Incremental costs of COPD exacerbations in GOLD stage 2+ COPD in ever-smokers of a general population

•The average annual disease-related costs for a COPD patient from a hospital register was twice as high as for a COPD case from a general population.•In a general population, moderate exacerbations fully explained all the costs of productivity losses for those with an FEV1 < 50% of predicted.•For the hospital sample, severe exacerbations explained a large part of the treatment-related costs, but not the costs of productivity losses.•Increasing severity of airflow obstruction was associated with increased costs in both samples.•Sampling source is of great importance when evaluating cost-of-illness studies of COPD.