Physician and population determinants of rates of middle-ear surgery in Ontario

Context Small-area variations in surgical rates raise concerns about access to care, treatment appropriateness, and the quality and cost of care. Objective To measure small-area variations in rates of myringotomy with ins ertion of tympanostomy tubes (TTs) and to identify determinants of rate var iation. Design and Setting Retrospective analyses using hospital discharge data for patients who had undergone a myringotomy with insertion of TT by county in Ontario between April 1, 1996, and March 31, 1999. Information on possible determinants was taken from a survey of otolaryngologists and primary care physicians in 1996 and from the 1996 Canadian census and physician demogra phic databases for 1996-1999. Participants A total of 75 358 hospitalizations for TT placement of childre n and adolescents (aged less than or equal to 14 years). Main Outcome Measure Small-area variation in rates of TT. Results An almost 10-fold difference between the areas with the highest and lowest rates was found (extremal quotient, 9.6; 95% confidence interval [C I], 8.2-11.1; P<.001). Higher rates occurred in counties with higher percen tages of high school graduates (parameter estimate, 0.01; 95% CI, 0-0.02; P =.049); and where referring physicians were more likely to be male (paramet er estimate, 0.01; 95% CI, 0-0.02; P=.01), North American-trained (paramete r estimate, 0.01; 95% CI, 0.01-0.02; P<.001), and have higher propensities to refer for surgery (parameter estimate, 0.40; 95% CI, 0.09-0.72; P=.02). Otolaryngologist opinion was not a significant predictor. Conclusion Substantial area variation in TT rates was observed. The opinion of primary care physicians was the dominant modifiable determinant, sugges ting an area of research that may be important in reducing area variation i n TT procedures.