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Showing papers in "Controlled Clinical Trials in 1986"


Journal ArticleDOI
TL;DR: This paper examines eight published reviews each reporting results from several related trials in order to evaluate the efficacy of a certain treatment for a specified medical condition and suggests a simple noniterative procedure for characterizing the distribution of treatment effects in a series of studies.

33,234 citations


Journal ArticleDOI
TL;DR: Because the clinics in a multiclinic randomized clinical trial represent neither fixed stratification effects nor random classificatory effects, the appropriate analysis of data from such a trial has been the subject of controversy and debate.

399 citations


Journal ArticleDOI
TL;DR: It is argued that this idea should be extended to obtain the predictive power of the trial, derived by averaging the conditional power with respect to the current belief about the unknown parameters.

244 citations


Journal ArticleDOI
TL;DR: The development of the first of these four elements of a database of perinatal trials is described, which will ultimately comprise four main elements: a register of published reports of trials; aregister of unpublished trials; an ongoing and planned trials; and data derived from pooled overviews (meta-analyses) of trials.

137 citations


Journal ArticleDOI
TL;DR: The SHEP experience indicates that older persons are willing to volunteer for clinical trials research and that problems of inference are probably not any greater for that age group than for any other.

93 citations


Journal ArticleDOI
TL;DR: A method of adjusting event rates in the presence of time-dependent rates of losses, noncompliance, and the like for sample size calculation is presented.

92 citations


Journal ArticleDOI
TL;DR: Numerical examples showed that, by ordering the sample space using the likelihood principle, the method is able to shorten the length of the intervals and to obtain more accurate coverage of probability relative to previously proposed methods.

79 citations


Journal ArticleDOI
TL;DR: The monitoring of quality measurement of blood pressure in a large clinical trial such as MRFIT must be a two-pronged effort that considers observation and evaluation of methods of measuringBlood pressure in actual clinical practice and evaluationof data resulting from these procedures.

72 citations


Journal ArticleDOI
TL;DR: In this article, the authors examined the restricted mean as an index for comparing survival in two groups and then extended the method to incorporate covariates into the analysis, and explored the assumption of piecewise exponentiality is shown to be rather mild.

27 citations


Journal ArticleDOI
TL;DR: Several approaches, including the use of conditional power, can be used to help the monitoring committee decide if a study should be stopped early because of a harmful or insufficiently effective treatment.

26 citations


Journal ArticleDOI
TL;DR: The Systolic Hypertension in the Elderly Program (SHEP) Pilot was a collaborative clinical trial that distributed to the clinics all data processing tasks except for randomization assignment codes and morbidity and mortality data.

Journal ArticleDOI
TL;DR: It is found that there are many circumstances in which, in spite of eliminating carryover, the use of baseline measurements provides a less powerful test of treatment effect and a less precise estimate of the treatment difference.

Journal ArticleDOI
TL;DR: The acquisition of quality biochemical data in the MRFIT was enhanced by writing detailed protocols, instituting strict rules for collecting and shipping specimens, setting high goals for analytical performance, using reliable means to transfer data, employing dedicated and competent analysts, and having a director of the Central Laboratory who believed in and enforced an effective quality control system.

Journal ArticleDOI
TL;DR: The National Death Index (NDI) is a central file of identifying information on all deaths occurring in the United States since 1979 as discussed by the authors, which is used as a tool for both short-term and long-term follow-up in cancer treatment, prevention, and occupational studies.


Journal ArticleDOI
TL;DR: The system developed for processing data in the MRFIT has several advantages: it satisfies the requirements identified by Karrison or a system of data editing and control, it is largely self-documenting as a result of the data dictionary approach taken, and it is easily adaptable to other clinical studies.

Journal ArticleDOI
TL;DR: The MRFIT nutrition intervention program was designed with the need for interclinic comparability of intervention techniques in mind, and required not only development of study-wide nutrition intervention materials, but also necessitated ongoing attention to staff training and monitoring procedures in order to ensure intercenterComparability of efforts.

Journal ArticleDOI
TL;DR: The design and implementation of a general data processing system to accommodate several different epidemiologic studies to be conducted by a new research group and has been used successfully in three studies differing in design, size, data collection locale, and rate of data accrual.

Journal ArticleDOI
TL;DR: Comparison of data obtained from a population-based regional tumor registry revealed an accrual rate of more than 80%, which strongly illustrates the necessity of matching to a population register before presenting data of such trials.

Journal ArticleDOI
TL;DR: If one assumes that treatment groups have been successfully balanced by randomization, then ANCOVA is more powerful than the t-test under a broad range of conditions; this is true even in the model assumed by the t -test, and regardless of the presence of measurement error.

Journal ArticleDOI
TL;DR: Pulmonary function testing was used in MRFIT to monitor the presence of airways disease and to assess changes in pulmonary function over time and centralized training in testing techniques and spirometer maintenance was strongly recommended.

Journal ArticleDOI
TL;DR: It is evident that many long-term trials do not contain adequate data on withdrawals, and readers of published trials are seldom able to judge whether or not withdrawals might affect the final results.

Journal ArticleDOI
TL;DR: This paper presents a graphical method for converting relative risks to absolute risks and illustrates the importance of competing mortal hazard from other causes on absolute cancer risk.

Journal ArticleDOI
TL;DR: Quality control is of particular importance in multicenter trials, not only because of the complexity of such studies, but Because of the necessity that data obtained in a variety of settings be obtained.

Journal ArticleDOI
TL;DR: It is shown that the multivariate approach is a useful addition to the standard technique for display of multivariate, clinical analgesic data, the biplot, which is based on principal component analysis.

Journal ArticleDOI
TL;DR: The screening procedure of the Multiple Risk Factor Intervention Trial (MRFIT) consisted of three screening visits, with 361,662 men seen at the first of these visits, where individuals found to be at above average risk based on elevated diastolic blood pressure, serum cholesterol, and cigarette use were invited to the second screening visit.

Journal ArticleDOI
TL;DR: Quality control was emphasized in the screening and clinic laboratory during the early stages of the trial to cover all aspects of screening, and in the later stages to cover local testing used to monitor the participant in the clinic and to guarantee collection of valid specimens to be shipped to the Central Laboratory.