Benign hysterectomy performed by gynecologic oncologists: Is selection bias altering our ability to measure surgical quality?

Objective: To compare the characteristics of women undergoing hysterectomy for benign disease with either a benign gynecologist or a gynecologic oncologist and to assess for differences in complication rates with and without risk adjustment.

Methods: Patients undergoing benign hysterectomy recorded in the National Surgical Quality Improvement Program (NSQIP) targeted hysterectomy file in 2015 were identified. The primary outcome was any postoperative complication. Stratified analysis was performed by route of surgery. Bivariable tests and modified Poisson regression were used to adjust for confounding by procedure type and patient characteristics.

Results: We identified 17,639 patients who underwent hysterectomy for benign pathology, primary surgeon was a benign gynecologist (82%) or gynecologic oncologist (18%). Patients who underwent surgery with gynecologic oncologists were older (51yo v 46yo), had a higher mean BMI (32 v 30), and a higher prevalence of prior abdominal surgery (29% v 25%, p < 0.001), diabetes (10.6% v 7.0%), hypertension (34% v 25%) and higher ASA and Charlson comorbidity scores (p < 0.001, for all). For laparoscopy, surgery with a gynecologic oncologist was associated with a decreased risk of complication (RR 0.80, 95% CI 0.66-0.98). For laparotomy, surgery with a gynecologic oncologist was associated with an increased risk of complication (RR 1.18 95% CI 1.01-1.38), however, this was no longer the case with risk adjustment (aRR 0.90, 95% CI 0.76-1.07).

Conclusions: Patients operated on by gynecologic oncologists have a higher prevalence of risk factors for complication compared to those operated on by benign gynecologists even with a benign indication for surgery. Quality measurement should account for this selection bias.