Is Negative Appendicectomy Rate a Key Factor for Diagnostic Accuracy of Various Scoring Systems?

Introduction

Acute appendicitis is a surgical emergency requiring appendicectomy. Urgent attention and prompt treatment are essential to prevent complications which sometimes become serious and even fatal. Acute appendicitis usually starts with pain near the umbilicus, which migrates to the right iliac fossa. Nausea and vomiting follow the pain with loss of appetite and mild fever. Acute appendicitis is most commonly caused by obstruction of the lumen of appendix by hard faecal matter called faecolith, or by lymphoid hyperplasia. 1 Acute appendicitis can occur at any age, but tends to be highest in the 10–20 age group. 2

Obstruction of the lumen of the appendix leads to congestion within the appendix, resulting in increased luminal pressure due to the secretion of inflammatory exudate and mucus. This obstructs lymphatic drainage, leading to further oedema, ulceration, bacterial growth and formation of pus. 3 Acute appendicitis is one of the most common causes of acute abdominal pain in adults and children, with a lifetime risk of 8.6% in males and 6.7% in females. 4 In the United States alone, approximately 300,000 hospital visits are reported annually related to appendicitis. 5

The negative appendicectomy rate (NAR) validates the diagnostic accuracy of scoring systems for acute appendicitis. The lower the NAR, the higher the accuracy of a scoring system. NAR indicates the capability of a scoring system to accurately diagnose acute appendicitis and differentiate it from other causes of abdominal pain.

An NAR of 0% by Nigam's Scoring System (NSS) surpasses all other scoring systems in diagnostic accuracy. In this study, we compared three important scoring systems for acute appendicitis i.e. Alvarado, Raja Isteri Pengiran Anak Saleha Appendicitis (RIPASA), and NSS, with respect to their diagnostic accuracy as measured by NAR. NAR of 5%–10% is usually accepted as normal by any scoring system, but in this study, high NAR values are not accepted. NAR should be as low as possible, as it directly reflects the ability of a scoring system to diagnose acute appendicitis accurately. A low NAR helps to avoid unnecessary appendicectomies and potential complications such as ileus, incisional hernias and increased cost to the patient. 6 Negative explorations can lead to longer hospital stays, higher costs, and increased morbidity and mortality as well. 7

Materials and Methods

This study was conducted at Max Hospital, Gurgaon, Haryana, India, which is a primary healthcare hospital. The study was performed from April 2014 to April 2026. A total of 85 cases were included in this research work. All cases of acute abdominal pain with suspicion of acute appendicitis were included in this single-centre study. Patients with abdominal pain without suspicion of acute appendicitis were not included in this study. All patients were treated on the basis of the score obtained by NSS. Demographics of all patients were recorded. A proper history and detailed physical examination were carried out for all patients along with basic laboratory tests. Scoring was done according to the variables in Table 1 and diagnosed as per Table 2.

Results

Out of 85 patients, 68 (80%) were male and 17 (20%) were female. The age of the patients varied from 15 to 72 years. Most of the patients had a normal body mass index (BMI). There were 6 (7.1%) patients who scored 6 or less than 6, 11 (12.9%) patients scored between 7–10, and 68 (80%) patients scored 11 and above. The patients who scored 6 or less were discharged with symptomatic treatment. Patients who scored 7–10 points were admitted for observation in the hospital and were operated on with laparoscopic appendicectomy when they did not improve. Sixty-eight patients who earned 11 and above were admitted, prepared for surgery and underwent appendicectomy without a period of observation in the ward. All samples of the excised appendix were sent for histopathological examination. All histopathology reports confirmed the diagnosis of acute appendicitis with various stages of inflammation. Thus, the NAR was 0% (Table 3).

Discussion

Christian GP et al. suggested that NAR is accepted as the measure of diagnostic accuracy of a scoring system for appendicitis. Clinical scoring systems to aid diagnosis have been described for acute appendicitis, but the cited studies are either computer-based or retrospective.11–13 Now, NSS has addressed this concern, as NSS diagnoses acute appendicitis with a high degree of accuracy rate without NAR (Figures 1 and 2).

Among the 249 patients from Australia (M = 113 and F = 136), the NAR was 9.7% in males and 3.9% in females.14 Another study from Bangalore reported NAR of 9% among 230 specimens. 15 The NAR was 8.7% in a Finnish study. 16 These rates of NAR are considered to be high and therefore, the diagnostic criteria or scoring systems used may need to be reconsidered and, if required, replaced with more effective methods. NSS has zero NAR, which should be the aim of all clinicians, even if more investigations and imaging techniques are used.

NAR is a key quality metric and parameter for evaluating the diagnostic accuracy of appendicitis scoring systems. A lower NAR indicates higher accuracy, with ideal systems aiming for < 15% or even lower with imaging. An ideal scoring system should aim for zero NAR, like NSS.

Low scores in various scoring systems where surgeries are performed due to fear of delay leading to perforation, are one of the main causes of high NAR. However, if these scoring systems are used cautiously and properly, then NAR can be reduced. Scoring systems are developed to diagnose acute appendicitis correctly and reduce the NAR or unnecessary appendectomies. Newer scoring systems have higher accuracy and lower NAR.17

The annual appendicectomy volume cited in the United States in 1997 was 250,000 cases with a negative NAR of 15%.18 In 2007 there were 3,26,000 appendicectomies.19 Several recent papers have reported a declining NAR, including large database studies and meta-analyses with NAR as low as 6%–8%,20,21 and single-institution studies with NARs as low as 1.7%–7%,22,23 coinciding with increased use of computed tomography (CT) and laparoscopy.24

NAR is the best parameter for assessing the diagnostic accuracy of a scoring system in acute appendicitis:

1. A high NAR is commonly due to diagnostic errors.
2. NAR clearly indicates the efficacy of a scoring system.
3. A high NAR is usually due to the use of an imperfect scoring system.
4. A high NAR is also due to over-cautious practice or fear of complications, such as perforation of the appendix.
5. A high NAR is also due to the fact that many surgeons accept a higher NAR than risk complications. They should devote more time and re-examine the patient after a few hours while the patient is kept under observation in hospital.
6. Appendicectomy in suspected cases without diagnostic confirmation is one of the reasons for a high NAR.

Declarations

Acknowledgements

The authors would like to thank Dr. Charvi Chawla for her efforts in arranging data and other information required for this research work. We are also thankful to Mr. Vipin Sharma for the preparation of the manuscript and transcription.

Declaration of patient consent
Informed consent was taken from the patients.

Financial support and sponsorship
None.

Conflicts of interest
The authors declare no conflicts of interest.