Abstract
BackgroundCOPD has increased in prevalence worldwide over several decades until the first decade after the millennium shift. Evidence from a few recent population studies indicate that the prevalence may be levelling or even decreasing in some areas in Europe. Since the 1970s, a substantial and ongoing decrease in smoking prevalence has been observed in several European countries including Sweden. The aim of the current study was to estimate the prevalence, characteristics and risk factors for COPD in the Swedish general population. A further aim was to estimate the prevalence trend of COPD in Northern Sweden from 1994 to 2009.MethodsTwo large random population samples were invited to spirometry with bronchodilator testing and structured interviews in 2009–2012, one in south-western and one in northern Sweden, n = 1839 participants in total. The results from northern Sweden were compared to a study performed 15 years earlier in the same area and age-span. The diagnosis of COPD required both chronic airway obstruction (CAO) and the presence of respiratory symptoms, in line with the GOLD documents since 2017. CAO was defined as post-bronchodilator FEV1/FVC < 0.70, with sensitivity analyses based on the FEV1/FVC < lower limit of normal (LLN) criterion.ResultsBased on the fixed ratio definition, the prevalence of COPD was 7.0% (men 8.3%; women 5.8%) in 2009–2012. The prevalence of moderate to severe (GOLD ≥ 2) COPD was 3.5%. The LLN based results were about 30% lower. Smoking, occupational exposures, and older age were risk factors for COPD, whereof smoking was the most dominating risk factor. In northern Sweden the prevalence of COPD, particularly moderate to severe COPD, decreased significantly from 1994 to 2009, and the decrease followed a decrease in smoking.ConclusionsThe prevalence of COPD has decreased in Sweden, and the prevalence of moderate to severe COPD was particularly low. The decrease follows a major decrease in smoking prevalence over several decades, but smoking remained the dominating risk factor for COPD.
Highlights
Chronic obstructive pulmonary disease (COPD) has increased in prevalence worldwide over several decades until the first decade after the mil‐ lennium shift
Adjusted for age and sex by Poisson regression, the prevalence decreased by 44% (PR 0.56, 95% Confidence Intervals (CI) 0.38–0.83)
Among subjects with COPD in 1994 compared to 2009, the mean age was 54.1y compared to 59.5y (P = 0.025), the proportion of never-smokers 18.0% compared to 14.7% (P = 0.678), and the proportion with any physician-diagnosed obstructive airway disease was 14.8% compared to 29.4% (P = 0.087)
Summary
COPD has increased in prevalence worldwide over several decades until the first decade after the mil‐ lennium shift. Since the 1970s, a substantial and ongoing decrease in smoking prevalence has been observed in several European countries including Sweden. The aim of the current study was to estimate the prevalence, characteristics and risk factors for COPD in the Swedish general population. The prevalence of COPD has increased during the past century with tobacco smoking being the most important risk factor especially in high income countries [1]. Since the 1970s, a substantial and ongoing decrease in smoking prevalence has been observed in North America, Australia, and in several northern and western European countries [6], at least partly due to different public health interventions. Some recent studies based on spirometry have indicated the prevalence trend of COPD to be levelling off or even tending to decrease [7,8,9,10]. The substantial reduction in smoking will probably contribute to a reduced future burden of COPD
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