Prevalence study of the randomized controlled trials in the Journal of Intellectual Disability Research: 1957-1994. Cumulative meta-analysis of clinical trials builds evidence for exemplary medical care.
Systematic reviews of care are increasingly potent guides to clinical practice, and it is important that all relevant randomized controlled trials (RCTs) are identified by those within the speciality of learning disability who produce such works. All RCTs in the Journal of Intellectual Disability Research and its predecessor were identified by hand-searching (1957-1994), and the frequency, origin, intervention and quality of reporting of randomization were described. Electronic searches for the trials were undertaken for the years 1974-1994, and the quality of indexing was inspected and tested. These electronic searches were then compared to a 'gold standard' search. Fifty-six RCTs were identified. None contained the world 'randomized' in the title and only nine mentioned it in the abstract. Out of the 37 RCTs published between 1974 and 1994, 36 are in PsycLIT and 37 in MEDLINE. One MEDLINE record contained the wrong abstract. The methodological phrases used in the electronic records were poor, and thus, the precision of electronic searches, using both databases, was low. This international journal contains many relevant RCTs from around the world, involving several types of interventions. Unfortunately, these trials cannot be readily accessed electronically using methodological phrases designed to find RCTs. Improved quality of indexing would facilitate identification of RCTs and their dissemination. Cumulative meta-analysis of clinical trials (a Bayesian interpretation for accumulating evidence) will profoundly affect medical care by summarizing evidence in the assessment of technology innovations. Application of the technique to the randomized control trials (RCTs) of streptokinase treatment of acute myocardial infarction, reduction of peri-operative mortality by antibiotic prophylaxis, and prevention of death from bleeding peptic ulcers has revealed efficacy years before it was suspected by any other means. Arrangement of the trials according to event rate in the controls, effect sizes, quality of the trials or according to covariables of interest has supplied unique information. If carried out prospectively the technique supplies invaluable information regarding indications for another trial, the number of patients necessary to determine the validity of past trends, and the type of patients who might be benefitted. Careful examination in a cumulative manner of the prior trials can reduce the need for future large trials.
As only three relevant RCTs were identified, we have limited capacity to compare the benefits and harms of medical interventions currently used for treating EE. Further RCTs on therapies for EE are required.