Randomized controlled trials RCTs

The question whether lutein and zeaxanthin can contribute to lowering the risk for AMD cannot be answered unequivocally by epidemiological studies. Only randomized controlled trials (RCTs) during the course of which xanthophylls are supplemented in a double-blind, placebo-controlled, and randomized manner, and in which results are evaluated according to clear predefined efficacy criteria (Seddon and Hennekens 1994) have the potential to provide definitive answers. The specific long-term time-course and intricate nature of AMD make the design of such studies difficult, however. 

Stimulant treatment of ADHD has generated the largest body of treatment literature of any childhood psychiatric disorder. Between 1962 and 1993, over 250 reviews and over 3000 articles were published on stimulant effects (Swanson, 1993). By 1996, 161 randomized controlled trials (RCTs) had been published, encompassing 5 preschool, 150 school-age, 7 adolescent, and 9 adult studies. Improvement occurred in 65 %-75% of the children randomized to stimulants (meth-ylphenidate) [MPH] n = 133 trials dextroamphetamine [DEX] n = 22 trials pemoline [PEM] n = 6 trials) compared to 5%-30% of those assigned to pla-... 

Randomized controlled trials (RCTs) compare active therapy with placebo. Placebo should be as similar to the active therapy in appearance and feel as to be indistinguishable. This means that RCTs involving topical therapy are compared to the cream base, and the cream base most often has an independent function as a moisturizer. The potential effects of the cream base must be made explicit, as they may influence the efficacy of the product tested. By explicating the effect of the placebo arm of... 

Randomized controlled trials (RCTs) - seeking to isolate specific effects of different treatments on outcomes. Patients are randomly assigned to treatment groups to ensure comparability on all factors influencing outcomes with the exception of the treatment investigated. The treatment may or may not be delivered with patients unaware of which group they have been allocated to. 

The randomized controlled trial (RCT) is the de facto standard for studies of the health effects of medical interventions. In these studies, patients are randomized to receive either a therapy to be tested or an alternative (either a placebo or a conventional treatment), and an outcome is measured. RCTs have been used to evaluate therapeutic interventions, including drugs, radiation therapy, and surgical interventions, among others. The measured outcomes vary from hard evidence, such as mortality and morbidity, to softer evidence, such as patient-reported satisfaction and surrogate end points typified by markers of disease activity... 

Other critics state that EBM considers randomized, controlled trials (RCTs) as the only evidence to be used in clinical decision making. AcmaUy, EBM seeks the best existing evidence from basic science to clinical research with which to inform clinical decision. For example, a decision about the accuracy of a diagnostic test is best informed by evidence from a cross-sectional study, not an RCT. A cohort study, not an RCT, best answers a question about prognosis. However, in selecting a treatment, the randomized trial is the best study design to provide the most accurate estimate of treatment efficacy and safety. 

It must be said that how such information gets disseminated is controversial in the USA. A good recent example is an investigation of atovaquone vs. i.v. pentamidine in the treatment of mild to moderate Pneumocystis carinii pneumonia. This report included a decision tree to estimate the costs and cost-effectiveness of atovaquone vs. Pentamidine for cotrimoxazole-intolerant patients (Zarkin et al 1996). Clinical outcomes were based on data from a previous randomized controlled trial (RCT) (Phase III) comparing the two medications, while economic outcomes were based on... 

Mortality Folic add, vitamin B12 vitamin Be Homocysteine reduction Meta-analysis (MA) of randomized controlled trials (RCTs) no evidence of reduced risk Clarke et al. (2010)... 

Large randomized controlled trials (RCT) with long follow-up are considered to be the gold standard to demonstrate a significant mortality reduction due to screening. 

Gastrointestinal symptoms such as nausea, diarrhoea and abdominal pain were the most frequently reported side effects in multiple randomized controlled trials (RCTs) and reviews [92 , 101-104 - ], although a meta-analysis did not find a significant difference from placebo in six RCTs of azithromycin in chronic lung disease - potentially due to the generally lower doses used [105 ]. 

Dawodu A, Saadi HF, Bekdache G, Javed Y, Altaye M, Hollis BW. Randomized controlled trial (RCT) of vitamin D supplementation in pregnancy in a population with endemic vitamin D deficiency. J Clin Endocrinol Metab June 2013 98(6) 2337-46. 

There have been six randomized controlled trials(RCTs) of NIPPV for up to three months that have been published as full papers (11,18,23-26). Details of these studies are presented in Table 1. Strumpf et al. found no significant changes in any of the measured variables... 

Many of the randomized controlled trials (RCTs) investigating a protective role for antioxidant nutrients in cancer prevention (Table 3) have focused on / -carotene. A study in Linxian, China, of a rural population with poor nutritional status found that supplementation with a combination of / -carotene, selenium, and vitamin E for 5 years provided a 21% reduction in stomach cancer mortality and a 13% reduction in all cancer deaths. Although interesting, the population studied was likely to have very low intakes of a number of micronutrients and this study does not contribute to knowledge about the effects of individual antioxidants or offer any insight into their effects on populations with good nutritional status. 

Different kinds of evaluations have been conducted to determine the effect of repellents on disease incidence. Randomized controlled trials (RCTs) are currently considered to be the gold standard for testing the effectiveness of interventions for disease reduction in a population, provided that they are well conducted. The most important feature of an RCT is that the individuals recruited into the trial are randomly assigned to the intervention or a control, thereby minimizing selection and allocation bias to control as much as possible for both known and unknown confounders that... 

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