Hospital variation in outcomes following appendectomy in a regional quality improvement program

The aim of this study was to determine hospital variation in clinical outcomes after appendectomy for acute appendicitis.

Using data from the Michigan Surgical Quality Collaborative, we selected patients with procedure codes for open or laparoscopic appendectomy with a diagnosis of acute appendicitis (2006 to 2011). We used multivariate regression models for risk adjustment of patient-level factors and reliability adjustment for sample size differences between hospitals. Adjusted rates of outcomes for each hospital were generated by multiplying ratios of observed to expected events by overall mean event rates.

During the study period, 12,410 patients underwent appendectomies in 49 participating Michigan Surgical Quality Collaborative hospitals. Neither the mortality rate nor the rate of superficial or deep surgical site infection demonstrated significant variation. However, significant variation was observed for all other clinical outcomes, including a 14-fold difference of the rate of postoperative sepsis and septic shock.

We found significant hospital variation in outcomes after appendectomy and identified missing variables that could help to explain the observed variation. These findings have been used to enhance ongoing quality improvement efforts across the state of Michigan.