30-year trends in asthma and the trends in relation to hospitalization and mortality

The present study examines how trends in the prevalence of asthma during the past three decades associate with hospitalization and mortality during the same period. Altogether 54 320 subjects aged 25–74 years were examined in seven independent cross-sectional population surveys repeated every five years between 1982 and 2012 in Finland. The study protocol included a standardized questionnaire on self-reported asthma, smoking habits and other risk factors, and clinical measurements at the study site. Data on hospitalizations were obtained from the Care Register for Health Care, and data on mortality from the National Causes of Death register. During the study, the prevalence of asthma increased - especially in women. In asthmatic compared with non-asthmatic subjects, hospitalization was significantly higher for all causes, respiratory causes, cardiovascular causes and lung cancer. In addition, particularly in asthmatic subjects, mean yearly hospital days in the 5-year periods after each survey diminished. In asthmatic subjects, the decrease in yearly all-cause hospital days was from 4.45 (between 1982 and 1987) to 1.11 (between 2012 and 2015) and in subjects without asthma the corresponding decrease was from 1.77 to 0.60 (p