One evidence base; three stories: do opioids relieve chronic breathlessness?

The efficacy of low-dose systemic opioids for chronic breathlessness was questioned by the recent Cochrane review by Barnes et al. We examined the reasons for this conflicting finding and re-evaluated the efficacy of systemic opioids. Compared with previous meta-analyses, Barnes et al reported a smaller effect and lower precision, but did not account for matched data of crossover trials (11/12 included trials) and added a risk-of-bias criterion (sample size). When re-analysed to account for crossover data, opioids decreased breathlessness (standardised mean differences -0.32; -0.18 to -0.47; I-2=44.8%) representing a clinically meaningful reduction of 0.8 points (0-10 numerical rating scale), consistent across meta-analyses.