Validating the Concept of COPD Control: A Real-world Cohort Study from the United Kingdom

The concept of Chronic Obstructive Pulmonary Disease (COPD) control has been developed to inform therapeutic decision-making. We explored the validity of a definition of COPD control in a representative population of patients with COPD in the United Kingdom. Electronic medical records and linked COPD questionnaire data from the Optimum Patient Care Research Database were used to characterize control status. Patients were aged ≥40 years, with spirometry-confirmed COPD, current or ex-smokers, and continuous records throughout the study period. Control was evaluated based on COPD stability and patients' (i) clinical features or (ii) COPD Assessment Test (CAT) score over a three-month baseline period and linked to time to first exacerbation. Of 2788 eligible patients, 2511 (90%) had mild/moderate COPD and 277 (10%) had severe/very severe COPD based on Body Mass Index, Obstruction, Dyspnoea, Exacerbations (BODEx) cut-off of 4. Within the mild/moderate cohort, 4.5% of patients were controlled at baseline according to clinical features and 21.5% according to CAT threshold of 10. Within the severe/very severe cohort, no patients were controlled at baseline according to the proposed clinical features and 8.3% were controlled according to CAT threshold of 20. Compared with uncontrolled patients, time to first exacerbation was longer for controlled patients with mild/moderate COPD but not for those with severe/very severe COPD. Lowering the BODEx threshold for severity classification to 2 increased the number of patients achieving control. CAT scores were not good predictors of the risk of future exacerbation. With the proposed definition, very few patients were defined as controlled.