Demographic, lifestyle and comorbid risk factors for all-cause mortality in a Danish cohort of middle-aged adults with incident asthma

Objective We aimed to identify factors associated with all-cause mortality in adults with incident asthma.Design and setting Cross-sectional cohort study, in the metropolitan areas of Copenhagen and Aarhus, Denmark.Participants Adults aged 50–64 years enrolled in the Danish Diet, Cancer, and Health cohort were followed up from baseline (1993–1997) in the National Patients Registry for first-time admissions for asthma and vital status. We defined incident asthma as at least one first-time hospital admission with asthma as the primary registered diagnosis between baseline and end of follow-up (2013) in participants without previously known asthma. Among the cohort comprising 57 053 individuals, we identified 785 adults (aged 50—64) with incident asthma, of whom 76 died during follow-up.Primary and secondary outcome measures Baseline reported socioeconomic and lifestyle traits, and comorbidities associated with all-cause mortality.Results Self-reported leisure-time physical activity was associated with a substantial reduction in risk with an HR of 0.53 (95% CI 0.33 to 0.85). Being male, single and having a diagnosis of hypertension or diabetes were associated with an increased risk of all-cause mortality with an HR of 1.83 (95% CI 1.14 to 2.38), 2.16 (95% CI 2.06 to 4.40), 2.47 (95% CI 1.54 to 3.95) and of 2.42 (95% CI 0.96 to 6.11), respectively.Conclusions This long-term study of adults with hospital contacts for incident asthma revealed that self-reported leisure-time physical activity is associated with an approximately 50% reduction in all-cause mortality. In contrast, both hypertension and diabetes were associated with a higher risk of mortality.