The categorisation of different causes of death in patients with chronic obstructive pulmonary disease (COPD) has not usually been regarded as an important topic, but with all-cause mortality and cause-specific mortality now being used as outcome measures in large multicentre clinical trials,^1,2 it is perhaps time to take stock of what we do and do not know about what patients with COPD actually die from. A number of studies that have addressed this issue over the years have, not surprisingly, found varying proportions of deaths ascribed to respiratory causes, lung cancer and cardiovascular disease (the three principal categories), with the results of any one study being highly dependent on both the source (and accuracy) of patient information and on the severity of underlying disease.^3–7

The past year has witnessed a flurry of papers and editorials covering a number of widely different aspects of mortality in COPD, with topics ranging from the confidence we can have in interpreting mortality data,⁸ the possible …