Tables
- Table 1. Ancillary questions pertaining to the management of occupational asthma
What are the consequences of persistent exposure to the causal agent? Is it possible to improve symptoms and lung function by pharmacological treatment in affected workers with persistent exposure? What is the effectiveness of complete avoidance of exposure? What is the effectiveness of reducing exposure through engineering control or relocation of affected workers? What is the effectiveness of reducing exposure through personal protective equipment? Modified from [10], with permission from the publisher.
- Table 2. Comparison between persistence and avoidance of causal exposure
First author [ref.] Agent Persistence of exposure Cessation of exposure Symptom recovery NSBHR recovery Symptom recovery NSBHR recovery Chan-Yeung [13] Red cedar 0/47 NA 55/136 NA Rosenberg [14] Isocyanates 0/4 0/4 10/20 0/14 Moscato [15] Various 0/4 NA 9/18 NA Gannon [16] Various 2/34 NA 3/78 NA Tarlo [17] Isocyanates 0/10# NA 23/104# NA Orriols [18] Isocyanates 0/4 0/4 10/17 6/17 Merget [19] Platinum salts 0/9 NA 10/19 NA Valentino [20] Isocyanates 0/13 NA 9/37 NA Padoan [21] Isocyanates 2/13 NA 23/74 NA Pooled estimates¶ 4/138, 7.0% (3.4–13.7%) 0/8 152/503, 33.7% (23.6–45.6%) 6/31 Individual study data are presented as n/N. Pooled estimates are presented as n/N with or without % (95% CI). NA: not available; NSBHR: nonspecific bronchial hyperresponsiveness. #: “Global assessment of asthma”; ¶: pooled estimates based on a random-effect model.
- Table 3. Avoidance of exposure: characteristics and results of studies published between 2004 and 2010
First author [ref.] Country Agent Study design Duration of FU months Symptom recovery n/N Recovery of NSBHR n/N Brant [34] UK Enzymes Workforce-based survey of 35 out of 45 cases 37 (4–39) 5/35 NA Klusackova [35] Czech Republic Various Longitudinal FU of 37 cases (selection not stated) Clinic-based study 78 (12–216) 5/37 1/19 Labrecque [36] Canada Isocyanates Retrospective cohort study of compensated subjects (89 randomly selected subjects) ∼24 for all subjects 4/79¶ 10/79 Park [38] Korea Reactive dyes Longitudinal FU of 26 cases (selection not stated) Clinic-based study Second visit: 104±22 (n=19) NA 11/16 Park [37] Korea Reactive dyes Longitudinal FU of 11 cases (selection not stated) Clinic-based study 164±28 0/11 3/11 Pisati [39] Italy Isocyanates Longitudinal FU of 53 cases (selection of 25 patients rechallenged with TDI) Clinic-based study 58±7 (46–73) 10/25 12/25 Yacoub [40] Canada Various Retrospective cohort study of 40 compensated subjects 44±34 6/40 10/40 Munoz [41] Spain Persulfate salts Prospective longitudinal FU of 10 out of 11 cases Clinic-based study 63±19 (39–101) 2/7 5/7 Pooled estimates# 32/234, 15.5%¶ (8.3–27.1%) 52/197, 32.8% (16.8–54.3%) Data for individual studies are presented as mean (range), mean±sd or mean±sd (range), unless otherwise stated. Pooled estimates are presented as n/N with % (95% CI). FU: follow-up; NSBHR: nonspecific bronchial hyperresponsiveness; NA: not available; TDI: toluene diisocyanate. #: pooled estimates based on a random-effect model; ¶: the rate of symptom recovery was 19.2% (28 out of 155 subjects; 95% CI 11.2–30.9%) after exclusion of the study by Labrecque et al. [36], which used more stringent criteria of “clinical remission” defined by the absence of symptoms, NSBHR and medication.
- Table 4. Assessment of respiratory protective equipment (RPE)
First author [ref.] Design Agent Type of RPE Effects of RPE Muller-Wening [54] Laboratory challenge
Non-RCT study
n=26
Exposure: 1 h, not quantifiedOrganic farm allergens RPE with P2 filter: "Dustmaster" (n=21), "Airstream helmet" (n=4), "Airlite" (n=1) Suppression of symptoms in 11 out of 26, reduction in 15 out of 26, but 4 required inhaled bronchodilator
Reduction of the increase in airway resistanceLaoprasert [55] Laboratory challenge
RCT study with placebo
n=9
Exposure: 1 h, quantifiedLatex Laminar flow HEPA–filtered helmet Reduction of symptom score
Reduction of the decline in FEV1Slovak [56] Workplace exposure
Non-controlled study
n=8
Exposure: 6 weeks, not-quantifiedLaboratory animals Powered helmet respirator with AS-23-3 filter Worsening of symptoms in 2 out of 8 (score not available)
Peak flow variation at work in 2 out of 8Kongerud [57] Workplace exposure
RCT study
n=19 workers with nonsevere disease
Exposure: 2 weeks, not quantifiedAluminium pot room AH60 Airsteam helmet Reduction of symptom score in 10 out of 17 subjects (nonsignificant)
Improvement in the mean peak flow valuesTaivainen [58] Workplace exposure
Non-RCT study
n=24
Exposure: 10 months, not quantifiedFarming Powered dust respirator helmet with P2 filter No effect on respiratory symptoms with the exception of sputum, rhinitis symptoms, corticosteroid treatment, and number of sick leaves
Increase in morning peak flow and reduced daily peak flow variabilityRCT: randomised controlled trial; HEPA: high-efficiency particulate arrest; FEV1: forced expiratory volume in 1 s.
- Table 5. Recommendations
Recommendation Strength of recommendation Quality of evidence Patients, physicians, and employers should be informed that persistence of exposure to the causal agent is likely to result in a deterioration of asthma symptoms and airway obstruction Strong Moderate Patients and their attending physicians should be aware that complete avoidance of exposure is associated with the highest probability of improvement, but may not lead to a complete recovery from asthma Strong Moderate Reducing exposure to the causal agent can be considered an alternative to complete avoidance in order to minimise the adverse socioeconomic consequences, but available evidence is insufficient to recommend this option as a first-choice therapeutic strategy. This approach requires careful medical monitoring in order to ensure an early identification of asthma worsening Weak Low The use of respiratory protective devices should not be regarded as a safe approach, especially in the long term and in patients with severe asthma Strong Low Anti-asthma medications should not be regarded as a reasonable alternative to environmental interventions Strong Very low The pharmacological treatment of work-related asthma should follow the general recommendations for asthma Strong Moderate The strength of the recommendations and the quality of underlying evidence were graded using the Grading of Recommendations Assessment, Development and Evaluation approach [67].