Antioxidant vitamin supplementation for preventing and slowing the progression of age-related cataract.

BACKGROUND: Age-related cataract is a major cause of visual impairment in the elderly. Oxidative stress has been implicated in its formation and progression. Antioxidant vitamin supplementation has been investigated in this context. OBJECTIVES: To assess the effectiveness of antioxidant vitamin supplementation in preventing and slowing the progression of age-related cataract. SEARCH METHODS: We searched CENTRAL (which contains the Cochrane Eyes and Vision Group Trials Register) (The Cochrane Library 2012, Issue 2), MEDLINE (January 1950 to March 2012), EMBASE (January 1980 to March 2012), Latin American and Caribbean Literature on Health Sciences (LILACS) (January 1982 to March 2012), Open Grey (System for Information on Grey Literature in Europe) (www.opengrey.eu/), the metaRegister of Controlled Trials (mRCT) (www.controlled-trials.com), ClinicalTrials.gov (www.clinicaltrials.gov) and the WHO International Clinical Trials Registry Platform (ICTRP) (www.who.int/ictrp/search/en). There were no date or language restrictions in the electronic searches for trials. The electronic databases were last searched on 2 March 2012. We also checked the reference lists of included studies and ongoing trials and contacted investigators to identify eligible randomized trials. SELECTION CRITERIA: We included only randomized controlled trials in which supplementation with one or more antioxidant vitamins (beta-carotene, vitamin C and vitamin E) in any form, dosage or combination for at least one year was compared to another antioxidant vitamin or to placebo. DATA COLLECTION AND ANALYSIS: Two authors extracted data and assessed trial quality independently. We pooled results for the primary outcomes, i.e., incidence of cataract and incidence of cataract extraction. We did not pool results of the secondary outcomes - progression of cataract and loss of visual acuity, because of differences in definitions of outcomes and data presentation. We pooled results by type of cataract when data were available. We did not perform a sensitivity analysis. MAIN RESULTS: Nine trials involving 117,272 individuals of age 35 years or older are included in this review. The trials were conducted in Australia, Finland, India, Italy, the United Kingdom and the United States, with duration of follow-up ranging from 2.1 to 12 years. The doses of antioxidant vitamins were higher than the recommended daily allowance. There was no evidence of effect of antioxidant vitamin supplementation in reducing the risk of cataract, cataract extraction, progression of cataract or in slowing the loss of visual acuity. In the pooled analyses, there was no evidence of effect of beta-carotene supplementation in reducing the risk of cataract (two trials) (relative risk (RR) 0.99, 95% confidence interval (CI) 0.91 to 1.08; n = 57,703) or in reducing the risk of cataract extraction (three trials) (RR 1.00, 95% CI 0.91 to 1.10; n = 86,836) or of vitamin E supplementation in reducing the risk of cataract (three trials) (RR 0.97, 95% CI 0.91 to 1.04; n = 50,059) or of cataract extraction (five trials) (RR 0.98, 95% CI 0.91 to 1.05; n = 83,956). The proportion of participants developing hypercarotenodermia (yellowing of skin) while on beta-carotene ranged from 7.4% to 15.8%. AUTHORS' CONCLUSIONS: There is no evidence from RCTs that supplementation with antioxidant vitamins (beta-carotene, vitamin C or vitamin E) prevents or slows the progression of age-related cataract. We do not recommend any further studies to examine the role of antioxidant vitamins beta-carotene, vitamin C and vitamin E in preventing or slowing the progression of age-related cataract. Costs and adverse effects should be weighed carefully with unproven benefits before recommending their intake above recommended daily allowances.

A simulation-based biodefense and disaster preparedness curriculum for internal medicine residents.

AIMS: Disaster and bioterrorism preparedness is poorly integrated into the curricula of internal medicine residency programs. Given that victims may present to a variety of healthcare venues, including primary care practices, inpatient hospital wards, and intensive care units, we developed a curriculum to address this need. METHODS: The curriculum consisted of four didactic sessions with supplemental readings covering biologic, chemical, and radiologic agents, as well as public health infrastructure. All 30 internal medicine resident participants also underwent a four hour training seminar at a high fidelity human simulation center. Instruction included the use of personal protective equipment (PPE)and participation in simulated scenarios utilizing technologically sophisticated mannequins with monitoring and interactive capability. Sessions were videotaped, reviewed with participants, and followed by self-evaluation and constructive feedback. RESULTS: Compared to a control group of residents who did not undergo training, the participants' level of knowledge was significantly better, with mean objective test scores of 66.8%+/-11.8% SD vs. 50%+/-13.1% SD, p < 0.0001. Although there was a trend toward increasing knowledge with increasing level of training in the control group, this difference was not significant. Subjective preparedness was also significantly better in the intervention group (p < 0.0001). Objective improvements were not maintained after one year. CONCLUSIONS: In this pilot study, a disaster-preparedness curriculum including simulation-based training had a positive effect on residents' knowledge base and ability to respond to disaster. However, this effect had diminished after one year, indicating the need for reinforcement at regular intervals.