Summer weather changes threaten health of elderly
MedWire News: Elderly people with chronic illnesses are at increased risk for death following exposure to unusual temperature increases over the summer, say researchers.
"The effect of temperature patterns on long-term mortality has not been clear to this point," explained lead study author Antonella Zanobetti (Harvard School of Public Health, Boston, USA) in a press statement.
"We found that, independent of heat waves, high day-to-day variability in summer temperatures shortens life expectancy. This variability can be harmful for susceptible people."
As reported in the Proceedings of the National Academy of Sciences of the USA, Zanobetti and colleagues used Medicare data from 1985 to 2006 for four cohorts of people across 135 cities to assess whether seasonal temperature changes influence mortality.
The cohort members were all aged over 65 years and were hospitalized with chronic obstructive pulmonary disease (COPD; n=3,749,096), diabetes (n=3,364,868), congestive heart failure (CHF; n=1,939,149), or myocardial infarction (MI; n=1,454,928).
Over the period analyzed, 60.9% of the CHF, 41.9% of the MI, 43.0% of the diabetes, and 49.8% of the COPD cohort died.
The team found that, on average, each 1°C increase in summer temperature above the average for the time of year increased the death rate of those in the four cohorts. Specifically, the mortality risk increased by 4.0% in those in the diabetes cohort, and by 3.8%, 3.7%, and 2.8% in those in the MI, COPD, and CHF cohorts, respectively.
African-Americans and those living in poverty had a 1-2% greater mortality risk than people from other ethnicities or who had greater financial resources. Mortality was also greater in hotter cities. By contrast, above-average amounts of green space in a city was associated with a 1-2% reduction in mortality.
The researchers believe that the observed mortality increases could result in over 10,000 additional deaths as a result of temperature fluctuation every year. p>"People adapt to the usual temperature in their city. That is why we don't expect higher mortality rates in Miami than in Minneapolis, despite the higher temperatures," commented study co-author Joel Schwarz, also from Harvard School of Public Health, to the press.
"But people do not adapt as well to increased fluctuations around the usual temperature," he added.
"That finding, combined with the increasing age of the population, the increasing prevalence of chronic conditions such as diabetes, and possible increases in temperature fluctuations due to climate change, means that this public health problem is likely to grow in importance in the future."
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By Helen Albert