BackgroundSome hospitals focus on a few types of procedures (i.e., the “focused factory model”), and some facilitate many different procedures being performed. Understanding the association between the diversity of procedures performed at a hospital and surgical workload (e.g., do focused factories experience greater growth) has implications for hospital management and operating room planning. MethodsThis observational cohort study used 2906 combinations of hospitals and years from the State of Texas for fiscal years 2005–2015. ICD-9-CM procedures studied were those with more than 7 American Society of Anesthesiologists base units. The discharges studied were those from hospitalizations with a DRG having a mean length of stay ≥4.0 days. The number of types of physiologically complex procedures commonly performed at each hospital was determined by calculating the inverse of the Herfindahl index (i.e., sum of squares of the proportions of all procedures of each type of physiologically complex procedure). ResultsHospitals’ percentage annual increases in total DRG relative weights (i.e., estimated costs) among discharges including a physiologically complex procedure were not associated with the diversity of performed physiologically complex procedures (slope −0.004%, 95% confidence interval −0.024% to 0.017%; P = 0.73). This lack of association was robust to alternative statistical model specifications. In addition, hospitals’ geometric mean annual proportional rates of growth of total DRG weights were uncorrelated with weighted average diversities (P = 0.31; Kendall's τb = 0.052; SE = 0.051). These results can be explained by the fact that hospitals performing a greater diversity of physiologically complex procedures had a relative distribution of different types of procedures more like the combination of all other hospitals in its health region than did hospitals with lesser diversity (τb = 0.627; SE = 0.012). ConclusionsPhysicians and administrators working at hospitals with a great diversity of types of physiologically complex procedures should not expect that adding new procedures to the hospital's portfolio will drive growth. They should expect growth, at most, minimally greater than that of smaller hospitals. Likewise, physicians and administrators at hospitals that specialize should be skeptical that a “focused factory” model contributes to more growth. Rather, one should expect growth to be no greater than at comprehensive hospitals.