Prevalence and Incidence of Diagnosed Chronic Rhinosinusitis in Alberta, Canada

IMPORTANCE Reported prevalence rates of chronic rhinosinusitis (CRS) range from 1% to 12% worldwide. To facilitate appropriate health service delivery and resource allocation, it is important to improve the estimated burden of CRS to the health care system. OBJECTIVES To assess the prevalence and incidence of diagnosed CRS in Alberta, Canada, from the perspective of the health care system and to evaluate the 10-year temporal trend and geographic variation of diagnosed CRS. DESIGN, SETTING, AND PARTICIPANTS From provincial-wide physicians' claim data, a CRS cohort was identified using a validated case definition. The population at the midpoint (2008-2009) of the study period (2 925 930) was used as the reference. The crude as well as age-and sex-standardized incidence and prevalence rates were calculated. The age-specific incidence and prevalence by sex were also assessed in each study year. Small-area variation analysis was conducted using extremal quotient, weighted coefficient of variation, chi(2) statistic, systematic component of variation, and empirical Bayes variance estimate. RESULTS Of the 2 925 930 individuals in the study at midpoint (2008-2009), 1 451 261 (49.6%) were women, and the mean (SD) age was 45 (17) years. From fiscal year 2004-2005 to fiscal year 2013-2014, the mean age-and sex-standardized incidence of diagnosed CRS was 2.5 (range, 2.3-2.7) per 1000 population. The estimated prevalence based on age-specific incidence varied between 18.8 (95% CI, 18.7-18.9) and 23.3 (95% CI, 23.1-23.5) per 1000 population during 2004-2005 to 2013-2014, and no obvious growing trend was found. There was high geographic variation in the diagnosed incidence and prevalence of CRS (mean systematic component of variation, 19.4 and 12.3, respectively). CONCLUSIONS AND RELEVANCE Although the incidence and prevalence rates of diagnosed CRS were lower compared with earlier published estimates obtained from population-based survey analysis, outcomes from this study may more accurately reflect the disease burden of CRS to the health care system. Given that the prevalence of CRS within a single province is expected to be uniformly distributed, the large geographic variation in diagnosed CRS indicates a potential gap in quality of care and justifies further investigation into the reasons for the variation.