Twenty-eight studies (9,330 participants) were included: two RCTs, 15 cohort studies and 11 studies that compared historical data collected before the widespread use of CT against data collected after the introduction of CT.
Negative appendectomy rates (10 pre/post CT comparisons, 20 CT/no CT comparisons): Incidence of negative appendectomy was significantly reduced after the introduction of CT (OR 0.52, 95% CI 0.36 to 0.76, I2=70%) and was also significantly lower in patients who received a CT scan compared to those who received clinical evaluation alone (OR 0.57, 95% CI 0.45 to 0.72, I2=32%). Removal of the historical comparison trial responsible for most of the heterogeneity had little influence on the summary estimate and heterogeneity remained.
Time to operating room (10 CT/no CT comparisons): Five studies reported a significantly longer time to operating room among patients who received CT. The mean waiting time was 7.8 hours for the clinical evaluation group and 13.3 hours for the CT group. Standard deviations were not reported.
Perforation rates (seven pre/post CT comparisons, eight CT/no CT comparisons): There was no significant difference in perforation rate between the pre-CT and CT era patients (p=0.74) or in patients who did or did not receive CT (p=0.15). There was no evidence of statistical heterogeneity (p=0.56 and 0.07).