Gallbladder operations: a population-based analysis.

Cholecystectomy is one of the most frequently performed elective surgical procedures, and a major contributor to surgery-associated mortality. The well-documented variation in surgical rates across geographic areas has been attributed not simply to differences in disease prevalence but to factors such as varying rates of clinical and radiologic investigation and use of different indications for surgical treatment. The research uses a large claims-based data bank--the hospital and medical files maintained by the Manitoba Health Services Commission. The study focused first on the incidence of gallbladder operations in Manitoba's six rural and three urban areas. Age-adjusted surgical rates varied across regions from more than 50 operations per 10,000 persons aged 25 and over to less than 42. Such variation was considerably less than that noted earlier for the tonsillectomy/adenoidectomy (T&A) operation. Cholecystectomy and T&A rates were not significantly correlated across regions. Moreover, a region's cholecystectomy rate and its 'supply' of operating physicians (measured by a physician-to-population ratio) were not significantly associated. Because a large number of referrals to surgeons in urban centers take place, an analytical distinction between surgery done within the region and that done outside the region has been made. Some movement of rural patients with more serious conditions to urban hospitals is found. Questions of regionalization of surgery are discussed using 9 years of data on mortality following cholecystectomy and biliary tract surgery.