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This Week in JAMA
May 17, 2006

This Week in JAMA

JAMA. 2006;295(19):2217. doi:10.1001/jama.295.19.2217
Hyperbaric Hypoxia Effects on Hemostasis

Venous thromboembolism has been associated with long-haul air travel, but whether this is due to the effects of prolonged sitting or other factors, such as reduced oxygen tension in the cabin, is not known. To assess the effects of hypoxia on markers of activated hemostasis during simulated long-haul air travel, Toff and colleaguesArticle conducted a single-blind, crossover study performed in a hypobaric chamber. Healthy study participants at low risk of thrombosis were seated for 8 hours in the chamber and exposed to hypobaric hypoxia or normobaric normoxia, equivalent to commercial air travel or atmospheric conditions at ground level, respectively. Blood samples were taken before and after chamber exposure to assess changes in markers of hemostasis. In analyses of pooled data from the study participants, the authors found no evidence of procoagulant changes that could be attributed to hypobaric hypoxia. In an editorial, BärtschArticle discusses the clinical implications of data from studies of hypoxia and inactivity and their effects on coagulation.

Effect of Policosanol on Lipid Levels

Policosanol, a substance derived from Cuban sugar cane, is advertised as a nonprescription lipid-lowering agent with effects comparable with statin therapy. To corroborate this claim and to test the effects in non-Hispanic patients, Berthold and colleagues conducted a clinical trial in white patients with hypercholesterolemia or combined hyperlipidemia who were randomly assigned to 10, 20, 40, or 80 mg/d of policosanol or placebo for 12 weeks. The authors found no evidence that policosanol—at usual or high doses—is more effective than placebo in reducing lipid levels.

Clinical Trial Outcomes and Funding Source

Data from the 1990s suggested that clinical trials funded by for-profit organizations were more likely to report positive findings than trials funded by not-for-profit organizations. To determine the effect of funding source on reports of positive outcomes in contemporary cardiovascular clinical trials, Ridker and Torres reviewed 324 consecutive therapeutic superiority trials published in 3 high-impact journals between 2000 and 2005. The authors found that trials funded by for-profit organizations or having funding from both for-profit and not-for-profit organizations were more likely to report positive findings than trials with not-for-profit funding sources.

Anti-TNF Antibody Therapy and Adverse Events

Tumor necrosis factor (TNF) is important in host defenses against infection and malignancy, and patients receiving anti-TNF therapy could be at increased risk of these adverse events. Bongartz and colleagues conducted a meta-analysis of data from placebo-controlled randomized clinical trials of anti-TNF antibody therapy in patients with rheumatoid arthritis to assess the risk of serious infections or malignancies in patients receiving anti-TNF therapy vs placebo. The authors found that patients with rheumatoid arthritis who were treated with anti-TNF antibody therapy had an increased risk of serious infection and a dose-dependent increased risk of malignancies.

Clinician's corner

Schievink discusses the epidemiology, etiology, diagnosis, and management of spontaneous intracranial hypotension, an underdiagnosed cause of new headache in young and middle-aged individuals.

A Piece of My Mind

“I . . . went on house calls. These were intended only for homebound patients, although sometimes our social worker would collar me into one of her regular visits, so she could show me living conditions that she considered particularly scandalous.” From: “Shut-ins.”

Medical News & Perspectives

The United States is falling behind other countries in publishing human embryonic stem cell research, but growing state and commercial efforts across the nation may help move the field forward.

Author in the Room Teleconference

Join William Taylor, MD, on Wednesday, May 31, 2006, from 2 to 3 PM eastern time to discuss approaches to screening for colon cancer. To register, go to http://www.ihi.org/AuthorintheRoom.

Audio Commentary

Dr DeAngelis summarizes and comments on this week's issue. Go to http://jama.ama-assn.org/misc/audiocommentary.dtl.

JAMA Patient Page

For your patients: Information about headaches.