Telling a first-person story about a health problem is a popular frame in medical writing, and it can be effective as long as the author adheres to the principles of high quality, evidence-based reporting.

An article on the front page of The Washington Post’s Health section in mid-January demonstrated how the personal narrative can go very wrong, however.

In the piece, John Donnelly—a former Boston Globe science reporter turned freelance writer and PR consultant—recounted how he developed potentially dangerous blood clots in his legs after taking a long-haul flight to the Philippines. The condition, called deep vein thrombosis (DVT), can occur after prolonged periods of immobility and can be life threatening if a clot breaks loose, travels in the bloodstream, and blocks an artery in the lungs, causing a pulmonary embolism (PE).

After experiencing shortness of breath and calf pain on runs in Manila and then back home in Washington, DC, Donnelly went to the hospital. What followed was a dramatic episode in which a technician, upon discovering the clots, exclaimed, “Oh, my god. Don’t move,” and fetched a doctor who, in turn, told Donnelly, “You’re lucky,” and prescribed two anticoagulants to prevent the clots from getting bigger and further clots from forming.

“So began my education on deep vein thrombosis,” Donnelly wrote in his testimonial for the Post. But the lessons he learned were incomplete.

Donnelly endured a terrifying ordeal that would have rattled anyone. DVT/PE is a serious condition, affecting 300,000 to 600,000 Americans every year, killing 60,000 to 100,000 of them, according to the Centers for Disease Control and Prevention. But Donnelly’s experience also led him to produce an article that badly mischaracterized the dangers of long-distance airplane travel. Here’s what he “found out”:

DVT is frequently called “economy-class syndrome” because of the number of people who get it after sitting immobilized in cramped seats on long flights.

I started hearing from friends, including many who work in global health, a subject I’ve been writing about for the past two decades. A friend who once worked at the World Health Organization said he once had DVT/PE after a long flight and now injected himself with an anti-clotting medicine 30 minutes before every long-distance trip; he said that enough people at WHO had DVT/PE from flights that it was almost an occupational hazard.

The science on DVT/PE directly contradicts both paragraphs. On Tuesday, the American College of Chest Physicians released the ninth edition of Antithrombotic Therapy and Prevention of Thrombosis, its guidelines for the prevention, diagnosis, and treatment of thrombosis. Researchers stated that there is no evidence to support “economy class syndrome” and advised long-distance travelers against the use of aspirin or anticoagulants to prevent DVT/PE.

For long-distance travelers at increased risk of DVT/PE (which includes people who’ve had it before, like Donnelly and his friend) the College of Chest Physicians suggested getting up and walking around frequently, exercising the calf muscles, sitting in an aisle seat (to facilitate mobility), and in some cases using graduated compression stockings, which help prevent blood from pooling and clotting in the legs during periods of immobility. But the guidelines advise against stockings for those who aren’t at increased risk. And they stress that antithrombotic drugs should be evaluated on an individual basis with the help of a physician, as some of them can cause severe bleeding and other life-threatening conditions.

“There has been a significant push in health care to administer DVT prevention for every patient, regardless of risk. As a result, many patients are receiving unnecessary therapies that provide little benefit and could have adverse effects,” said the chair of the guidelines panel, Gordon Guyatt, in a press release. “The decision to administer DVT prevention therapy should be based on the patients’ risk and the benefits of prevention or treatment.”

Donnelly’s implicit suggestion that even high-risk, long-distance travelers consider taking anti-clotting medicine, without adding a word of precaution, is therefore dangerous and irresponsible; his suggestion that there is such a thing as “economy class syndrome” is simply naïve and misleading.

The College of Chest Physicians stressed repeatedly in its guidelines that the chance of developing DVT/PE following long-distance air travel is very low. There is no definitive evidence suggesting that dehydration, alcohol intake, or sitting in economy class (as opposed to business or first class) increases a person’s risk. Sitting in a window seat does increase one’s risk, but only because it impedes mobility.

Curtis Brainard is the editor of The Observatory, CJR's online critique of science and environment reporting. Follow him on Twitter @cbrainard.