Abstract：
:Trialists argue about the usefulness of stratified randomization. For investigators designing trials and readers who use them, the argument has created uncertainty regarding the importance of stratification. In this paper, we review stratified randomization to summarize its purpose, indications, accomplishments, and alternatives. In order to identify research papers, we performed a Medline search for 1966-1997. The search yielded 33 articles that included original research on stratification or included stratification as the major focus. Additional resources included textbooks. Stratified randomization prevents imbalance between treatment groups for known factors that influence prognosis or treatment responsiveness. As a result, stratification may prevent type I error and improve power for small trials (<400 patients), but only when the stratification factors have a large effect on prognosis. Stratification has an important effect on sample size for active control equivalence trials, but not for superiority trials. Theoretical benefits include facilitation of subgroup analysis and interim analysis. The maximum desirable number of strata is unknown, but experts argue for keeping it small. Stratified randomization is important only for small trials in which treatment outcome may be affected by known clinical factors that have a large effect on prognosis, large trials when interim analyses are planned with small numbers of patients, and trials designed to show the equivalence of two therapies. Once the decision to stratify is made, investigators need to chose factors carefully and account for them in the analysis.
journal_name
J Clin Epidemioljournal_title
Journal of clinical epidemiologyauthors
Kernan WN,Viscoli CM,Makuch RW,Brass LM,Horwitz RIdoi
10.1016/s0895-4356(98)00138-3subject
Has Abstractpub_date
1999-01-01 00:00:00pages
19-26issue
1eissn
0895-4356issn
1878-5921pii
S0895435698001383journal_volume
52pub_type
杂志文章,评审abstract：:We investigated the value of the ankle-brachial systolic pressure index (ABPI) as a test for the diagnosis of peripheral arterial occlusive disease (PAOD) in general practice. ABPI measurements on 231 legs of 117 subjects performed in three general practice centers (GPC) were compared with the diagnostic conclusions o...
journal_title：Journal of clinical epidemiology
pub_type： 杂志文章,多中心研究
doi：10.1016/s0895-4356(96)00275-2
更新日期：1996-12-01 00:00:00
abstract：:This paper focuses on the appropriateness of outcome measures to evaluate trauma care. The preventable death rate (PDR), based on the study of deceased patients only, has been the traditional measure of the impact of trauma care on improving the survival of patients with severe trauma. Another measure frequently used ...
journal_title：Journal of clinical epidemiology
pub_type： 杂志文章
doi：10.1016/0895-4356(90)90125-9
更新日期：1990-01-01 00:00:00
abstract：:The aim of the study was to determine coronary events in a defined Sudanese population. All coronary events occurring in Khartoum, the capital of Sudan, were registered during the calendar year 1989. The cold pursuit method of identifying coronary events by surveillance of routinely collected data was adopted. A total...
journal_title：Journal of clinical epidemiology
pub_type： 杂志文章
doi：10.1016/0895-4356(96)00116-3
更新日期：1996-09-01 00:00:00
abstract：OBJECTIVES:It is difficult to compare the reliability of triage systems with the kappa statistic. In this article, a method for comparing triage systems was developed and applied to previously conducted triage reliability studies. STUDY DESIGN AND SETTING:From simulations with theoretical distributions, the minimum, n...
journal_title：Journal of clinical epidemiology
pub_type： 杂志文章,评审
doi：10.1016/j.jclinepi.2010.01.012
更新日期：2010-11-01 00:00:00
abstract：OBJECTIVE:The objective was to estimate the presence and extent to which potentially unnecessary and therefore maybe wasteful clinical trials regarding relevant interventions and outcomes in major clinical areas had been conducted. STUDY DESIGN AND SETTING:From current Cochrane collaboration systematic reviews in majo...
journal_title：Journal of clinical epidemiology
pub_type： 杂志文章
doi：10.1016/j.jclinepi.2016.11.003
更新日期：2017-02-01 00:00:00
abstract：:Although previous studies document that blood pressure measured in the clinic may differ significantly from blood pressure recorded over 24 hours, the impact of these differences on patient selection for therapeutic drug trials is unknown. A placebo controlled double-blind evaluation of an experimental antihypertensiv...
journal_title：Journal of clinical epidemiology
pub_type： 临床试验,杂志文章
doi：10.1016/0895-4356(89)90046-2
更新日期：1989-01-01 00:00:00
abstract：OBJECTIVE:To determine the frequency of unpublished systematic reviews (SRs) and explore factors contributing to their occurrence. STUDY DESIGN AND SETTING:First or corresponding authors from a sample of SRs published in 2005 were asked to participate in a 26-item survey administered through the Internet, facsimile, a...
journal_title：Journal of clinical epidemiology
pub_type： 杂志文章
doi：10.1016/j.jclinepi.2008.09.014
更新日期：2009-06-01 00:00:00
abstract：BACKGROUND:There is no population-based prospective study concerning the relation between serum albumin and mortality in a non-Western population, and few previous studies included the subgroup analysis stratified by serum cholesterol level. METHODS:A 13.7-year cohort study was conducted on 6,957 males and females age...
journal_title：Journal of clinical epidemiology
pub_type： 杂志文章
doi：10.1016/j.jclinepi.2004.02.019
更新日期：2004-11-01 00:00:00
abstract：:The nature of variability in menstrual function has not been adequately described or quantified across the reproductive life span. This article evaluates the applicability of the bipartite model approach to the analysis of menstrual data and the relative importance of within-woman variability across the reproductive l...
journal_title：Journal of clinical epidemiology
pub_type： 杂志文章
doi：10.1016/s0895-4356(99)00202-4
更新日期：2000-07-01 00:00:00
abstract：BACKGROUND:The probability of a disease, given the result of two diagnostic tests, can be calculated by multiplying the odds of disease after the first test by the likelihood ratio of the second test. OBJECTIVE:To illustrate the error that occurs when calculating disease probability by combining the results of tests t...
journal_title：Journal of clinical epidemiology
pub_type： 杂志文章
doi：10.1016/j.jclinepi.2009.04.010
更新日期：2009-12-01 00:00:00
abstract：OBJECTIVES:To assess the role of quality of work-life (QWL) research in a clinical research environment. STUDY DESIGN AND SETTING:A phenomenological qualitative research study was conducted. This research was conducted in a large Canadian ambulatory cancer treatment center that serves over 2.3 million people in Ontari...
journal_title：Journal of clinical epidemiology
pub_type： 杂志文章
doi：10.1016/j.jclinepi.2006.03.003
更新日期：2008-05-01 00:00:00
abstract：INTRODUCTION:Weight loss interventions often present small mean weight changes over time, despite the fact that a substantial proportion of the participants lost more weight. This effect is often leveled out by the substantial proportion of participants who gained weight during the trial. The aim of this study is to id...
journal_title：Journal of clinical epidemiology
pub_type： 杂志文章,随机对照试验
doi：10.1016/j.jclinepi.2014.03.007
更新日期：2014-08-01 00:00:00
abstract：:The basic objective of this paper is to evaluate an age-comorbidity index in a cohort of patients who were originally enrolled in a prospective study to identify risk factors for peri-operative complications. Two-hundred and twenty-six patients were enrolled in the study. The participants were patients with hypertensi...
journal_title：Journal of clinical epidemiology
pub_type： 杂志文章
doi：10.1016/0895-4356(94)90129-5
更新日期：1994-11-01 00:00:00
abstract：:The objective of this study was to identify characteristics of non-respondents and late respondents to a mailed health survey. Persons who returned and those who did not return the questionnaire were compared using health insurance data, which indicated their age, sex, and health care expenditures in the previous year...
journal_title：Journal of clinical epidemiology
pub_type： 杂志文章
doi：10.1016/s0895-4356(97)00166-2
更新日期：1997-10-01 00:00:00
abstract：OBJECTIVES:To solicit experiences with and perceptions of rapid reviews from stakeholders, including researchers, policy makers, industry, journal editors, and health care providers. STUDY DESIGN AND SETTING:An international survey of rapid review producers and modified Delphi. RESULTS:Forty rapid review producers re...
journal_title：Journal of clinical epidemiology
pub_type： 杂志文章
doi：10.1016/j.jclinepi.2015.08.012
更新日期：2016-02-01 00:00:00
abstract：BACKGROUND AND OBJECTIVE:Two methods for measuring insulin sensitivity, fasting plasma insulin (FPI) and homeostasis model assessment (HOMA) have been proposed for use in large epidemiological research and clinical practice. This project describes the range of observed values of the HOMA and FPI in a large sample of th...
journal_title：Journal of clinical epidemiology
pub_type： 杂志文章
doi：10.1016/j.jclinepi.2004.05.001
更新日期：2004-11-01 00:00:00
abstract：OBJECTIVE:To develop a culturally adapted Bengali version of the Short Form-36 (SF-36) Health Survey and to test its acceptability, reliability, and validity in patients with rheumatoid arthritis (RA). STUDY DESIGN AND SETTING:The US English SF-36 was translated into Bengali after established cross-cultural adaptation...
journal_title：Journal of clinical epidemiology
pub_type： 杂志文章
doi：10.1016/j.jclinepi.2012.05.004
更新日期：2012-11-01 00:00:00
abstract：OBJECTIVE:To investigate the behavior of predictive performance measures that are commonly used in external validation of prognostic models for outcome at intensive care units (ICUs). STUDY DESIGN AND SETTING:Four prognostic models (Simplified Acute Physiology Score II, the Acute Physiology and Chronic Health Evaluati...
journal_title：Journal of clinical epidemiology
pub_type： 杂志文章
doi：10.1016/j.jclinepi.2006.08.011
更新日期：2007-05-01 00:00:00
abstract：:Event monitoring was first suggested 25 years ago as a way of detecting adverse reactions to drugs. Prescription-event monitoring (PEM), which has been developed by the Drug Safety Research Unit, is the first large-scale systematic post-marketing surveillance method to use event monitoring in the U.K. PEM identifies p...
journal_title：Journal of clinical epidemiology
pub_type： 杂志文章
doi：10.1016/0895-4356(90)90140-k
更新日期：1990-01-01 00:00:00
abstract：:Cross-sectional data from the Epidemiology of Diabetes Complications Study were used to examine the relationships between waist to hip circumference ratio (WHR) and the presence of diabetes complications in IDDM adults ages 18-45 years (N = 586). Significantly higher WHRs were observed among both genders with prolifer...
journal_title：Journal of clinical epidemiology
pub_type： 杂志文章
doi：10.1016/0895-4356(94)90291-7
更新日期：1994-05-01 00:00:00
abstract：OBJECTIVE:Adding risk factors to a prediction model often increases the area under the receiver operating characteristic curve (AUC) only slightly, particularly when the AUC of the model was already high. We investigated whether a risk factor that minimally improves the AUC may nevertheless improve the predictive abili...
journal_title：Journal of clinical epidemiology
pub_type： 杂志文章
doi：10.1016/j.jclinepi.2016.07.002
更新日期：2016-11-01 00:00:00
abstract：OBJECTIVES:Meta-analyses inform clinical practice by summarizing treatment effect estimates based on results from several trials. However, the statistical significance of a meta-analysis (i.e., whether the pooled treatment effect is statistically significant or not) may rely on the outcome of only a few patients from s...
journal_title：Journal of clinical epidemiology
pub_type： 杂志文章
doi：10.1016/j.jclinepi.2019.03.012
更新日期：2019-07-01 00:00:00
abstract：OBJECTIVES:To illustrate how multiple hypotheses testing can produce associations with no clinical plausibility. STUDY DESIGN AND SETTING:We conducted a study of all 10,674,945 residents of Ontario aged between 18 and 100 years in 2000. Residents were randomly assigned to equally sized derivation and validation cohort...
journal_title：Journal of clinical epidemiology
pub_type： 杂志文章
doi：10.1016/j.jclinepi.2006.01.012
更新日期：2006-09-01 00:00:00
abstract：OBJECTIVE:We examined the analytic validity of reported family history of hypertension and diabetes among siblings in the Seychelles. STUDY DESIGN AND SETTING:Four hundred four siblings from 73 families with at least two hypertensive persons were identified through a national hypertension register. Two gold standards ...
journal_title：Journal of clinical epidemiology
pub_type： 杂志文章
doi：10.1016/j.jclinepi.2003.10.008
更新日期：2004-05-01 00:00:00
abstract：OBJECTIVE:Exposure to ultraviolet radiation has consistently been linked to an increased risk of melanoma. Epidemiologic studies are susceptible to measurement error, which can distort the magnitude of observed effects. Although the reliability of self-report of many sun exposure factors has been previously described i...
journal_title：Journal of clinical epidemiology
pub_type： 杂志文章
doi：10.1016/j.jclinepi.2004.09.004
更新日期：2005-04-01 00:00:00
abstract：OBJECTIVE:To demonstrate how decision analytic models (DAMs) can be used to quantify impact of using a (diagnostic or prognostic) prediction model in clinical practice and provide general guidance on how to perform such assessments. STUDY DESIGN AND SETTING:A DAM was developed to assess the impact of using the HEART s...
journal_title：Journal of clinical epidemiology
pub_type： 杂志文章
doi：10.1016/j.jclinepi.2019.07.010
更新日期：2019-11-01 00:00:00
abstract：:The microbial flora on the surfaces of 15 books obtained from a public library and from 15 books obtained from a family household were studied. Staphylococcus epidermidis was recovered from 4 of the library books and 3 of the family household books. The number of organisms per page was between one to four. This data i...
journal_title：Journal of clinical epidemiology
pub_type： 杂志文章
doi：10.1016/0895-4356(94)90103-1
更新日期：1994-10-01 00:00:00
abstract：OBJECTIVE:We aimed to determine to what extent covariate adjustment could affect power in a randomized controlled trial (RCT) of a heterogeneous population with traumatic brain injury (TBI). STUDY DESIGN AND SETTING:We analyzed 14-day mortality in 9,497 participants in the Corticosteroid Randomization After Significan...
journal_title：Journal of clinical epidemiology
pub_type： 杂志文章,随机对照试验
doi：10.1016/j.jclinepi.2011.08.012
更新日期：2012-05-01 00:00:00
abstract：:We examined whether sociodemographic, health, and psychosocial factors predict stage at diagnosis in 444 women aged 55-84 with newly diagnosed, microscopically confirmed breast cancer. Stage was defined as local or advanced (regional or remote). One of the most interesting predictors of disease stage was living arrang...
journal_title：Journal of clinical epidemiology
pub_type： 杂志文章
doi：10.1016/0895-4356(93)90021-r
更新日期：1993-05-01 00:00:00
abstract：OBJECTIVES:Several methods exist to calculate sample size for the difference of proportions (risk difference). Researchers are often unaware that there are different formulae, different underlying assumptions, and what the impact of choice of formula is on the calculated sample size. The aim of this study was to discus...
journal_title：Journal of clinical epidemiology
pub_type： 杂志文章
doi：10.1016/j.jclinepi.2013.10.008
更新日期：2014-05-01 00:00:00
