Assessing the Volume-Outcome Hypothesis and Region-Level Quality Improvement Interventions: Pancreas Cancer Surgery in Two Canadian Provinces

Background. The volume-outcome hypothesis suggests that if increased provider procedure volume is associated with improved patient outcomes, then greater regionalization to high-volume providers should improve region-level outcomes. Quality improvement interventions for pancreas cancer surgery implemented in year 1999 in Ontario, Canada were designed to regionalize surgery to high-volume hospitals and decrease operative mortality. Similar interventions were not used in Quebec, Canada. We assessed the volume-outcome hypothesis and the impact of the Ontario quality improvement interventions. Materials and Methods. Administrative databases helped identify pancreatic resections from years 1994 to 2004 and relevant patient and hospital characteristics. Hospitals were high-volume if they provided >= 10 procedures in a given calendar year. Outcomes were regionalization of surgery to high-volume providers and rates of operative mortality. Results. From 1994 to 2004 the percentage of cases in high-volume hospitals increased from 33 to 71% in Ontario and from 36 to 76% in Quebec. Annual rates of operative mortality dropped in Ontario (10.4-2.2% or less) and changed little in Quebec (7.2-9.8%). Changes in measures over time in both provinces were similar before and after year 1999. Conclusions. Regionalization was associated with improved operative mortality in Ontario but not in Quebec, undermining the volume-outcome hypothesis. The Ontario quality improvement interventions likely were of little influence since patterns in regionalization and operative mortality were similar before and after year 1999.