In a significant finding, an analysis spanning nearly four decades has revealed that young men living in the US are overall more likely to die in the summer months. Published in eLife, the study used data on 85,854,176 deaths in the US between 1980 and 2016 from the vital registration and found that men and women aged 45 years and older remain more likely to die in winter, regardless of the regional climate.
The data was analysed using a technique called wavelet analysis, where death rates are studied through a kind of “moving window” over time, revealing changes. “It is well established that death rates vary throughout the year, but there is limited information on how this seasonality varies by local climate and how it has changed over time for different diseases and at different ages,” explained lead author Robbie Parks, PhD student at Imperial College London, UK.
“In this study, we set out to comprehensively characterise the patterns of death over different time periods and geographical areas to understand when and where death rates are at their highest and lowest,” added Parks who is with the MRC-PHE Centre for Environment and Health.
The research team found that deaths from overall mortality (any cause of death) in men aged 45 years and older and women aged 35 years and older peaked in December, January or February, and were lowest in June to August. “Deaths from heart and lung diseases were highest in January and February and lowest in July and August regardless of age,” the team said.
Deaths in children younger than five were highest in February and lowest in August. By contrast, deaths from overall mortality peaked in June and July for males aged between five and 34 years old Deaths from injuries were highest in the summer for both men and women younger than 45 years old Over the 37 years, the per-cent differences in seasonal death rates changed little for people aged 45 and older.
“But there was a marked decline in the per-cent difference between summer and winter deaths in younger people of both sexes, especially in boys,” the study noted. “We have identified distinct seasonal patterns relating to age, sex and disease, including higher summer deaths in young men,” said senior author Majid Ezzati, Professor of Global Environmental Health at Imperial College London.
“The persistent peak in winter deaths observed in older people demonstrates the need for environmental and health service interventions targeted towards this group, irrespective of geography and local climate,” Ezzati added.