Gut, microbiota-dependent trimethylamine-N-oxide is associated with long-term all-cause mortality in patients with exacerbated chronic obstructive pulmonary disease.

•The gut, microflora-dependent metabolite trimethylamine-N-oxide (TMAO) is associated with mortality in patients with chronic obstructive pulmonary disease.•The prognostic value of TMAO was independent of type of exacerbation.•Comorbidities and age had a strong influence on TMAO levels.•Whether nutritional interventions influence TMAO warrants further investigation.