Pattern of Cardiovascular Comorbidity in COPD in a Country with Low-smoking Prevalence: Results from Two-population-based Cohorts from Sweden
Cardiovascular diseases are the most common comorbidities in COPD, due to common risk factors such as smoking. The prevalence of current smokers in Sweden has decreased over four decades to around 10%. The aim of the present study was to investigate the prevalence, distribution and associations of cardiovascular comorbidities in COPD by disease severity in two large areas of Sweden, both with low-smoking prevalence. Data from clinical examinations in 2009–2012, including spirometry and structured interview, from two large-scale population studies, the West Sweden Asthma Study (WSAS) and the OLIN Studies in Northern Sweden, were pooled. COPD was defined using post-bronchodilator spirometry according to the fixed ratio FEV1/FVC <0.70 and the lower limit of normal (LLN5th percentile) of the ratio of FEV1/FVC. Of the 1839 subjects included, 8.7% and 5.7% had COPD according to the fixed ratio and the LLN criterion. Medication for heart disease or hypertension among those with moderate-to-severe COPD was more common than among those without COPD (fixed ratio definition of COPD: 51% vs. 23%, p < 0.001; LLN definition: 42% vs. 24%, p = 0.002). After adjusting for known risk factors for COPD, including smoking, age, socio-economic status, and occupational exposure for gas, dust and fumes, only heart failure remained significantly, and independently, associated with COPD, irrespective of the definitions of COPD. Though a major decrease in smoking prevalence, the pattern of cardiovascular comorbidities in COPD still remains similar with previously performed studies in Sweden and in other Westernized countries as well.