Large underreporting of COPD as cause of death-results from a population-based cohort study

Abstract

Background: In 2019, WHO estimated COPD to be the third leading cause of death in the world. However, COPD is probably underestimated as cause of death due to the well-known under-diagnosis.

Aim: To evaluate the proportion of and factors associated with COPD recorded as cause of death in a long-term follow-up of a population-based COPD cohort.

Methods: The study population includes all individuals (n = 551) with COPD defined as chronic airway obstruction (post-bronchodilator FEV₁/FVC<0.70) + respiratory symptoms identified after re-examinations of four population-based cohorts. Mortality and underlying or contributing cause of death following ICD-10 classification were collected from the Swedish National Board of Health and Welfares register from date of examination in 2002-04 until 2016.

Results: The study sample consisted of 32.3% GOLD 1, 55.9% GOLD 2, and 11.8% GOLD 3-4. The mean follow-up time was 10.3 (SD3.77) years and the cumulative mortality 45.0%. COPD (ICD-10 J43-J44) was recorded on 28.2% (n = 70) of the death certificates (11.1%, 25.7% and 57.1% by GOLD stage), whereof n = 35 had COPD recorded as underlying and n = 35 as contributing cause of death. To have COPD recorded as cause of death was independently associated with ex- and current smoking and a self-reported physician diagnosis of COPD, while male sex, overweight/obesity and higher FEV₁% of predicted associated with the absence.

Conclusions: COPD was largely underreported cause of death. Even among those with severe/very severe disease, COPD was only mentioned on 57.1% of the death certificates.

Keywords: Chronic obstructive pulmonary disease; Epidemiology; Mortality; Physician diagnosis; Risk factor.