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 insertion of tympanostomy tubes (TTs) and to identify determinants of rate variation. 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 demographic databases for 1996-1999. Participants A total of 75 358 hospitalizations for TT placement of children 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 [CI], 8.2-11.1; P<.001). Higher rates occurred in counties with higher percentages 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 (parameter estimate, 0.01; 95% CI, 0-0.02; P=.01), North American-trained (parameter 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, suggesting an area of research that may be important in reducing area variation in TT procedures.