Medical examiners use differing criteria to tally heat-related deaths
Tuesday, July 27, 2010
It's nature's stealth killer. It's not always the medical examiner's prime suspect. And the deadly toll it exacts often becomes clear only well after it has left the scene.
Stifling heat has already claimed 17 lives in Maryland this summer, as well as one in the District and nine in Virginia. Those numbers are likely to grow, experts said, because the hot weather's casualty figures are generally counted days and weeks after a heat wave ends.
High temperatures claim more lives in the United States than tornadoes, hurricanes, floods and lightning combined -- about 700 a year, according to official estimates.
Almost all are preventable. Better understanding can help prevent more deaths, some officials say, by encouraging people to take measures such as drinking fluids and seeking relief in an air-conditioned building, even if for just a few hours a day.
"People don't realize the severity of heat on health," said George Luber, an expert on heat at the Centers for Disease Control and Prevention. "It's the number one weather-related killer in the United States."
It will be a while before the summer's true tally is apparent, experts said. That's not just because more hot weeks are probably yet to come. Figuring out whether high temperatures played a role in a death is a complicated process. Different jurisdictions use different criteria, and what might be listed as a heat-related death in Maryland could be considered a heart attack in Virginia. The decision is ultimately a judgment call by doctors and medical examiners that may take weeks.
As a result, experts say, a heat wave's casualty figures are often underreported, and people bemoan the dog days of summer without realizing they can be fatal.
"The current numbers are likely underestimating the true magnitude of mortality," Luber said.
During heat waves, many more people than usual die of such illnesses as chronic respiratory ailments and heart disease, Luber said. Clear-cut cases of hyperthermia death are relatively rare, in part because the finding depends on hospital or emergency personnel measuring an elevated body temperature, usually 105 degrees or higher, at the time of death or immediately after.
There are "a lot of gray zones," said Randy Hanzlick, acting vice president of the National Association of Medical Examiners and chief medical examiner of Fulton County, Ga.
"If someone has really severe heart disease and it's really hot and they were working outside gardening, and they pass away, is that heat-related? That becomes a total judgment call," said Bart Ostro, chief of the air pollution epidemiology section at California's Environmental Protection Agency, who has studied heat-related mortality.
Officials have released few details about the people who died in the Washington area. Most in Maryland were seniors with underlying medical conditions who were found indoors with no air conditioning. The most recent death was of a Carroll County man who was mowing his lawn Friday. In Virginia, one death was an inmate at the Richmond jail; one was a roofer; and one was found indoors without air conditioning. The three most recent Virginia deaths occurred this past weekend in the central region, which includes Richmond. The District said only that its one victim died in early May.
Looking for clues
Leah Bush, Virginia's chief medical examiner, said each case is different.
"If we had a case where the doctor felt that heat contributed in enough of a way," the death would be considered heat-related, she said. But if heat played a minor role, that death might not be attributed to temperature, she said.
By contrast, in Maryland, which has reported the region's highest number of hot-weather-related fatalities this year, Chief Medical Examiner David R. Fowler said his office counts the death as heat-related "even if heat contributed 1 percent."
The District also counts deaths as heat-related if high temperatures are a contributing factor.
The CDC's most recent analysis of heat-related deaths in the United States, from 1999 to 2003, found that including deaths in which heat was a contributing factor increased the total number from 2,238 to 3,442, or 54 percent.
The experience of such cities as Philadelphia and Chicago during the mid-1990s brought widespread attention to the way heat deaths were defined. Until then, medical examiners typically relied on the classic definition of hyperthermia death, relying on elevated core body temperatures, officials said.
But in many suspected cases of hyperthermia death, people were alone, leaving no clue as to their body temperatures when they died. Medical examiners in the two cities began looking for other clues, such as whether windows were closed and the absence of fans or air conditioners.
As a result, during Philadelphia's heat wave in 1993, 118 residents were reported to have died of heat-related causes, while such nearby cities as New York, Washington and Baltimore, which used the old criteria, reported few such deaths or none.
During Chicago's heat wave in July 1995, the heat index topped 100 degrees for five days and surpassed 115 degrees on two consecutive days, according to official reports. The medical examiner's office reported more than 700 deaths.
The high death counts were controversial, but the CDC subsequently confirmed the findings.
Western Europe also has wrestled with the issue of how to calculate the death toll. After an eight-day heat wave in 2003, initial estimates put the number of heat-related deaths at 15,000 to 18,000, according to the CDC's Luber. More recent estimates put the total closer to 70,000, he said.
A particularly poignant tale comes from France, where families traditionally go on vacation in August. It was not unusual for it to go unnoticed when an elderly person -- especially one living on an upper floor of a building -- didn't appear for a day or two, said Ostro, of the California EPA. In many cases, those people succumbed to the heat.
Ultimately, figuring out whether heat played a role in someone's death is a process of exclusion, officials said. If someone is found dead at home, investigators will want to know whether that person had heart disease or might have fallen and suffered a head injury and a hemorrhage, said Bush, Virginia's chief medical examiner.
Maryland's Fowler likens the process to a "decision matrix."
"You rule things out and you rule things in," he said, "until eventually you get down to the point where I am comfortable saying with a reasonable degree of certainty that heat played a role."
Staff researcher Madonna Lebling contributed to this report.