A prospective cohort study of bedroom warming with a heating system and its association with common infectious diseases in children during winter in Japan

BACKGROUND: Customarily, bedrooms in Japan are left unheated. Although several studies have reported that the use of a heating system has positive outcomes on respiratory infection and asthma, the preventive effect of heating systems against infectious diseases in children is not well known. METHODS: We conducted a cohort study using two questionnaire surveys, one before the winter season in November, 2018 and the second after winter in March, 2019.Participants were 155 children who did not use a heating system in the bedroom and 156 children who did. RESULTS: Having a heated bedroom with a heating system was associated with decreased odds for the frequency of cold (>/=3 times) (adjust odds ratio (AOR): 0.35, 95% confidence interval (CI): 0.19-0.65), duration of fever (>/=3 days) (AOR: 0.38, 95% CI: 0.22- 0.66), duration of medicine for a cold (>/=3 days) (AOR: 0.91, 95% CI: 0.87-0.95), hospital visit due to cold (>/=3 days) (AOR: 0.54, 95% CI: 0.31-0.94), absence from school or nursery (>/=3 days) (AOR: 0.43, 95% CI: 0.27-0.70), influenza infection (AOR: 0.43, 95% CI: 0.26-0.71) and gastroenteritis (AOR: 0.39, 95% CI: 0.21-0.72). Influenza vaccination reduced the odds of influenza infection (AOR: 0.36, 95% CI: 0.22-0.59) and absence from school or nursery (>/=3days<=) (AOR: 0.62, 95% CI: 0.39-0.99). CONCLUSION: This study implies that the heating of bedrooms may have a preventive effect against infections among children. Broader dissemination of this knowledge in Japan will require cultural change through public health awareness.