Is the Disease Burden from COPD in Norway Falling off? A Study of Time Trends in Three Different Data Sources.

Background: Less smoking should lead to fewer COPD cases. We aimed at estimating time trends in the prevalence and burden of COPD in Norway from 2001 to 2017.

Methods: We used pre-bronchodilator spirometry and other health data from persons aged 40-84 years in three surveys of the Tromsø Study, 2001-2002, 2007-2008 and 2015-2016. We applied spirometry lower limits of normal (LLN) according to Global Lung Initiative 2012. Age-standardized prevalence was determined. We defined COPD as FEV1 /FVC<LLN in subjects reporting dyspnea or coughing, and moderate to severe COPD when FEV1 <LLN was found in addition. We identified hospitalizations due to COPD exacerbations in the Norwegian Patient Registry 2010-2017, and retrieved the use of COPD medication from the Norwegian Prescription Database. Change in prevalence was analyzed by logistic regression.

Results: In the Tromsø Study, the age-standardized prevalence of daily smoking dropped from 29.9% to 14.1% among women and from 31.4% to 12.8% among men ( P <0.0001). The age-standardized prevalence of COPD dropped from 7.6% to 5.6% among women ( P =0.2) and from 7.3% to 5.6% among men ( P =0.003) and of moderate to severe COPD from 5.2% to 2.7% among women ( P =0.0003) and from 4.6% to 3.2% among men ( P =0.0008). Among men, the yearly age-standardized prevalence of hospitalization due to COPD exacerbation decreased from 3.6 to 3.0 per 1000 inhabitants aged 40-84 years ( P <0.0001). Correspondingly, dispensing oral corticosteroids or/and antibiotics for COPD exacerbations dropped from 6.6 to 5.8 per 1000 ( P <0.0001), while dispensing maintenance treatment increased ( P <0.0001).

Conclusion: COPD morbidity decreased between 2001 and 2017, which might partly be due to less smoking. The drop in smoking prevalence gives promise of a further substantial decrease in the coming decades.