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 FEV(1)/FVC<LLN in subjects reporting dyspnea or coughing, and moderate to severe COPD when FEV(1) <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.