Warmer nights may result in an increase in cardiovascular mortality in men

Warmer Nights May Lead To More Cardiovascular Deaths Among Men

Researchers say that men who are in their early 60s may die from heart disease because of hotter than normal summer evenings, but not women. This is according to a study in the online journal BMJ Open.

Previous research has focused on the possibility of summer warm spells involving extreme or sustained high temperatures to correspond with increases in mortality and hospitalizations due to cardiovascular diseases.

Researchers from the University of Toronto in Canada set out to investigate any possible link between summer high temperatures at night and increased cardiovascular disease (CVD) fatalities among people aged 60 to 69 years.

A heatwave is more common and intense in June and July, so they looked at Office for National Statistics data on adult deaths in England and Wales that were caused by cardiovascular disease from 2001 to 2015. This is because heatwaves are more common and intense in these two months.

They also acquired data for King County, Washington, a similarly sea-facing region at a similar latitude to England and Wales, with similar land-ocean atmospheric characteristics and a low prevalence of household air conditioning. The data from the United States, on the other hand, only included men.

They also looked at official meteorological data from the United Kingdom and the United States.

According to the findings, there were 39,912 CVD fatalities in England and Wales (68.9% men) between 2001 and 2015, including 488 deaths in King County.

After controlling for other variables, a 1°C increase in average summer night-time temperature was associated with a 3.1 percent increase in the risk of CVD mortality among men aged 60–64 in England and Wales, but not older men or either of the women’s age groups.

In King County, a 1°C increase was associated with a 4.8 percent increased risk of CVD death among those aged 65 and younger, but not in older men.

Over the 15 years of the study, the rates of cardiovascular disease in both regions dropped significantly each year, especially in the summer. This shows that more people are willing to use effective primary and secondary prevention methods.

Nonetheless, the authors found that there was a significant residual risk, with incident rates in England and Wales being more than 50% higher in people aged 65–69 than in those aged 60–64.

This was concerning, they added, because in recent years, populous places like the ones investigated have shown a proportionate growth in summer heat intensity at night rather than during the day.

In an observational study, the researchers say there are some things they could have done better. For example, they didn’t have 15-year weekly sex and age-specific weekly outcome and exposure data by district or city level, which could have found stronger associations between night-time summer heat and CVD mortality in densely populated urban areas.

Even so, the study’s huge population size data and the use of reliable national mortality and meteorological data were both good things about it.

“The findings should prompt similar studies of exposure and incident rates in other popular mid-latitude to high-latitude areas,” they said.

Given the rise in harsh summers in the Western United States and the UK, our findings call for public health programs and creative urban strategies to help prevent future cardiovascular disease (CVD).