Validation of a diagnostic scoring system (Ohmann Score) in acute appendicitis

A diagnostic scoring system, recently published by Ohmann et al. in this jo urnal, was validated by analyzing the clinicopathological data of a consecu tive series of 2,359 patients, admitted for suspicion of acute appendicitis . The results of the scoring system were compared to the results of clinica l evaluation by junior (provisional) and senior surgeons (final clinical di agnosis). To assess the diagnostic ability of the score, the accuracy and p ositive predictive value were defined as the major diagnostic performance p arameters; the rate of theoretical negative laparotomies and that of diagno stic errors served as the major procedural performance parameters. Of 2,359 patients admitted for suspected acute appendicitis, 662 were proven to hav e acute appendicitis by histology, for a prevalence of 28 %. The overall se nsitivity, specificity, positive predictive value, negative predictive valu e, and accuracy of the provisional clinical diagnosis were 0.50, 0.94, 0.77 , 0.83, and 0.82; 0.93, for the score 0.63, 0.93, 0.77, 0.86 and 0.84, and for the final clinical diagnosis 0.90, 0.94, 0.85, 0.96, and 0.93, respecti vely. Of the main diagnostic performance parameter, the accuracy of the sco re was signifianctly better than that of provisional clinical diagnosis (P < 0.05, chi(2) test). The score yielded a rate of negative appendecomies an d laparotomies of 14.3 and 12.3 %. With respect to the rate of overlooked c ases of acute apendicitis, the score demonstrated a superior performance, w ith only 6 cases missed (0.9 %). However, the number of patients with acute appendicitis, including those with perforated disease, who were not identi fied by the score, was almost four times that of the final clinical diagnos is (245 vs 63). With regard to the main procedural performance parameter, t he score resulted in a significantly smaller number of diagnostic errors th an the provisional clinical investigator (P < 0.05, chi(2) test). The resul ts of this study indicate that the diagnostic scoring system might be helpf ul when experienced investigators or additional diagnostic modalities such as ultrasonography are not available. It may therefore be of value in the p reclinical evaluation of patients with suspected acute appendicitis and may be instrumental as a quality control tool and in clinical guidelines.