Elsevier

Respiratory Medicine

Volume 105, Issue 9, September 2011, Pages 1364-1372
Respiratory Medicine

Time trends in occupational asthma in Belgium

https://doi.org/10.1016/j.rmed.2011.05.002Get rights and content
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Summary

Objectives

There is little information on the changes in the pattern of occupational asthma (OA) over time. The objective of this study was to evaluate the time trends in the incidence and causes of immunological OA in Belgium using workers’ compensation data.

Methods

Cases of OA were identified through a retrospective review of all claims submitted by salaried workers to the Belgian Workers’ Compensation Board from 1993 to 2002. The likelihood of OA was categorized as definite, probable, or possible based upon the results of from diagnostic procedures. Time trends were evaluated using Spearman’s rank correlation for crude numbers of cases and through the negative binomial regression for incidence rates of OA per industry.

Results

From a total of 1852 claims, 971 were categorized as having definite, probable, or possible OA. There was a downward trend in the annual number of cases due to the main causes of OA (i.e. flour, isocyanates, woods, and enzymes) and an apparent increase in cases of latex-induced OA. The estimated average annual incidence of OA was 29.4 (95% CI: 27.6–31.3) new cases per million salaried workers during the 1993–2002 period. There was a significant decline in the overall incidence rate of OA throughout the study period from 35.5 new cases per million salaried workers in 1993 to 25.8 in 2002.

Conclusions

These compensation-based data indicate that there has been a global downward trend in the incidence of OA during the nineties, although the factors that determined this reduced incidence should be further investigated.

Keywords

Asthma
Epidemiology
Occupational diseases
Prevention

Abbreviations

FEV1
forced expiratory volume in one second
HMW
high molecular weight
LMW
low molecular weight
OA
occupational asthma
PC20
concentration of histamine causing a 20% fall in FEV1
SIC
specific inhalation challenge
WCB
Workers’ Compensation Board

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