A cluster randomised controlled trial to reduce respiratory effects of cotton dust exposure among textile workers – the MultiTex RCT study

Background: We determined the effectiveness of an intervention to reduce cotton dust-related respiratory symptoms and improve lung function of textile workers. Methods: We undertook a cluster-randomised, controlled trial at 38 textile mills in Karachi. The intervention comprised: training in occupational health for all workers; formation of workplace committees to promote a health and safety plan that included wet mopping, safe disposal of cotton dust, simple face masks, and further publicity about the risks from cotton dust. Participating mills were randomised following baseline data collection. The impact of the intervention was measured through surveys at 3, 12 and 18 months using questionnaires, spirometry, and dust measurements. The primary outcomes were (1) changes in prevalence of a composite respiratory symptom variable; (2) changes in post-bronchodilator percentage-predicted forced expiratory volume in the first second (FEV1), and (3) changes in cotton dust levels. These were assessed using two-level mixed-effects linear and logistic regression. Results: Of 2031 participants recruited at baseline, 807 (40%) were available at the third follow-up. At that point, workers in the intervention arm were more likely to report an improvement in respiratory symptoms (OR=1.58; 95% CI: 1.06-2.37) and lung function (%predicted FEV1, β=1.31%; 95% CI: 0.04-2.57). Personal dust levels decreased, more so in intervention mills, although we did not observe this in adjusted models due to the small number of samples. Conclusion: We found the intervention to be effective in improving the respiratory health of textile workers and recommend scaling-up of such simple and feasible interventions in low- and middle-income countries.