Case definitions for chronic rhinosinusitis in administrative data: A systematic review

Background: The use of administrative data for pharmacoepidemiologic research on chronic rhinosinusitis (CRS) has become increasingly popular. Although large sample sizes and ease of accessibility have made electronic health data an attractive data option, the risk of inaccurate cohort identification can lead to biased outcomes. Objectives: The objectives of this systematic review were to (1) report current case definitions for CRS used in administrative data base research, and (2) define the various administrative data bases used for CRS research. Methods: Medical literature data bases were searched from the date of their inception to February 1, 2015. Included studies were publications that obtained CRS-specific data from a health records data base. Studies were excluded if they evaluated a non-CRS cohort, failed to use or report an international classification of disease (ICD) code in the case definition, or published in a non-peer-reviewed journal. Results: Of the 27 studies that met inclusion criteria, 8 different CRS case definitions were identified and 13 administrative data bases were evaluated. Of the 8 different CRS case definitions identified, only one was validated. The most commonly used CRS case definition was the ICD-9 473.x code alone. Conclusion: To optimize the accuracy of pharmacoepidemiologic research for CRS that used administrative data, it is important to apply appropriate case definitions for CRS. Various nonvalidated CRS case definitions are currently being used in administrative data base research. There is a need to develop a generalizable and validated ICD-based CRS case definition to increase the accuracy of future pharmacoepidemiologic research.