65 Comparison of Appendicitis Clinical Scoring Systems With Physician-Determined Likelihood of Appendicitis

Appendicitis is a common cause for abdominal pain in patients seen in the emergency department. While computed tomography often helps in the diagnosis, it also exposes patients to ionizing radiation, which increases their lifetime risk of cancer. In order to avoid this exposure, yet enhance the predictive power of history and physical exam, various clinical scoring systems have been developed. This study aims to compare the diagnostic accuracy of three clinical scoring systems for the diagnosis of appendicitis: the Alvarado score, modified Alvarado score, and Raja Isteri Pengiran Anak Saleha Appendicitis (RIPASA) score. Physician-determined likelihood of appendicitis was also evaluated. This is a HIPAA-compliant, IRB-approved prospective study of patients presenting with abdominal pain to an academic emergency department with an annual census of 48,000. Patients were eligible for enrollment if they were over 11 years old and had a computed tomography (CT) ordered to evaluate for appendicitis. For every enrollee, all clinical parameters needed to calculate the clinical scores were recorded by the assigned physician on a standardized data collection sheet prior to the patient going to CT. The assigned physician was also asked to estimate the likelihood of appendicitis: <40%, 40-60%, 60-80%, or >80%. Clinical scores were considered positive if ≥7.5 for the RIPASA Score and ≥7 for either the AS or MAS. The physician-determined likelihood of appendicitis was considered positive if >60%. We then calculated sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) for each score, reported as point estimates with 95% confidence intervals, using CT results as the reference standard. When CT results were equivocal, surgical findings or clinical follow-up were used as the reference standard. Cohen’s unweighted kappa values were also calculated for test pairs. We enrolled 236 patients from 2/2012-2/2014, including 142 (60.1%) women and 165 (69.9%) patients under age 40. The prevalence of appendicitis in this cohort was 35.6%. The AS had a sensitivity of 0.52 (0.46-0.59), specificity 0.74 (0.69-0.80), PPV 0.53 (0.47-0.59), and NPV 0.74 (0.68-0.79). The MAS had a sensitivity of 0.38 (0.32-0.44), specificity 0.82 (0.77-0.87), PPV 0.53 (0.47-0.60), and NPV 0.70 (0.65-0.76). The RIPASA score had a sensitivity of 0.75 (0.69-0.81), specificity 0.37 (0.31-0.43), PPV 0.40 (0.33-0.46), and NPV 0.73 (0.67-0.78). Physician-determined likelihood of appendicitis had a sensitivity of 0.64 (0.58-0.70), specificity 0.72 (0.66-0.77), PPV 0.56 (0.49-0.62), and NPV of 0.78 (0.73-0.84). Kappa values were 0.77 (0.69-0.86) for AS versus MAS, 0.35 (0.26-0.44) for AS versus the RIPASA score, 0.36 (0.24-0.48) for AS versus physician impression, 0.27 (0.20-0.35) for MAS versus the RIPASA score, 0.27 (0.15-0.39) for MAS score versus physician impression, and 0.38 (0.28-0.48) for the RIPASA score versus physician impression. None of the three clinical scoring systems were particularly sensitive or specific for the diagnosis of appendicitis, nor did they agree with each other or the physician’s impression. Further, physician clinical impression was as accurate as the scoring systems.