Clinical Briefs: EBV Antibodies and Risk of MS; cANG for Detection of Coronary Stenosis; Vitamin A and Hip Fractures
February 28, 2002 3 minutes read
EBV Antibodies and Risk of MS
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Current theories dominantly support an autoimmune etiologic basis for multiple sclerosis (MS). An epidemiologic phenomenon peculiar to Epstein-Barr virus (EBV) is its pattern of asymptomatic infection in childhood, but commonly symptomatic presentation in adults and adolescents. Since MS presents usually in young adults, and bolstered by the observation that MS risk is increased following an episode of EBV, a relationship between EBV and MS has been hypothesized. The study population was the participants of the Nurses’ Health Study (n = 62,439), of whom 144 developed MS. Antibody titers to EBV and cytomegalovirus (CMV) were compared between MS patients and age-matched controls. Of the 144 women with MS, 18 had blood samples collected before disease onset, and hence were able to be analyzed for antibody titers to EBV.
Prediagnosis mean antibody titers to EBV were significantly higher in MS patients than in matched controls. For the EBNA-2 antibody, a 4-fold difference in titers was associated with a marked increase in relative risk of MS (RR = 3.9). No association between CMV antibodies and MS was discernible. Ascherio and colleagues conclude that this study supports the hypothesis that EBV plays an etiologic role in MS.
Ascherio A, et al. JAMA. 2001;286: 3083-3088.
Coronary Magnetic Resonance Angiography for the Detection of Coronary Stenoses
Coronary angiography (cANG) is the current gold standard for diagnosis of clinically significant coronary artery disease (CAD), which is generally designated as greater than 50% reduction in luminal diameter. Despite its widespread use and utility, cANG is invasive, costly, and associated with some not-insubstantial risks. Hence, noninvasive modalities for diagnosis of CAD are an attractive alternative.
This report examined a direct comparison of cANG and coronary magnetic resonance angiography (cMRA), in 109 persons who underwent both methods of evaluation during the same diagnostic encounter. Within less than 2 weeks after cMRA, all patients underwent cANG. Most of the subjects were male, with a history of chest pain.
The sensitivity of cMRA in identifying clinically significant CAD was 93%. "Missed" CAD was comprised of isolated single-vessel disease, half of which was left circumflex artery involvement. Isolated left circumflex CAD, however, was seen in only 4% of subjects.
Advantages of cMRA include that absence of radiation and contrast dye, and its previously demonstrated superiority to cANG in persons with anomalous coronary vessels.
Kim WY, et al. N Engl J Med. 2001; 345:1863-1869.
Vitamin A Intake and Hip Fractures Among Postmenopausal Women
Vitamin A and its analogues (VitA) have been shown to produce changes in bone metabolism and structure that would logically increase risk of fracture. In animals, retinoic acid decreases osteoblast activity and activates osteoclasts, as well as inhibiting vitamin D activity. Yet, recent studies have been inconclusive about the potentially toxic effect of VitA intake on bone health in humans. This report involves an 18-year prospective analysis of participants in the Nurses’ Health Study studying the relationship between hip fracture and VitA intake, including foods and supplement ingestion.
During the period of observation, there were 603 hip fractures. Risk of fracture in the highest quintile of VitA (which includes food and supplements) was 1½ times greater than the risk in the lowest quintile. This adverse association may possibly underestimate the potential bone toxicity of high VitA intake because women with higher intake also tended to smoke less and exercise more! Feskanich and colleagues conclude that chronic intake of high amounts of VitA increases risk of hip fractures in women. Since the study population was dominantly populated with white women, whether other ethnicities experience the same effects remains unknown.
Feskanich D, et al. JAMA. 2002;287: 47-54.
Kuritzky, MD, Clinical Assistant Professor, University of Florida, Gainesville, is Associate Editor of Internal Medicine Alert.
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