CHICAGO—Women who are given intravenous magnesium sulfate just before the birth of a very preterm baby may reduce the infant's risk of neurosensory impairments such as cerebral palsy, though this finding needs to be confirmed in other studies before it becomes standard practice, according to an article in the November 26 issue of The Journal of the American Medical Association (JAMA).

Infants born very preterm have increased risks of death or neurosensory impairments and disabilities such as cerebral palsy, according to background information in the article. Although other studies have suggested that use of prenatal magnesium sulfate may act as a neuroprotective agent for very preterm infants, there have been no large randomized controlled trials in which magnesium sulfate was given solely for neuroprotection.

Caroline A. Crowther, M.D., of The University of Adelaide, South Australia, and colleagues conducted a study to determine the effectiveness of magnesium sulfate in preventing pediatric death and/or cerebral palsy when given to women at risk of delivery before 30 weeks' gestation.

The study was a randomized controlled trial at 16 hospitals in Australia and New Zealand. It included 1,062 women with fetuses younger than 30 weeks' gestation for whom delivery was planned or expected within 24 hours. The participants were enrolled from February 1996 to September 2000 with follow-up of surviving children at 2 years of age. Women were randomly assigned to receive an intravenous infusion of magnesium sulfate solution or sodium chloride solution (as placebo) for 20 minutes followed by a maintenance infusion for up to 24 hours.

Data were analyzed for 1,047 (99 percent) 2-year survivors. "Total pediatric mortality (13.8 percent vs. 17.1 percent; [17 percent reduced risk]), cerebral palsy in survivors (6.8 percent vs. 8.2 percent; [17 percent reduced risk]), and combined death or cerebral palsy (19.8 percent vs. 24.0 percent; [17 percent reduced risk]) were less frequent for infants exposed to magnesium sulfate, but none of the differences were statistically significant. Substantial gross motor dysfunction (3.4 percent vs. 6.6 percent; [49 percent reduced risk]) and combined death or substantial gross motor dysfunction (17.0 percent vs. 22.7 percent; [25 percent reduced risk]) were significantly reduced in the magnesium group," the researchers write.

CHICAGO—The blood thinner warfarin can be safely and effectively used to prevent stroke in patients with atrial fibrillation, according to an article in the November 26 issue of The Journal of the American Medical Association (JAMA).

According to background information in the article, multiple randomized clinical trials have demonstrated warfarin therapy to be highly effective in reducing the risk of ischemic stroke in patients with atrial fibrillation (an electrical rhythm disturbance of the heart that causes an irregular heartbeat). In these trials, treatment was associated with relatively low rates of bleeding, which is the major possible adverse effect of warfarin treatment. However, concerns persist about the effectiveness and safety of warfarin in persons treated in usual clinical care since the randomized trials enrolled highly selected patients, included few very elderly patients, and closely monitored patients' level of anticoagulation. This has important clinical implications since atrial fibrillation occurs commonly, particularly among the elderly.

Alan S. Go, M.D., of Kaiser Permanente of Northern California, Oakland, Calif., and colleagues evaluated the effect of warfarin on risk of thromboembolism (the blocking of a blood vessel, e.g., in the brain, by a blood clot), hemorrhage, and death in patients with atrial fibrillation within a usual care setting. The study was conducted between July 1, 1996, and December 31, 1997, with follow-up through August 31, 1999, in a large integrated health care system in Northern California. Of 13,559 adults with atrial fibrillation (not due to a problem with a heart valve), 11,526 were studied, 43 percent of whom were women. The average age was 71 years.

Among 11,526 patients, 397 thromboembolic events (372 ischemic strokes) occurred, and warfarin therapy was associated with a 51 percent lower risk of thromboembolism and stroke compared with no warfarin therapy (either no antithrombotic therapy or aspirin) after adjusting for potential confounders and likelihood of receiving warfarin.

"Warfarin was effective in reducing thromboembolic risk in the presence or absence of risk factors for stroke," the authors write. An "analysis estimated a 64 percent reduction in odds of thromboembolism with warfarin compared with no antithrombotic therapy. Warfarin was also associated with a reduced risk of all-cause mortality [death, 31 percent lower risk]. Intracranial hemorrhage [bleeding into the brain] was uncommon, but the rate was moderately higher among those taking vs. not taking warfarin. However, warfarin therapy was not associated with an increased adjusted risk of nonintracranial major hemorrhage."

"Our results materially extend … prior findings by providing contemporary and precise estimates of thromboembolism and hemorrhage rates in a broad population of individuals with atrial fibrillation, along with more complete adjustment for potential confounders and attempts to control for the likelihood of receiving warfarin over time," they write.

CHICAGO—Limiting certain high-risk surgery procedures to hospitals that perform high numbers of these operations could be implemented without making patients travel much farther, according to a new study in the November 26 issue of The Journal of the American Medical Association (JAMA).

"For many surgical procedures, operative mortality [death] rates are substantially lower at hospitals that perform them more frequently," the authors write in background information. "As a result, concentrating selected procedures in higher-volume hospitals is advocated by many. … Previous analyses suggest that such regionalization policies could avert hundreds, if not thousands, of surgical deaths each year in the United States."

However, many worry that such policies would imply unreasonable travel burdens if patients, especially those in rural areas, were required to travel to higher-volume centers for surgery.

John D. Birkmeyer, M.D., of Dartmouth-Hitchcock Medical Center, Lebanon, N.H., and colleagues used national Medicare claims data and U.S. road network information to assess the travel time implications of setting minimum volume standards for two surgical procedures - pancreatic resection (removal or all or part of the pancreas) and esophagectomy (partial or total removal of the esophagus). Data were analyzed from 15,796 Medicare patients undergoing these two procedures between 1994 and 1999. These procedures were chosen for this study because they are usually scheduled electively and are performed infrequently enough that regionalization (limiting these procedures to certain hospitals) would not affect large numbers of patients, according to the authors. Also, the authors note that surgical death rates with each procedure were 12 percent higher at very low-volume hospitals than at very high-volume centers (16 percent vs. 4 percent for pancreatic resection, 20 percent vs. 8 percent for esophagectomy).

"With low-volume standards (1/year for pancreatectomy; 2/year for esophagectomy), approximately 15 percent of patients would change to higher-volume centers, with negligible effect on their travel times," the authors found. "Most patients would need to travel less than 30 additional minutes (74 percent pancreatectomy; 76 percent esophagectomy). Many patients (about 25 percent) already lived closer to a higher-volume hospital (25 percent pancreatectomy; 26 percent esophagectomy). Conversely, with very high-volume standards (more than 16/year for pancreatectomy; more than 19/year for esophagectomy), approximately 80 percent of patients would change to higher-volume centers. More than 50 percent of these patients would increase their travel time by more than 60 minutes. Travel times would increase most for patients living in rural areas."

BLOOD THINNER WARFARIN SHOWN TO BE EFFECTIVE IN 'REAL WORLD' SETTING/PATIENTS