Outcome of occupational asthma after cessation of exposure: a systematic review

Abstract

Background: Patients with occupational asthma, and their medical advisers, need valid information about the prognosis of their disease. Methods: A systematic review of the published literature on the symptomatic and functional outcomes of occupational asthma was carried out after avoidance of exposure to the causative agent. Through a full search of electronic and bibliographic sources, original studies documenting complete recovery from asthma (n = 39,1681 patients) or improvement in non-specific bronchial hyper-responsiveness (NSBHR; n = 28,695 patients) were identified. The median duration of follow-up was 31 (range 6-240) months for studies of symptomatic recovery and 37 (6-240) months for studies of NSBHR. Most studies were of patients recruited from special clinics. Results: Reported rates of symptomatic recovery varied from 0% to 100%, with a pooled estimate of 32% (95% CI 26% to 38%). These rates were lower with increasing age (p = 0.019) and among clinic based populations (p = 0.053). Patients with the shortest durations of exposure ((76 months) had the highest rate of recovery (36%; 95% CI 25% to 50%), but the effect was not linear. The pooled prevalence of persistent NSBHR at follow-up was 73% (95% CI 66% to 79%). This figure was higher among patients whose disease was due to high-molecular-weight agents (p = 0.006) and, less clearly, those from clinic-based populations (p = 0.561). In between-study comparisons, no clear patterns of improvement relating to total duration of exposure or follow-up were found. From within-study comparisons there was some evidence that a shorter duration of symptoms was associated with a higher rate of symptomatic recovery. Conclusion: The available data on the prognosis of occupational asthma are insufficiently consistent to allow confident advice to be given to patients with the disease. Clinicians and epidemiologists with an interest in this disease should consider a collaborative and carefully standardised study of the prognosis of occupational asthma.

Management of occupational asthma: cessation or reduction of exposure? A systematic review of available evidence

“…However, we analysed six studies [13-16, 19, 20] that were not included in the review of BEACH et al [7]. Noticeably, the cohorts of workers who avoided exposure that were selected in our review did not differ from those examined by RACHIOTIS et al [8]. The rates of BURGE [11] ROSENBERG [12] CHAN-YEUNG [13] MOSCATO [14] PISATI [16] MERGET [17] VANDENPLAS [18] BERNSTEIN [19] MUNOZ [20] Overall 28 BURGE [11] ROSENBERG [12] MOSCATO [14] PISATI [16] BERNSTEIN [19] Overall 28 symptoms and NSBHR recovery after cessation of exposure that were found in our review (38%, 95% CI 29-48%, and 29%, 95% CI 10-59%, respectively) were similar to those reported by RACHIOTIS et al [8] (32%, 95% CI 26-38%, and 27%, 95% CI 21-34%).…”

“…Moreover, we analysed the changes in symptoms and NSBHR after the interventions in a simple, categorical manner (i.e. recovery, improvement and worsening) as proposed by RACHIOTIS et al [8] in their systematic review of the outcome of OA after avoidance of exposure. Six [22,23,26,27,35,41] of the 10 studies [11,12,17,18,22,23,26,27,35,41] on workers with reduced exposure in the review by BEACH et al [7] were excluded from our analysis because they did not match our pre-defined inclusion criteria.…”

“…Considering the substantial heterogeneity of reported clinical and functional outcomes in follow-up studies of OA [7,8], it was a priori decided to restrict the analysis to the outcome of asthma symptoms and NSBHR, which were categorised as ''recovered'', ''improved'' or ''worsened'', according to the criteria used in each study. Data pertaining to socio-economic outcomes (employment, loss of income, healthcare costs and quality of life) were also gathered when available.…”

“…Abstracts of the retrieved papers were carefully analysed in order to identify original studies pertaining to the outcome of workers with ''lower'', ''reduced'' or ''intermittent'' exposures. The reference lists of relevant articles and previous systematic reviews [7,8] were screened in order to identify any additional publications.…”

Human Mesenchymal Stem Cells Resolve Airway Inflammation, Hyperreactivity, and Histopathology in a Mouse Model of Occupational Asthma

“…Nevertheless, pharmacological treatment has proven of limited utility [6]. Regarding OA caused by persulfate salts, it has been observed in a small number of patients that their condition seems to improve if they avoid exposure, although asthma symptoms and bronchial hyperresponsiveness may persist [7].…”