A 20-Year Follow-Up of a Population Study-Based COPD Cohort-Report from the Obstructive Lung Disease in Northern Sweden Studies

Abstract

Mortality and other long-term outcomes of COPD from epidemiological studies of cohorts based on the general population are still rare. In contrast, data from follow-ups of patients from hospitals and general practices are more common and demonstrate often a 5-year mortality of about 50% and even higher. The aim was to study 20-year outcomes, mainly mortality, in a COPD cohort derived from a population study. The Obstructive Lung Disease in Northern Sweden (OLIN) Study's first postal survey was performed in 1985, and 5698 subjects (86%) responded. A stratified sample of symptomatic subjects and controls was invited to clinical examinations including lung function tests in 1986, 1506 (91%) of the invited participated and 266 subjects fulfilled the GOLD criteria of COPD. All alive and possible to trace had participated at least at two follow-up examinations. Of the 266 subjects with COPD 46% were still alive after 20 years. The proportion of survived among subjects with severe and very severe COPD at entry was 19%. Death was significantly related to age, male sex, disease severity and concomitant ischemic heart disease or cardiac failure at entry. Socioeconomic status (manual workers) was significant in the univariate analysis, but failed to reach statistical significance in the multivariate model. The annual decline in FEV₁ among survivors was low to normal. Long-term follow-ups of subjects with COPD derived from population studies provide data reflecting the course of COPD in society better than follow-ups of hospital recruited patients, who represent the top of the iceberg. Surprisingly many with severe COPD were still alive after 20 years.

Keywords:

• COPD
• mortality
• epidemiology
• prospective population study