TRENDS AND VARIATIONS IN THE USE OF VASCULAR-SURGERY IN ONTARIO

OBJECTIVE: To measure changes over time in overall surgical rates and geographic rate variations for three major vascular procedures (abdomi nal aortic aneurysm repairs, peripheral vascular disease procedures an d carotid endarterectomies). BACKGROUND: There is little research lite rature on population-based usage profiles of vascular procedures. The three procedures profiled were all subject to marked shifts in evidenc e or surgical opinions, raising the issue of the interplay between tem poral trends and geographic variations in their use. METHODS Based on Ontario's hospital discharge abstracts and census data, population-bas ed usage rates were calculated by site of patient residence from 1981 to 1991. Extent of rate variation was summarized with the coefficient of variation, systematic component of variation and the adjusted-likel ihood ratio chi(2). Spearman rank correlations were also calculated to assess stability of county rankings for each procedure. RESULTS: The overall rates of peripheral vascular procedures and repair for abdomin al aortic aneurysms fell 24% and increased 42%, respectively. The over all rate of carotid endarterectomies dropped from 46/100,000 in 1981 t o 20/100,00 in 1989, but by 1991 had increased to 37/100,000. Though t he decade measures of variation fell minimally for all three procedure s. CONCLUSION: Overall use of vascular procedures shifted in apparent response to new research evidence and technologies. Despite marked cha nges in surgical rates, the extent of geographic variation was stable, suggesting that differing factors influence overall surgical rates an d geographic rate variations. Audit at the local level using primary c linical data is needed to understand why disparities in use persist.