N-Acetylcysteine Treatment in Chronic Obstructive Pulmonary Disease (COPD) and Chronic Bronchitis/Pre-COPD: Distinct Meta-Analyses

Introduction: N-acetylcysteine (NAC) is a mucolytic agent with antioxidant properties. Oxidative stress is a key pathogenic mechanism in chronic respiratory conditions such as COPD and Chronic Bronchitis (CB). In these meta-analyses we investigated the efficacy of NAC in subjects with COPD or CB, the latter being a potential pre-COPD condition (CB/Pre-COPD)Methods: The meta-analyses were conducted according to PRISMA guidelines. Exacerbations were assessed using total number of exacerbations. Improvement in patients’ respiratory symptoms and/or patients Quality of Life (QoL) were measured by validated tools or assessed at the end of the study.Results: Twenty studies were included, of which seven evaluated NAC in patients with symptoms of CB/pre-COPD as entry criterion.NAC treated patients showed a significant reduction of the incidence of exacerbations as compared to placebo both in COPD (IRR=0.76 95% confidence interval (CI) 0.59 to 0.99) and CB/Pre-COPD (IRR = 0.81; 95% CI 0.69 to 0.95). Sensitivity analyses in studies with duration higher than 5 months, confirmed the overall results.CB/Pre-COPD patients treated with NAC were significantly more likely to experience an improvement in symptoms and/or QoL compared to placebo (Odds Ratio (OR) = 3.47 95% (CI) 1.92 to 6.26). A similar trend was observed in the few COPD studies evaluable.Sensitivity analyses showed a significant association of NAC with improvement in symptoms and/or QoL both in CB/Pre-COPD and COPD patients.Conclusions: These findings provide novel data of NAC on the improvement in symptoms and QoL in addition to prevention of exacerbations in COPD and CB/pre-COPD.PROSPERO registry no. CRD42023468154