Mucolytics for Chronic Bronchitis
Mucolytics are designed to reduce the viscosity of lung secretions in patients with Chronic Obstructive Pulmonary Disease (COPD) and remain popular in many European countries but in the UK they are not available through NHS prescriptions. So how much difference do they make?
This Cochrane review located 23 suitable placebo controlled randomised trials of 10 oral mucolytic agents, including a total of over 4000 patients with Chronic Bronchitis or COPD. Not surprisingly there was little impact on lung function over the study period (most commonly six months of winter conditions), but a small but significant reduction occurred in the exacerbation rates. There was a Weighted Mean Difference (WMD) of 0.07 exacerbations per month (95% CI 0.08 to 0.05) and a reduction of the number of days of illness per month (WMD 0.56 days, 95% CI 0.77 to 0.35).
When considered as the proportion of patients who did not experience an exacerbation over the study period the Number Needed to Treat for one extra patient to be free from exacerbation was only 6 (95%CI 4 to 6). The authors say that clinicians and patients will need to judge for themselves whether the changes are large enough to warrant daily treatment for at least 3 to 6 months of the year. If you wish to discuss this with your patients you may find the illustration below could help them make up their minds.
The illustration shows that if one hundred patients with COPD are given mucolytics, 17 of them will be freed from exacerbation during the winter, but all hundred need to be treated as we do not know which are the 17 who will be helped. 44 would have been free from exacerbations anyway and 39 will still have at least one exacerbation in spite of the mucolytics.