Trends in regionalization of adrenalectomy to higher volume surgical centers

Although centralization of surgical procedures to high volume centers has been described previously, patterns of care for adrenal surgery are largely unknown. We determined the extent of regionalization of care for adrenal surgery and the extent to which this centralization has evolved with time.

Using 1996 to 2009 hospital discharge data from New York, New Jersey and Pennsylvania we identified all patients 18 years old or older treated with adrenalectomy. Hospital volume quintiles were created using 1996 hospital volumes. These cutoffs were then applied to subsequent years. Outcome variables were examined by hospital volume status with time using logistic regression models.

A total of 8,381 patients underwent adrenalectomy from 1996 to 2009 with a significant 17% to 42% shift toward regionalization to very high volume hospitals, defined as 15 or greater procedures per year (p <0.001). For each successive year the odds of having surgery performed at a very low volume hospital decreased by 13% (OR 0.87, 95% CI 0.84-0.89). There were significant differences in patient age, race and payer group for very low volume hospitals, defined as less than 1 procedure per year, compared to very high volume hospitals (p <0.0001). Patients at very high volume hospitals were less likely to be 55 years old or older (OR 0.73, 95% CI 0.61-0.88), insured through Medicaid (OR 0.60, 95% CI 0.45-0.79) or uninsured (OR 0.34, 95% CI 0.17-0.70). When controlling for year treated, patients were less likely to die in the hospital if treated at a very high volume hospital (OR 0.38, 95% CI 0.19-0.75).

These data reveal the increasing centralization of adrenalectomy to very high volume hospitals since 1996 with improved clinical outcomes. Inequities in access to care to higher volume centers appear to exist and require further investigation.