Lack of generalizability of observational studies' findings for turnover time reduction and growth in surgery based on the State of Iowa, where from one year to the next, most growth was attributable to surgeons performing only a few cases per week.

STUDY OBJECTIVE: Three observational studies at large teaching hospitals found that reducing turnover times resulted in the surgeons performing more cases. We sought to determine if these findings are generalizable to other hospitals, because, if so, reducing turnover times may be an important mechanism for hospitals to use for growing caseloads.

DESIGN: Observational cohort study.

SETTING: 116 hospitals in Iowa with inpatient or outpatient surgery from July 1, 2013 through June 30, 2015.

SUBJECTS: Surgeons in Iowa, each with a unique identifier among hospitals.

MEASUREMENTS: The independent variable was the number of inpatient and outpatient cases that each surgeon performed each week during the first fiscal year beginning July 1, 2013. The dependent variables were surgeons' number of inpatient and outpatient surgical cases, and intraoperative work relative value units (RVU's) for outpatient cases, during the second fiscal year.

MAIN RESULTS: The average hospital in Iowa had less than half of its growth from year 1 to year 2 in numbers of cases among surgeons who performed >2 cases per week in the baseline year (23.0%±2.5% [SE], P<0.0001 comparing mean to 50%). Less than half the growth in RVU's was among those surgeons (18.1%±2.2%, P<0.0001). The average hospital in Iowa had less than half of its growth in numbers of cases among surgeons who performed 2 or fewer cases per week at the hospital during the baseline year and >2 cases per week at other hospitals in the state during that year (24.4%±2.6%, P<0.0001). Less than half the growth in RVU's was among those surgeons (21.3%±2.5%, P<0.0001).

CONCLUSIONS: Most (≥50%) annual growth in surgery, both based on the number of total inpatient and outpatient surgical cases, and on the total outpatient RVU's, was attributable to surgeons who performed 2 or fewer cases per week at each hospital statewide during the preceding year. Therefore, the strategic priority should be to assure that the many low-caseload surgeons have access to convenient OR time (e.g., by allocating sufficient OR time, and assigning surgeon blocks, in a mathematically sound, evidence-based way). Although reducing turnover times and anesthesia-controlled times to promote growth will be beneficial for a few surgeons, the effect on total caseload will be small.