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.