By Amy Norton
NEW YORK (Reuters Health) - Medical emergencies on commercial airplanes are not common, but certain passengers -- including the elderly and pregnant women -- face greater risks of complications requiring flight diversions, a study of one airline finds.
Researchers determined that over five years, one large Hong Kong-based airline logged 4,068 in-flight medical emergencies among paying passengers. That translated to a rate of about 12 emergencies per "billion revenue passenger kilometers" -- or the rate per paying passenger per billion kilometers traveled.
Medical emergencies requiring a flight diversion were much less common, at 46 over five years. Thirty passengers ultimately died, with heart attacks and other cardiac complications accounting for two-thirds of those deaths.
The findings, reported in a letter to the Archives of Internal Medicine, point to groups of passengers who seem to be at greatest risk of more serious health problems in the air.
Age was one of the key factors in the likelihood of emergencies leading to flight diversion or resulting in death, the study found. Passengers in their 70s and beyond had the highest risks -- not surprisingly, due to their higher rates of chronic diseases.
Pregnant women were also at risk, with obstetric complications having the highest rate of flight diversion -- at about 11 percent -- than any other type of medical emergency.
It is difficult to say whether these statistics would be similar for other major airlines, senior researcher Dr. Colin A. Graham, of the Chinese University of Hong Kong, told Reuters Health in an email.
He noted, though, that "we have no reason to expect that Hong Kong's airlines are substantially different from any other large airlines."
A recent study of two European airlines had similar findings as far as the number of medical emergencies, documenting just over 10,000 cases across both airlines over five years.
That study also tracked the rates of different types of emergencies, finding that syncope (loss of consciousness) accounted for just over half of the incidents. Gastrointestinal ills were the second-most common cause, at 9 percent, followed by heart problems, at 5 percent.
Overall, 3 percent of all emergencies required a flight diversion, with the most frequent causes of diversions being heart attacks, brain hemorrhages and epileptic seizures.
Those researchers concluded that while in-flight medical emergencies are "generally rare," they can have significant consequences -- for fellow passengers and flight crew as well.
According to Graham's team, it is not possible to change most of the risk factors for flight diversions and death seen in this study. However, the findings do underline the importance of having people with serious medical conditions get pre-flight medical clearance, the researchers say.
Other studies, they note, have suggested that two-thirds of in-flight emergencies are related to complications from pre-existing medical problems.
"Clearly," Graham said, "if potential passengers have any underlying health conditions, they should declare them to airline medical staff well in advance of flying to obtain pre-flight clearance to fly, and minimize the risk of an in-flight medical emergency."
He said that for people older than 70, "special care" should be taken to make sure that any medical conditions they have are stable before they take to the air.
According to Graham, people with existing health problems should talk with their own doctors, but it is best for pre-flight screening to be done by the airline's own medical team.
"We would recommend that passengers and their doctors consult the airlines' specialist aviation medicine teams at the earliest opportunity if the passenger has any significant underlying medical condition," he said.
Air travel usually presents no special risks to women with healthy pregnancies, but all pregnant women are generally advised to talk with their doctors before flying.
The second trimester is considered the safest travel window, as the chances of either miscarriage or spontaneous labor are lowest. Doctors often recommend against air travel after the 36th week of pregnancy, and many airlines have policies restricting travel in the third trimester.
SOURCE: http://link.reuters.com/deq36n Archives of Internal Medicine, August 9/23, 2010.