CAT and chronic bronchitis: Higher AM BC area was associated with worse respiratory morbidity including worse CAT (β = 1.04, 95% CI: 0.39,1.68), mMRC (β = 0.11, 95% CI: 0.02–0.19), SGRQ (β = 2.59, 95% CI: 1.13–4.05), increased cough and sputum (β = 0.43, 95% CI: 0.10–0.70), shorter 6MWD (β= -14.2, 95% CI: -17.2, -11.2) and greater odds of chronic bronchitis (OR = 1.50, 95% CI: 1.04–2.18) (Table 3).