52-year follow-up of a birth cohort reveals a high pneumonia incidence among young men.

Background: Knowledge of pneumonia incidence and risk factors in adults is mainly based on clinical studies of selected patient data and registers with ageing populations. Prospective population-based investigations, such as birth cohort studies, are needed to understand pneumonia incidence and risk factors among young and working-age populations.

Methods: Northern Finland Birth Cohort (NFBC) 1966 data (n=6750) were analysed for pneumonia incidence and risk factors. Incidence analysis was replicated using data from an independent NFBC 1986 cohort (n=9207). Pneumonia in relation to chronic conditions and lifestyle factors was analysed.

Results: A peak with a maximum of 227 pneumonia episodes per 10 000 among men between the ages of 19 and 21 years was found in two independent cohorts. Pneumonia was associated with male sex (relative risk 1.72, 95% CI 1.45-2.04; p<0.001), low educational level (relative risk 2.30, 95% CI 1.72-3.09; p<0.001), smoking (relative risk 1.55, 95% CI 1.31-1.84; p<0.001), asthma (relative risk 2.19, 95% CI 1.73-2.75; p<0.001), cardiovascular diseases (relative risk 2.50, 95% CI 2.04-3.07; p=0.001), kidney diseases (relative risk 4.14, 95% CI 2.81-6.10; p<0.001), rheumatoid arthritis (relative risk 2.69, 95% CI 1.80-4.01; p<0.001), psoriasis (relative risk 2.91, 95% CI 1.92-4.41; p<0.001) and type II diabetes (relative risk 1.80, 95% CI 1.34-2.42; p<0.001). Men with excessive alcohol consumption at age 31 years were at risk of future pneumonia (relative risk 2.40, 95% CI 1.58-3.64; p<0.001).

Conclusions: Birth cohort data can reveal novel high-risk subpopulations, such as young males. Our study provides understanding of pneumonia incidence and risk factors among young and working age populations.