Use of mortality within 30 days of a COPD hospitalisation as a measure of COPD care in UK hospitals.

Mortality rate has been proposed as a metric of hospital chronic obstructive pulmonary disease (COPD) care in light of variation seen in national COPD audits. Using Hospital Episode Statistics (hospital 'coding') we examined 30-day mortality after COPD hospitalisation in 150 UK hospitals during 2006-2007 and 2007-2008. Mean and median 30-day mortalities were similar each year but the coefficient of variation was >20% and hospitals could change from a low or high quartile to the median by chance. We could not detect any reasons for hospitals being at the extremes. 30-day mortality after COPD hospitalisation is a complex variable and unlikely to be useful as a primary annual COPD metric.