarado scoring systems. The sensitivity and specificity for Alvarado scores vary from 53%–88% to 75%–80%, respectively. Hence, this is usually considered among clinicians worldwide as the undocumented gold standard scoring system. Today, any new scoring system that is developed is usually first compared to this.
The RIPASA score is a fairly newer scoring system, which was developed in 2008. It was identified through a study done in RIPASA Hospital, Brunei, Darussalam, to find a more favourable and better scoring system than the Alvarado and Modified Alvarado as these two were found to have poor sensitivity and specificity in Middle Eastern and Asian population. This is a simple qualitative scoring system.
| Methodology|| |
A diagnostic test evaluation was done for 1 year in the department of general surgery on patients who underwent emergency appendicectomy and had a histopathological examination. Patients who had an alternate pathology and patients <16 years of age were excluded.
The sample size was calculated using the formula n = (Zα2 × p × q)/d2 and N = n/x where, Zα = 1.96 for α at 0.05 p = sensitivity of the RIPASA score (95.5%) q = 100 − p d = max variability affordable, i.e., 4% (0.04) x = positive cases of appendicitis in histopathology report (HPR) (81.65%) N = 132 patients. Patients who met the study criteria were recruited consecutively to the study till the required sample size was met.
The RIPASA score had a total score – 17.5 calculated from 14 variables; (two demographics) age <40 years, sex (five clinical symptoms) right iliac fossa (RIF) pain, pain migrating to RIF, anorexia, nausea and vomiting, duration of symptoms more than 48 h, (five clinical signs) RIF tenderness, guarding, rebound tenderness, Rovsing's sign positive, fever >37°C or <39°C, (two investigations) raised white blood cell count, negative urinalysis and one additional parameter (foreign national identity card).
Histopathological report was a normal appendix, acute appendicitis neutrophilic infiltration into muscularis propria and acute suppurative appendicitis – microabscesses present and acute gangrenous appendicitis – the presence of haemorrhagic ulceration and necrosis/gross gangrene or perforation.
Data collection tool was a structured pro forma involving the laboratory and clinical parameters of the patients. After consecutively selecting patients admitted with a provisional diagnosis of acute appendicitis and undergoing emergency appendicectomy, the patient was clinically examined and laboratory parameters and histopathological report were collected and used as the gold standard. The diagnostic accuracy of each range of values of the RIPASA score signifying the levels of probability of acute appendicitis was assessed starting from the minimum cutoff score to the maximum score. The data were entered into an Excel spreadsheet and then analysed using the SPSS software, with the assessment of the sensitivity, specificity, receiver operating characteristic (ROC), positive predictive value (PPV) and negative predictive value (NPV) for analysing the diagnostic accuracy of each range of the score.
The study began after the approval of the Human Ethics Committee. Informed written consent was obtained from all participants. There was no financial burden to the patient. The privacy and confidentiality of participants were maintained.
| Results|| |
The study involved 132 patients with suspected appendicitis with 67 males (50.8%) and 65 females (49.2%). The age distribution of patients was mostly <40 years (75.8%) and rest >40 years (24.2%). Five patients had RIF pain (79.5%) and 94 had pain migrating to RIF (71.2%). Seventy-nine patients had a history of anorexia (59.8%) and 115 (87.1%) had a history of nausea and vomiting. About 57.6% of patients presented with a duration of symptoms <48 h. One hundred and nineteen patients (90.2%) had RIF tenderness and 72 (54.5%) had guarding in RIF. Seventy-two patients had rebound tenderness and 18 (13.6%) had Rovsing's sign positive. About 82.6% (109/132) had a history of fever and 78% (103/132) had raised total leucocyte count. About 63.6% (84/120) had negative urinalysis.
The RIPASA score was calculated for each patient and based on the score, there were 12 patients (9.1%) who were unlikely to be appendicitis (RIPASA score ≤5), 18 patients (13.6%) had a low probability of appendicitis (RIPASA score – 5-7.5) and 93 patients (70.5%) had a high probability of appendicitis (RIPASA score – 7.5-12). The histopathological analysis of 132 appendicectomy specimens showed that 106 specimens (80.3%) had features of appendicitis, whereas 26 specimens (19.7%) showed normal appendix. Hence, the negative appendicectomy rate in this study was 19.7%.
On comparing the predicted probability of acute appendicitis based on the RIPASA score and the histopathology results, it was found that out of 106 patients with histopathologically proven appendicitis, 84% of patients had a high probability of acute appendicitis (RIPASA – 7.5-12), 5.7% patients had a low probability of acute appendicitis (RIPASA – 5-7.5) and only 1.9% with (RIPASA score <5) unlikely to be appendicitis [Table 1].
|Table 1: Raja Isteri Pengiran Anak Saleha Appendicitis versus histopathology|
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On evaluating each component of the RIPASA score, the following results were obtained. Right lower quadrant pain had a statistically significant association to acute appendicitis (P < 0.05). Ninety-two patients (86.8%) with right lower quadrant pain had acute appendicitis in histopathology.
Migration of pain also had a statistically significant association to acute appendicitis (P < 0.05). Ninety-two patients (86.8%) with the migration of pain had acute appendicitis in histopathology. Nausea and vomiting also had a significant association with acute appendicitis (P = 0.002). Eighty-seven per cent of patients with nausea and vomiting had histologically proven appendicitis.
RIF tenderness also had a statistically significant association to acute appendicitis (P < 0.05). One hundred and three patients (97.2%) with RIF tenderness had acute appendicitis in histopathology.
The study proved that RIF guarding had a significant association with acute appendicitis (P < 0.05).
As per the study, rebound tenderness was also found to have a significant association with HPR (P < 0.005).
The study also proved Rovsing's sign had a significant association with appendicitis (P = 0.024).
The study also showed that fever has a significant association with appendicitis (P < 0.05).
Raised total count (TC) also had a statistically significant association with acute appendicitis (P < 0.05). Ninety-four patients (88.7%) with raised total count had acute appendicitis in histopathology.
Negative urinalysis also had a statistically significant association with acute appendicitis (P = 0.003). Sixty-one patients (57.5%) with negative urinalysis had acute appendicitis in histopathology.
Having seen the individual significance of each factor of the RIPASA score in predicting the presence of appendicitis, we move ahead with their cumulative strength as manifested by the RIPASA score [Table 2]. A ROC curve was constructed using the data collected from the study and the area under the curve was found to be 0.915, with P value being < 0.0001. Using the same sensitivities and specificities of the score at various values was analysed and the findings were as addressed in the subsequent tables.
|Table 2: Area under the receiver operating characteristic curve area under the curve|
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The sensitivity, specificity, positive predictive value and negative predictive value of each score were as shown in [Table 3].
|Table 3: Sensitivity, specificity, positive predictive value and negative predictive value on each Raja Isteri Pengiran Anak Saleha Appendicitis score|
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ROC curve analysis using HPR as the gold standard and the RIPASA scores as the predictor variable showed that the area under curve (AUC) is significant (AUC = 0.915; P < 0.0001). The analysis could be used to get two different cutoff values applicable in two different scenarios; one which gives more importance to sensitivity and another more importance to specificity. Based on the information presented in the above table, it is possible to say that an RIPASA score of 5 or above has 98.11% sensitivity to identify those having identified appendicitis. The specificity at this cutoff value was only 46.15%. Hence, for score <5, we can with high confidence rule out appendicitis.
At the same time, a RIPASA score of 9 or above has a specificity of 92.31%, but the sensitivity was only about 77.36%. Further, the PPV was determined to be 97.6, which indicates a strong predictor to diagnose acute appendicitis. The Youden Index (which enables a cutoff value with optimum sensitivity and specificity), also suggests a cutoff value of 7 (i.e. those who score above 7 could be diagnosed as having appendicitis).
The sensitivity, specificity, PPV and NPV were also calculated based on categorising RIPASA score into low probability, high probability and definite evidence of appendicitis [Table 4]. Based on this RIPASA score >7.5 had a sensitivity of 92.45%, specificity of 84.6%, PPV – 96.1 and NPV of 73.3%.
|Table 4: Sensitivity, specificity, positive predictive value and negative predictive value on categorising the Raja Isteri Pengiran Anak Saleha Appendicitis|
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| Discussion|| |
This study included 132 patients with suspected appendicitis and who underwent emergency appendicectomy. There were an equal number of females and males. The majority of patients belonged to the age group of <40 years. Among symptoms, RIF pain, migration of pain, anorexia, nausea and vomiting were present in the majority of patients.
Among clinical signs, RIF tenderness was the most common sign and was demonstrated in more than two-thirds of the patients. Guarding and rebound tenderness was present in more than half of the patients. More than three-fourths of the patients were febrile.
Laboratory investigations showed more than three-fourths of the patients with an increased total count and with negative urinalysis. In the present study, two-thirds of the patients were with the RIPASA score (7.5–12) – high probability to be appendicitis.
The negative appendicectomy rate in this study was 19.7%. The components of the RIPASA score other than age, sex, anorexia, duration of symptoms and Rovsing's sign were significantly related to the presence of appendicitis, as determined by histopathological examination. Among 106 patients with histologically proved appendicitis, more than two-thirds of the patients had RIPASA score – 7.5-12 (high probability to be appendicitis) and a very few patients had RIPASA score – <5 (unlikely to be appendicitis).
The ROC curve analysis of the RIPASA score showed an AUC of 0.915 (P < 0.0001). Rather than taking a dichotomising approach to determine a cutoff, we propose a graded approach with each score to make a sensible clinical decision. When a score of 7 or more taken as a cutoff, sensitivity, specificity and PPV were found to be 77.36%, 92.31% and 97.6%, respectively. Hence, in a patient with a score more than 7, we are justified in proceeding with an appendicectomy as the patient is more likely to have appendicitis.
When 5 is taken as a cutoff, the sensitivity, specificity and PPV was 98.11%, 46.15% and 88.1%, respectively. Hence, for score <5 we can with high confidence rule out appendicitis. Hence, it may be recommended to follow non-operative management in patients with the RIPASA score of <5.
These findings agreed with that of a prospective study conducted by Chong CF et al. in RIPAS Hospital, Brunei, between November 2008 and June 2009.
| Conclusion|| |
The RIPASA score is a simple scoring system with high sensitivity and specificity for or diagnosis of acute appendicitis. The 14 clinical parameters are easily obtained from a good clinical history and examination and can be easily and quickly applied. Therefore, a decision on the management can be made early and prevent complications. Using this score, unnecessary investigations and radiation risks are reduced, and simultaneously keep the negative appendicectomy rate as low as possible. This score is helpful in a situation where imaging facilities are not available. In patients with high RIPASA score, surgery is recommended without any further radiological investigations. Patients with intermediate score need radiological assessment to confirm the diagnosis of appendicitis. Patients with low score have to be clinically examined and looked for other causes of acute abdomen. The limitation of this study is that it included a very limited number of participants. The clinical signs elicited like guarding and rebound tenderness vary with the extent of analgesics and the clinician's experience.
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Conflicts of interest
There are no conflicts of interest.
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[Table 1], [Table 2], [Table 3], [Table 4]