Regional variation in angiography, coronary artery bypass surgery, and percutaneous transluminal coronary angioplasty in Manitoba, 1987 to 1992: the funnel effect.

OBJECTIVES

Administrative data from Manitoba, Canada document variation in procedure utilization rates over a period of 15 years. With coronary angiography and cardiovascular surgery centralized in the capital, Winnipeg, previous analyses from 1977 to 1983 found angiography and coronary artery bypass surgery (CABS) rates to be higher for residents of Winnipeg. Residents of the Western region had consistently lower rates; this variation in regional access appeared due to physician practice patterns. In this study all angiography patients were followed from 1987 to 1992 and rates of CABS and percutaneous transluminal coronary angioplasty (PTCA) calculated.

METHODS

Cox proportional hazard multivariate regression models with five sociodemographic variables and two clinical variables (time from angiography to revascularization, and comorbidities) also were examined.

RESULTS

Consistent regional variation was documented; rates in the Western region remain consistently low. A "funnel effect" is found; the fewer patients from a region referred for angiography, the fewer patients from that region who have CABS or PTCA.

CONCLUSIONS

Implications of the persistence of these findings are discussed. Individuals in Western Manitoba probably have some of the lowest rates of coronary artery bypass surgery and percutaneous transluminal coronary angioplasty in North America.