Background: Little is known on associations between respiratory symptoms and mortality.

Aim: To study whether respiratory symptoms are risk factors for all-cause, respiratory, cardiovascular (CV), and cancer mortality in Sweden and Norway.

Methods: In 1995-1997, population samples (20-69y) were surveyed about respiratory symptoms, and n=7,104 (85.3% of invited, median age 45y) and n=54,240 (70.1%, 44y) participated within the OLIN Studies in Northern Sweden and the HUNT Study in Norway. Mortality was studied until December 31st 2015. Hazard ratios (HR) for associations between respiratory symptoms and mortality were estimated by Cox regression models adjusted for age, sex, educational level, and smoking habits.

Results: The cumulative 20-year mortality was 14.5% in OLIN and 12.6% in HUNT. Dyspnea (mMRC grade≥2) (HR 1.9, 95%CI 1.6-2.2 in OLIN and 1.6, 1.5-1.7 in HUNT), chronic productive cough (1.5, 1.3-1.8 and 1.5, 1.3-1.6), and wheeze (1.3, 1.1-1.5 and 1.3, 1.2-1.4) were associated with increased risk of all-cause mortality. Women reported dyspnea and wheeze more frequently than men in both countries, but the association with mortality was similar in both sexes. Causes of death were studied in OLIN, where dyspnea associated with increased risk of respiratory (3.6, 2.1-6.1), CV (2.1, 1.6-2.7), and cancer (1.3, 1.0-1.8) mortality. Chronic productive cough was associated with increased risk of respiratory (2.4, 1.3-4.3) and cancer (1.6, 1.2-2.2) mortality, while wheeze was associated with increased risk of respiratory (3.5, 2.1-5.7) and CV (1.3, 1.0-1.6) mortality.

Conclusions: Common respiratory symptoms were similarly associated with increased risk of mortality in adults in Sweden and Norway.