Improved outcomes in ex-smokers with COPD: a UK primary care observational cohort study

Abstract

Smoking cessation in chronic obstructive pulmonary disease (COPD) reduces accelerated forced expiratory volume in 1 s decline, but impact on key health outcomes is less clear. We studied the relationship of smoking status to mortality and hospitalisation in a UK primary care COPD population.Using patient-anonymised routine data in the Hampshire Health Record Analytical Database, we identified a prevalent COPD cohort, categorising patients by smoking status (current, ex- or never-smokers). Three outcomes were measured over 3 years (2011-2013): all-cause mortality, respiratory-cause unplanned hospital admission and respiratory-cause emergency department attendance. Survival analysis using multivariable Cox regression after multiple imputation was used to estimate hazard ratios for each outcome by smoking status, adjusting for measured confounders (including age, lung function, socioeconomic deprivation, inhaled medication and comorbidities).We identified 16 479 patients with COPD, mean±sd age 70.1±11.1 years. Smoking status was known in 91.3%: 35.1% active smokers, 54.3% ex-smokers, 1.9% never-smokers. Active smokers predominated among younger patients. Compared with active smokers (n=5787), ex-smokers (n=8941) had significantly reduced risk of death, hazard ratio (95% confidence interval) 0.78 (0.70-0.87), hospitalisation, 0.82 (0.74-0.89) and emergency department attendance, 0.78 (0.70-0.88).After adjusting for confounders, ex-smokers had significantly better outcomes, emphasising the importance of effective smoking cessation support, regardless of age or lung function.

FIGURE 1

Distribution of smoking status by age at start of study. COPD: chronic obstructive pulmonary disease.

FIGURE 2

Distribution of age-specific smoking status categorised by severity of airflow obstruction: a) under 55 years, b) 55–64 years, c) 65–74 years, and d) 75 years and older. COPD: chronic obstructive pulmonary disease; GOLD: Global Initiative for Chronic Obstructive Lung Disease [19].