Mortality and its predictive factors in participants with asthma: a 26-year follow-up

The long-term impact of asthma on mortality remains uncertain. This study aimed to assess mortality and its predictors over 26 years in asthmatic participants compared to those with or without other respiratory symptoms.

This longitudinal cohort study included participants recruited from the general Swedish population, followed from 1990 to 2016. The younger (30-39 years, n = 938) and older (60-69 years, at baseline, n = 1020) groups were divided into asthma, other and no respiratory symptoms. Baseline data included spirometry, allergy testing, smoking status, and quality of life. Survival analyses were conducted using Kaplan-Meier and Cox proportional hazards models.

At 26-years follow-up the survival rates were 34 % and 95 % for asthmatics in the older and younger age groups, respectively. Asthma was not found to be a statistically significant independent predictor of mortality when compared to non-asthmatics in either age group (older group HR 95 % CI: 0.94 (0.77-1.15); younger group: 1.39 (0.63-3.09). Significant mortality predictors included increasing age ((1.13 (1.10-1.16)), male sex (1.73 (1.44-2.07), smoking (2.01 (1.65-2.44), lower forced expiratory volume in 1 s (FEV₁) (0.67 (0.60-0.76), and more symptoms (1.21 (1.01-1.45) in the older group, while age (1.14 (1.02-1.27) and other respiratory symptoms (2.44 (1.18-5.03) were predictors in the younger group. Risk factors significantly linked to mortality among older asthmatics included older age, male sex and current passive smoking, and only male sex in younger asthmatics.

Asthma was not a strong independent predictor of mortality in either age group, whereas age, male sex, other respiratory symptoms, smoking, and lower FEV_1, but not quality of life, were key risk factors. These findings highlight the importance of identifying high-risk individuals and addressing modifiable lifestyle factors such as smoking in mortality prevention strategies.