Linkage of administrative and compensation databases for work-related asthma surveillance in Ontario: a proof of concept study

Rationale — Approximately 15% of all asthma cases are work-related and eligible for workers’ compensation in Ontario. However, compensation rates of work-related asthma (WRA) are far less than predicted, making it difficult to estimate the prevalence of the disease.

Objectives — We aimed to estimate prevalence of compensated WRA in Ontario; profile the pattern of compensated WRA by demographic, temporal and geographic factors; and demonstrate the potential for database linkage to monitor rates of compensated WRA cases.

Methods — Compensated WRA claims data were linked to asthma cases in the Institute of Clinical Evaluative Sciences (ICES) asthma database via encrypted health card numbers. WRA claims between April 1998 and March 2002 were accessed from: i) the Ontario Workplace Safety and Insurance Board (WSIB) Occupational Disease Information Surveillance System (ODISS); and ii) a University of Toronto research database (RD) created by abstracting the same WSIB ODISS claim files.

Main Results — The estimated prevalence of WRA among individuals with asthma in the asthma database was less than 1% compared to an expected prevalence of 15-20%. Sensitivity of the Asthma database for including individuals with asthma with WRA was very good but differed significantly based on claims category (p < 0.001) compared to the RD as the gold standard.

Conclusions — Our findings suggest WRA is severely under-reported. Approximately 11-15% of compensated WRA claims are not captured by the asthma database. Factors accounting for discordance between databases should be explored in order for administrative data linkage to be used to monitor the rates of compensated WRA cases in Ontario.