Evaluating appendicitis scoring systems using a prospective pediatric cohort

Abstract

Study objective: This article evaluates the performance of the previously published Alvarado and Samuel appendicitis scoring systems in a prospectively identified pediatric cohort.

Methods: A prospective cohort of patients, aged 3 to 21 years, being evaluated for appendicitis was enrolled during 20 consecutive months at a large, urban, pediatric hospital. Study forms were completed by pediatric emergency medicine attending physicians before imaging or surgery. Final diagnosis was determined by pathology or follow-up telephone call. Each score was tested as proposed by the original authors. Sensitivity, specificity, and predictive values were calculated for all patients and prepubertal patients younger than 10 years.

Results: Five hundred eighty-eight patients were studied. The median age was 11.9 years (interquartile range [IQR] 8.5; 14.9 years). Thirty-four percent of patients had appendicitis. An Alvarado score greater than or equal to 7 yielded a sensitivity of 72% (95% confidence interval [CI] 66% to 78%), specificity 81% (76% to 84%), negative predictive value (NPV) 85% (81% to 89%), and positive predictive value (PPV) 65% (59% to 72%). A Samuel score greater than or equal to 6 yielded a sensitivity of 82% (77% to 87%), specificity 65% (60% to 70%), NPV 88% (84% to 91%), and PPV 54% (48% to 60%). When analysis was limited to patients younger than 10 years, n=206, an Alvarado score greater than or equal to 7 yielded a sensitivity of 73% (62% to 84%), specificity 80% (73% to 86%), NPV 89% (83% to 94%), and PPV 58% (45% to 69%). A Samuel score greater than or equal to 6, when patients younger than 10 years were considered, yielded a sensitivity of 77% (66% to 87%), specificity 65% (56% to 72%), NPV 88% (82% to 94%), and PPV 45% (35% to 55%). Receiver operator characteristic curves had an area under the curve of 0.83 (95% CI 0.79 to 0.86) (Alvarado) and 0.81 (95% CI 0.78 to 0.85) (Samuel).

Conclusion: Although the Alvarado and Samuel scores provide measurably useful diagnostic information in evaluating children with suspected appendicitis, neither method provides sufficient PPV to be used in clinical practice as the sole method for determination of the need for surgery.