Volume-based referrals do not necessarily improve patient outcomes

Referring patients to hospitals that have the largest volume of surgical procedures does not necessarily lead to improved outcomes for the overall population, according to the results of a new study in the February issue of the Journal of the American College of Surgeons.

The findings of studies that suggest the higher the volume of specialty surgical procedures performed at any given hospital, the better that hospital's outcomes will be, has resulted in calls for volume-based referrals. Most notably leading that call has been the Leapfrog Group's Evidence-Based Hospital Referral (EBHR) program, which launched a decade ago.

Researchers hypothesized that volume-based referrals would "regionalize" patients to hospitals meeting an EBHR volume metric and that, as a result, overall patient outcomes for these procedures would improve on a statewide basis. However, according to a new study in Washington State, the impact on patient outcomes across the state was negligible when a greater proportion of pancreatic and esophageal resections were performed at higher volume hospitals that met a given EBHR volume metric.

"This statewide analysis suggests Leapfrog's EBHR initiative has not had the intended impact of lowering the rate of adverse outcomes for all surgical patients having higher risk surgical procedures. Although there are many potential reasons for this finding, it may be the result of higher risk surgical patients not seeking care at higher volume centers," said Nader N. Massarweh, MD, MPH, a surgical resident at the University of Washington School of Medicine in Seattle and the study's lead author.

Comparing results before and after 2001 (2004 for pancreatic resection), the proportion of patients treated at hospitals meeting the EBHR volume metric for a given procedure increased for pancreatic (59.4% vs. 75.7%, p < 0.001) and esophageal resection (41.5% vs. 59.2%, p < 0.001), but was similar for abdominal aortic aneurysm (AAA) repair (16.3% vs. 17.6%, p = 0.13). In general, rates of adverse events were lower at hospitals meeting an EBHR volume metric. However, across Washington State and at non-EBHR centers, rates of mortality, readmission, and complications generally did not improve in the seven years following the introduction of the EBHR initiative.

The implications of Leapfrog's EBHR program for the health care system include: limiting patient flow and critically important revenue at smaller hospitals; decreasing surgeon competence and availability for emergency care at lower volume hospitals; providing fewer opportunities for surgical residency training at lower volume centers; and biasing patients toward higher volume centers for procedures not related to the EBHR initiative.

The consequences of referring patients to high-volume surgical centers are still being understood, but it appears as though doing so may not result in improved outcomes in the population as a whole.