Factors associated with risk of moderate-to-severe exacerbation during the 12-months’ follow-up (negative binomial regression).

aReferent group always constitutes patients without the trait anytime in their history prior to dyspnoea index date. Abbreviations: CI, confidence interval; COPD, chronic obstructive pulmonary disease; GOLD, global initiative for obstructive lung disease; GP, general practitioner; MRC, Medical Research Council; QOF, UK National Health Service Quality and Outcomes Framework.