Data Linkage to Estimate the Extent and Distribution of Occupational Disease: New Onset Adult Asthma in Alberta, Canada

Background Although occupational asthma is a well recognized and preventable disease, the numbers of cases presenting for compensation may be far lower than the true incidence. Methods Workers' Compensation Board (WCB) claims for any reason 1995-2004 were linked to physician billing data. New onset adult asthma (NOAA) was defined as a billing,for asthma (ICD-9 code of 493) in the 12 months prior to a WCB claim without asthma in the previous 3 years. Incidence was calculated by occupation, industry and, in a case-referent analysis, exposures estimated from an asthma specific job exposure matrix. Results There were 782,908 WCB eligible claims, with an incidence rate for NOAA of 1.6%: 23 occupations and 21 industries had a significantly increased risk. Isocyanates (OR 1.54: 95% CI 1.01-2.36) and exposure to mixed agricultural allergens (OR = 1.59: 95% CI 1.17-2.18) were related to NOAA overall, as were exposures to cleaning chemicals in men (OR = 1.91:95% CI 1.34-2.73). Estimates of the number of cases of occupational asthma suggested a range of 4% to about half for the proportion compensated. Conclusions Data linkage of administrative records can demonstrate under-reporting of occupational asthma and indicate areas for prevention. Am. J. Ind. Med. 52:83.1-840, 2009. (C) 2009 Wiley-Liss, Inc.