Hospital morbidity rankings and complication severity in vascular surgery

The American College of Surgeons National Surgical Quality Improvement Program ranks hospitals according to risk-adjusted rates of postoperative complications. However, this approach does not consider the severity or number of complications that occurred. We sought to determine whether incorporating this information would alter hospital rankings.

The study examined data for the 39,519 patients who underwent major vascular surgery in 206 National Surgical Quality Improvement Program hospitals during 2008 to 2009. We categorized postoperative complications as minor or severe and evaluated the extent to which minor and severe complications increased a patient's risk of death and prolonged length of stay. We then ranked hospitals on two alternative approaches that included severity or number of complications. We determined the effect of these alternative methods by assessing the proportion of hospitals that moved out of the top and bottom 20% of hospitals compared with standard rankings.

Compared with patients with minor complications, patients with severe complications had a higher mortality rate (16.2% vs 3.6%; P<.001) and prolonged length of stay (66.7% vs 53.3%; P<.001). Patients with two or more complications also had a higher mortality rate (23.7% vs 6.0%; P<.001) and prolonged length of stay (77.0% vs 50.1%; P<.001) than patients with only one complication. Compared with the current approach for assessing morbidity, ranking hospitals by severe complications resulted in 12 hospitals (29%) moving out of the top 20% and 10 hospitals (24%) moving out of the bottom 20%. A similar degree of reclassification was found when the current rankings were compared with an alternative approach that considered the number of different complications.

Although the severity and number of postoperative complications affect mortality and length of stay, and subsequently, hospital rankings, existing measurement systems do not take this into account. Quality measurement platforms should consider weighting complications according to severity and number.