Reduction of exposure to sensitising agents causing occupational asthma has been proposed as an alternative to total avoidance in order to minimise the adverse socio-economic impact of the condition. The aim of this systematic review was to compare the effects of these two management options on asthma and socio-economic outcomes. A bibliographic search was conducted to identify studies examining the outcome of workers with occupational asthma after reduction or cessation of exposure to the causal agent. The changes in asthma symptoms and nonspecific bronchial hyperresponsiveness after reduction or cessation of exposure were described in nine and five studies, respectively. The meta-analysis of pooled data showed that a reduction of exposure was associated with a lower likelihood of improvement (OR 0.16, 95% CI 0.03-0.91) and recovery (OR 0.30, 95% CI 0.11-0.84) of asthma symptoms and a higher risk of worsening of the symptoms (OR 10.23, 95% CI 2.97-35.28) and nonspecific bronchial hyperresponsiveness (OR 5.65, 95% CI 1.11-28.82), compared with complete avoidance of exposure. This systematic review indicates that reduction of exposure cannot be routinely recommended as an alternative to cessation of exposure in the management of occupational asthma. However, further investigations are required before drawing evidence-based conclusions on the cost-effectiveness of this approach.
