Warmer nights may lead to ‘more cardiovascular deaths among men’

WARMER than usual summer nights appear to result in an increase in cardiovascular deaths in men in their early 60s, suggests new research.

According to the findings published in the online journal BMJ Open, a 1°C rise in summer night-time temperature may be linked to around four per cent higher risk of cardiovascular male deaths.

However, a similar correlation is not noticed in women.

Previous studies have focused on the potential for warm spells of weather during the summer that involve extreme or sustained periods of high temperatures to coincide with surges in deaths and hospitalisations due to cardiovascular conditions.

However, findings related to age and gender have been inconsistent so far.

Researchers from the University of Toronto examined a possible link between high temperatures on summer nights and increased cardiovascular disease (CVD) deaths amongst people aged 60-69 years.

They studied data from the Office for National Statistics on adult deaths attributed to CVD for June and July every year between 2001 and 2015 in England and Wales because heatwaves in the UK are most frequent and intense during these months.

They also gathered data for King County, Washington, a similarly sea-facing region. The US data, however, only included men.

Results showed that between 2001 and 2015, there were 39,912 CVD deaths (68.9 per cent men) recorded in England and Wales and 488 deaths in King County.

In England and Wales, a 1°C rise in the usual summer night-time temperature was associated with a 3.1 per cent increase in the risk of CVD mortality among men aged 60–64, but not older men or women of either age group.

In King County, a 1°C rise was associated with a 4.8 per cent increased risk of CVD mortality among those aged 65 and under, but not in older men, according to the study.

However, over the 15 years observed, CVD rates overall declined substantially in both regions annually and notably over the summer months, in line with greater population uptake of effective primary and secondary preventive therapies over time.

This is an observational study. The researchers acknowledge some limitations to their work such as the unavailability of 15-year sex- and age-specific weekly outcome and exposure data by district or city level.

The researchers said, “considering the growing likelihood of extreme summers in Western USA and UK, our results invite preventive population health initiatives and novel urban policies aimed at reducing future risk of CVD events.”