Chest
Volume 107, Issue 3, March 1995, Pages 634-641
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Clinical Investigations: Irways: Articles
A Workers’ Compensation Claim Population for Occupational Asthma: Comparison of Subgroups

https://doi.org/10.1378/chest.107.3.634Get rights and content

Study objectives

(1) To compare patients with claims submitted to the Ontario Workers’ Compensation Board (WCB) for occupational asthma, in relation to the WCB decisions reached of occupational asthma (OA); aggravation of asthma from irritant exposures (AA); unrelated asthma; no asthma; and (2) to assess determinants of outcome of WCB accepted claims at permanent disability assessments.

Design

A retrospective review of 609 claims submitted to the WCB 1984 to 1988.

Results

The WCB decision reached was OA in 39% of claims, mostly attributed to isocyanates (57% of these). A further 39% were accepted for AA. Exposure to a known sensitizer occurred in 91% with OA and to an irritant in 67% with AA. Forty percent with AA were attributed to a spill or accidental exposure and 68% had preceding asthma. Those with AA were more likely to have clearing of symptoms by the time of their main assessment (43% vs 20% with OA) and were more likely to have remained in the same work (35% vs 20% with OA). Of 200 OA accepted claims reviewed at a mean of 1.9 years later, clearing of asthma occurred in 19% and milder asthma in 47%. Outcome was best with early diagnosis (p<0.05), and milder impairment of pulmonary function at initial assessment (p<0.05).

Conclusions

Patients with asthma induced by a workplace sensitizer demonstrate some differences from those related to workplace irritants. Accurate categorization and early removal of those with OA offers the best prognosis.

Section snippets

Material and Methods

Claims submitted for OA since mid-1984 to the Ontario WCB have been given a decision of (1) OA, (2) aggravation of asthma (c) unrelated asthma, or (d) other decision. The term aggravation of asthma (AA) was generally applied by the WCB to asthma that occurred at work, either with a history of preceding asthma or, in those with no known previous asthma, in the absence of a specific sensitizer. This included increased airway reactivity apparently triggered by irritant factors in subjects with no

Total Group

A total of 609 files was reviewed from the 4-year period. A diagnosis/decision of OA was reached in about one third of subjects both by the physician (35%) and the WCB (39%). A similar proportion (39%) was given a decision by the WCB of AA, and a diagnosis of this by the main assessing physician (34%). Of those with a WCB decision of AA, 68% had a history of preceding asthma. Unrelated asthma was diagnosed in 6% of the total group by the physician and 10% were given this decision by the WCB

Discussion

This survey reflects the claims received by the Ontario WCB for suspected work-related asthma, and may not necessarily reflect the true Ontario incidence or distribution of causative agents in the time period assessed, since many patients with OA may not be reported to the WCB or be eligible to submit a claim. Our categorization of patients into diagnostic groups has been on the basis of the WCB decision, stemming largely from the main physician assessment.

We recognize that the WCB decision may

ACKNOWLEDGMENT

The authors wish to thank Mary Harpur and Justina Greene for data gathering and processing, and Dr. C. Smith and Dr. P. Carr of the Ontario Workers’ Compensation Board for their cooperation in this study as well as Kerrie Cheung for typing assistance.

References (19)

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This study was supported by the Ontario Workers’ Compensation Board.

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