May 22, 2012 (San Diego, California) — Flying or traveling to high-altitude locations seems to increase the risk for flares in people with inflammatory bowel disease (IBD), researchers reported here at Digestive Disease Week 2012.
"Our most striking finding was a statistically significant correlation between the occurrence of flares and a journey to a high altitude, particularly in Crohn's disease, but also in ulcerative colitis," said lead author Stephan R. Vavricka, MD, from Triemli Hospital in Zurich, Switzerland.
There is increasing experimental evidence suggesting that hypoxia induces inflammation in the gastrointestinal tract. Hypoxia-inducible transcription factor-1α influences adaptive immunity and has been shown to induce barrier-protective genes in the case of experimentally induced colitis, Dr. Vavricka explained.
"But the clinical impact of hypoxia in patients with IBD is, so far, poorly investigated," said Dr. Vavricka, who said the idea for this study was triggered by first-hand reports from skiers and mountaineers with IBD who complained of flares within a week of being at higher elevations.
"We wanted to evaluate whether flights and journeys to regions 2000 meters or more above sea level [6562 feet] are associated with the occurrence of flares in IBD patients in the subsequent 4 weeks," he said.
Dr. Vavricka and colleagues asked 103 patients seen at 3 tertiary referral IBD clinics to complete questionnaires regarding their travel and habits 4 weeks preceding flares. Patients with flares were matched with an IBD group in remission during the observation period (according to age, sex, smoking habits, and medication).
In the group, 43 patients had Crohn's disease and 60 had ulcerative colitis. Fifty-two patients with flares were matched to 51 patients without flares.
Overall, IBD patients with flares reported significantly more flight and/or journeys to regions 2000 meters or more above sea level than patients in remission (40.4% vs 15.7%; P = .005), Dr. Vavricka said.
For Crohn's disease, a statistically significant correlation was shown between flares and high-altitude journeys in patients with flares, compared with those in remission (38.1% vs 9.1%; P = .024). For ulcerative colitis, there was a trend toward more frequent flights and high-altitude journeys in patients with flares (41.9% vs 20.7%; P = .077). Mean flight duration was approximately 6 hours.
The groups were controlled for age, smoking, physical activity, antibiotic treatment, intake of nonsteroidal anti-inflammatory drugs, frequency of chronic obstructive pulmonary disease, and oxygen therapy.
"We have concluded that flights and stays at high altitudes are a risk factor for IBD flares," Dr. Vavricka said. "At this point, it's too early to tell patients not to go to high altitudes or to abstain from flying; this is a small retrospective study. However, mice exposed to hypoxia show inflammation in the intestine, and mountaineers at high altitudes have been shown to have an inflammatory state that can be measured in the blood and intestine. Based on these studies, it's probably worth examining on a molecular level whether hypoxia does induce intestinal inflammation in persons with IBD," he noted.
Jerrold R. Turner, MD, PhD, the Sara and Harold Lincoln Thompson Professor at the University of Chicago in Illinois, who moderated a press briefing where Dr. Vavricka spoke, said the findings are consistent with what is known from animal models, and although it is a small study, "there is no reason to think the data are wrong."
It is premature to suggest that people with IBD avoid high altitudes, he said, but "with complicated patients — for example, a woman who has finally gotten pregnant — you might suggest they skip that mountain vacation for now."
Dr. Vavricka said that 2 of his patients who are ski instructors have learned, without consultation with him, that they can prevent flares at high altitudes by taking a small dose of prednisone the week prior. While not a recommendation for treatment, Dr. Turner said this is "anecdotally interesting."
Dr. Vavricka and Dr. Turner have disclosed no relevant financial relationships.
Digestive Disease Week (DDW) 2012: Abstract 303. Presented May 20, 2012.
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