By DR. AMAR NARULA, ABC News Medical Unit
After the warmest March on record, people are already talking about whether a scorching summer lies ahead.
It turns out that even small changes in summer temperature may pose a health risk to older adults with chronic medical conditions, according to a study published today in the Proceedings of the National Academy of Sciences.
Summers in which temperatures were more of a roller coaster ride posed a greater hazard for people who had recently been hospitalized for a variety of illnesses, than those summers with steadier temperatures.
The study looked at patients over the age of 65 who lived in one of 135 US cities for over 20 years, and who had recently been hospitalized for heart attacks, chronic obstructive pulmonary disease, congestive heart failure, or diabetes.
Researchers found that for each extra Celsius degree in temperature swings, older people with these conditions experienced a 2.8 to 4 percent increased risk of dying, depending on their condition. Based on these increases in rates, they estimate temperature variability could account for thousands of additional deaths per year.
"People adapt to the usual temperature in their city," says Joel Schwartz, professor of environmental epidemiology at the Harvard School of Public Health and senior author of the study. "That is why we don't expect higher mortality rates in Miami than in Minneapolis, despite the higher temperatures. But people do not adapt as well to increased fluctuations around the usual temperature."
"This 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 this public health problem is likely to grow in importance in the future," Schwartz said.
The study notes that death rates and temperature swings were dampened in cities with more green space. Could trees help prevent deaths going forward?
Another potential intervention could include warning systems to be put in place when temperatures change by a certain amount.
"These findings are the first to demonstrate health risks related to temperature variability," says Patrick Kinney, director of the Columbia University Climate and Health Program.
The study looked at temperature changes independent of heat waves and ozone levels, which are also linked to an increased risk of death in the elderly. Future work will focus on why the elderly do not adapt as well to heat, and whether changes in heart rate and blood pressure may be driving the increased risk.