SEARCH · PubMed Health

Results for “Randomized trial”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 181 records · Page 10Linked to original sources

PubMedDate not supplied

Electronic trial banks: a complementary method for reporting randomized trials.

BACKGROUND: Randomized clinical trial (RCT) results are often difficult to find, interpret, or apply to clinical care. The authors propose that RCTs be reported into electronic knowledge bases-trial banks-in addition to being reported in text. What information should these trial-bank reports contain? METHODS: Using the competency decomposition method, the authors specified the ideal trial-bank contents as the information necessary and sufficient for completing the task of systematic reviewing. RESULTS: They decomposed the systematic reviewing task into four top-level tasks and 62 subtasks. 162 types of trial information were necessary and sufficient for completing these subtasks. These items relate to a trial's design, execution, administration, and results. CONCLUSION: Trial-bank publishing of these 162 items would capture into computer-understandable form all the trial information needed for critically appraising and synthesizing trial results. Decision-support systems that access shared, up-to-date trial banks could help clinicians manage, synthesize, and apply RCT evidence more effectively.

Databases, Factual↗

PubMed2002

Methods for the analysis of incidence rates in cluster randomized trials.

BACKGROUND: The published literature on cluster randomized trials focuses on outcomes that are either continuous or binary. In many trials, the outcome is an incidence rate, such as mortality, based on person-years data. In this paper we review methods for the analysis of such data in cluster randomized trials and present some simple approaches. METHODS: We discuss the choice of the measure of intervention effect and present methods for confidence interval estimation and hypothesis testing which are conceptually simple and easy to perform using standard statistical software. The method proposed for hypothesis testing applies a t-test to cluster observations. To control confounding, a Poisson regression model is fitted to the data incorporating all covariates except intervention status, and the analysis is carried out on the residuals from this model. The methods are presented for unpaired data, and extensions to paired or stratified clusters are outlined. RESULTS: The methods are evaluated by simulation and illustrated by application to data from a trial of the effect of insecticide-impregnated bednets on child mortality. CONCLUSIONS: The techniques provide a straightforward approach to the analysis of incidence rates in cluster randomized trials. Both the unadjusted analysis and the analysis adjusting for confounders are shown to be robust, even for very small numbers of clusters, in situations that are likely to arise in randomized trials.

Cluster Analysis↗

PubMed2005

Randomization inference for balanced cluster-randomized trials.

This paper discusses the choice of randomization tests for inferences from cluster-randomized trials that have been designed to ensure a balanced allocation of clusters to treatments. Methods for covariate-adjusted randomization tests are reviewed and their application to balanced cluster-randomized trials discussed. Two cluster-randomized trials with balanced designs are used to illustrate the choices that can be made in selecting a randomization test, and methods for obtaining confidence intervals for treatment effects are illustrated. The balance imposed by the randomization in these trials makes adjustment for covariates less beneficial than for an unbalanced design. However, the adjusted analyses do not appear generally to have worse properties than the unadjusted ones, and may provide protection against any imbalance that has not been controlled for in the design. The only case when adjustment for covariates may result in worse precision is when a large number of cluster-level covariates are included in the analysis. An expression is provided that allows the size of this effect to be calculated for any given set of cluster-level covariates.

Cluster Analysis↗

PubMed2005

Group sequential methods for cluster randomization trials with binary outcomes.

BACKGROUND: Cluster randomization trials in which intact social units are randomly assigned to different intervention groups have become very popular in recent years, particularly for the evaluation of innovations in the delivery of health care. An extensive literature dealing with the associated methodological challenges has also appeared. Although the monitoring of such trials using formal stopping rules is clearly indicated when the outcomes are irreversible and individual-level data are available sequentially, simple and reliable statistical methods that may be used for this purpose are currently not available. PURPOSE: To investigate the validity of standard group sequential methods when applied to cluster randomization trials having binary outcomes. METHODS: The large sample distributions for each of five test statistics computed from sequentially accumulated data are derived. A simulation study is performed to evaluate the finite sample properties of these statistics when applied to the interim analysis of cluster randomization trials. Data from the World Health Organization antenatal care trial are used to illustrate the methods. RESULTS: Each of the joint distributions is shown to be characterized by a covariance structure that asymptotically satisfies an independent increments structure, a foundation that simplifies group sequential methods. The simulation study reveals that four of the five test statistics evaluated provide satisfactory performance with as few as 10 clusters allocated to each of two interventions. LIMITATIONS: The applicability of our results to effect estimation following a group sequential cluster randomization trial is not investigated, although a theoretical foundation which may be used for this purpose is presented. CONCLUSIONS: Standard group sequential methods can be applied to cluster randomization trials when interim analyses are warranted.

Clinical Trials as Topic↗

PubMed1992

In situ versus reversed femoropopliteal vein grafts: long-term follow-up of a prospective, randomized trial.

In a prospective, randomized trial, 226 patients undergoing femoropopliteal bypass for lower limb ischaemia were allocated to reversed (123 patients) or in situ (103) techniques. The groups were comparable for age, sex, incidence of diabetes, and indications for surgery. Eleven veins were rejected at operation, nine in the reversed group and two in the in situ group, leaving 114 reversed and 101 in situ grafts for study. Cumulative patency rates were not significantly different between reversed and in situ grafts at any time up to 6 years after operation, with primary patency rates at 1, 3 and 5 years of 84.8, 69.5 and 62.4 per cent for reversed grafts and 79.9, 71.2 and 63.5 per cent for in situ grafts. Small vein grafts (< 4 mm in diameter) were associated with patency rates at 1, 3 and 5 years of 63.5, 46.7 and 36.0 per cent compared with 93.9, 82.5 and 75.9 per cent for vein grafts > or = 4 mm in diameter (P < 0.002, log rank test). The patency rates of small veins employed in situ and reversed were similar. The in situ technique confers neither short- nor long-term advantage over reversed vein grafting for femoropopliteal bypass.

Aged↗

PubMed2000

Hemorrhoidectomy vs. Lord's method: 17-year follow-up of a prospective, randomized trial.

PURPOSE: A prospective, randomized trial was performed between 1979 and 1981 comparing anal dilation and hemorrhoidectomy for hemorrhoidal disease at the Maastricht University Hospital. The aim of this study was to update that trial to assess long-term outcome and complications such as fecal incontinence. METHODS: A total of 138 patients with second-degree and third-degree hemorrhoids entered the study. Median follow-up was 17 (range, 8.4-18.3) years and was achieved for 118 (86 percent) patients. Group A (n = 35) underwent hemorrhoidectomy and Group B (n = 39) was treated with anal dilation and aftertreatment (original Lord's procedure), whereas Group C (n = 44) had dilation only. Fourteen of these patients died. RESULTS: Recurrent hemorrhoids were noted for 26 percent of the patients treated with hemorrhoidectomy, for 46 percent with operative dilation with the postoperative dilation program, and for 39 percent with operative dilation without the postoperative program. The percentage of repeated treatment for the three subgroups was 11, 23, and 18 percent, respectively. The continence status remained more or less the same during the first year. However, 17 years later the anal stretch procedures caused various incontinence disorders in 52 percent of these patients. Significance was found for incontinence of flatus (from 11 to 30 patients; P = 0.04) in the anal dilation groups. CONCLUSIONS: Hemorrhoidectomy can be considered to be a safe procedure for treatment of hemorrhoidal disease, with excellent long-term results. Anal dilation is associated with a high percentage of complaints of fecal incontinence. The procedure should be abandoned.

Adult↗

PubMed1995

Increase of birth weight following chloroquine chemoprophylaxis during the first pregnancy: results of a randomized trial in Cameroon.

A randomized trial was carried out from 1991 to 1993 among women attending an antenatal clinic in Ebolowa, Cameroon where malaria is hyperendemic and transmission occurs at a high level all year round. All pregnant women attending the clinic for their first prenatal visit between October 1991 and November 1992 were alternately assigned to chloroquine (CQ) or control (CT) groups. Chloroquine was given under observation at a weekly oral dose of 300 mg. At delivery, smears from maternal, cord, and placental blood were made and stained with Giemsa for parasites. An in vivo chloroquine sensitivity investigation was carried out on women attending the postnatal consultation to evaluate the level of chloroquine resistance in the target population. The efficacy of chloroquine was moderate in placental infection (39.2% infected in the CQ group versus 57.8% in the CT group: P = 0.05), probably because of a resistance to chloroquine estimated to be 10.9%. In the CQ group, the mean birth weight was significantly higher (P = 0.02) and the proportion of low birth weight newborns was lower (10.5% versus 27.7%; P = 0.02). A strong correlation between placental infection and birth weight was observed: the mean birth weight difference between infected and noninfected placentae was 359 g (P < 0.0001) and the proportion of low birth weight new born babies was 35.6% versus 5.9% (P = 0.0001). In Cameroon, in spite of a moderate resistance to chloroquine, this drug proved to be highly effective in increasing birth weight when administered to primigravidae. We therefore think such a prophylaxis should be recommended only to primigravidae in high transmission areas.

Adolescent↗

PubMed2005

Informed patient consent to participation in cluster randomized trials: an empirical exploration of trials in primary care.

Cluster randomized trials are increasingly common. Obtaining informed patient consent to participation in these trials raises practical challenges and ethical issues. The aims of this paper were to 1) develop a typology of interventions employed in cluster randomized trials in primary care; 2) assess whether the likelihood of seeking individual consent to participation varies by intervension type; 3) assess whether this likelihood has increased over time; 4) assess evidence for under reporting of consent procedures; 5) articulate reasons for not obtaining consent; and 6) make recommendations for future trial investigators. We collected data on trial interventions and consent procedures from reports of 152 recently published trials, and 47 unpublished trials. We develop a typology of interventions based on reasons for adopting a clustered design. We examine proportions seeking individual consent to participation among trials involving different types of intervention, in different periods, and among published and unpublished trials. Two-thirds of the trials had multifaceted interventions. Trials involving different types of intervention had different propensities to seek consent, largely because of practical obstacles to obtaining consent. Obtaining consent can compromise internal validity. More recent trials are no more likely to obtain consent than past trials. There was no evidence of under-reporting of consent procedures in publications. In conclusion, future trial investigators should consider both practical reasons and scientific arguments for not obtaining individual patient consent for all interventions in their trials. Where feasible, they should allow patients to opt out of the trial. Lay individuals should represent trial participants as part of the process of cluster consent to participation, and lay individuals could also be involved in considering ethical issues during trial planning. A more public debate may clarify the general acceptability of not obtaining consent in certain situations.

Biomedical Research↗

PubMed1995

Symptomatic outcome 1 year after laparoscopic and minilaparotomy cholecystectomy: a randomized trial.

In a randomized controlled trial, 299 patients were sent a symptoms questionnaire 1 year after laparoscopic (n = 151) or minilaparotomy (n = 148) cholecystectomy for symptomatic cholelithiasis. The response rate to the questionnaire from contactable patients was 86 per cent. In both groups, at least 90 per cent of patients reported that their symptoms were improved, and at least 93 per cent rated the success of their operation as 'excellent', 'good', or 'fair'. However, over half the patients reported abdominal pain, a quarter reported flatulence, and a quarter dyspepsia. The only difference between treatment groups was that a higher proportion of patients who underwent minilaparotomy reported heartburn (35 per cent versus 19 per cent, P = 0.005). Patients who reported a 'poor' outcome were more likely to have suffered a postoperative complication, had lower quality of life scores, and higher anxiety and depression scores. Both laparoscopic and minilaparotomy cholecystectomy result in symptomatic benefit in at least 90 per cent of patients with symptomatic cholelithiasis.

Abdominal Pain↗

PubMed1981

Superior gastric reduction procedure for morbid obesity: a prospective, randomized trial.

A prospective randomized clinical trial was undertaken to compare the effects of gastric bypass with Roux-en-Y gastrojejunostomy and a gastric partitioning procedure. Operative groups were comparable, with regard to preoperative weight, age, sex, historic findings and operative complications. Post-operative weight loss was followed for one year. Patients receiving the gastric partitioning procedure showed significantly poorer weight loss as early as three months postoperatively than did those receiving gastric bypass. This poorer performance persisted throughout the study period.

Adult↗

PubMed1985

Plasma exchange and prednisone in acute inflammatory polyradiculoneuropathy: a controlled randomized trial.

A controlled-randomized trial of plasma exchange combined with prednisone was compared to supportive care alone in patients with acute inflammatory polyradiculoneuropathy (AIP). The design of this study differs from other reported trials of plasma exchange in AIP because prednisone was used in the treatment group to prevent the possibility of antibody rebound. Furthermore, in this study, detailed muscle strength testing formed the principal basis for assessment of therapeutic efficacy while in the British, North American, and French studies, a functional assessment scale was used. Analysis of our data revealed no significant improvement in the treated group over the controls. The sample size, albeit small (12 treated and 13 controls), had the power (95% chance) to detect a change of two British Medical Research Council grades of strength between the groups. The difference in our results versus others (North American and French studies) probably reflects the adverse effects of prednisone on recovery in AIP. An additional consideration is that plasma exchange may have an overall modest effect on the course of AIP, less appreciated when individual muscles are tested compared to assessment by large functional categories.

Acute Disease↗

PubMed2002

The transitive fallacy for randomized trials: if A bests B and B bests C in separate trials, is A better than C?

BACKGROUND: If intervention A bests B in one randomized trial, and B bests C in another randomized trial, can one conclude that A is better than C? The problem was motivated by the planning of a randomized trial, where A is spiral-CT screening, B is x-ray screening, and C is no screening. On its surface, this would appear to be a straightforward application of the transitive principle of logic. METHODS: We extended the graphical approach for omitted binary variables that was originally developed to illustrate Simpson's paradox, applying it to hypothetical, but plausible scenarios involving lung cancer screening, treatment for gastric cancer, and antibiotic therapy for clinical pneumonia. RESULTS: Graphical illustrations of the three examples show different ways the transitive fallacy for randomized trials can arise due to changes in an unobserved or unadjusted binary variable. In the most dramatic scenario, B bests C in the first trial, A bests B in the second trial, but C bests A at the time of the second trial. CONCLUSION: Even with large sample sizes, combining results from a previous randomized trial of B versus C with results from a new randomized trial of A versus B will not guarantee correct inference about A versus C. A three-arm trial of A, B, and C would protect against this problem and should be considered when the sequential trials are performed in the context of changing secular trends in important omitted variables such as therapy in cancer screening trials.

Antineoplastic Combined Chemotherapy Protocols↗

PubMed1999

Simple sample size calculation for cluster-randomized trials.

BACKGROUND: Cluster-randomized trials, in which health interventions are allocated randomly to intact clusters or communities rather than to individual subjects, are increasingly being used to evaluate disease control strategies both in industrialized and in developing countries. Sample size computations for such trials need to take into account between-cluster variation, but field epidemiologists find it difficult to obtain simple guidance on such procedures. METHODS: In this paper, we provide simple formulae for sample size determination for both unmatched and pair-matched trials. Outcomes considered include rates per person-year, proportions and means. For simplicity, formulae are expressed in terms of the coefficient of variation (SD/mean) of cluster rates, proportions or means. Guidance is also given on the estimation of this value, with or without the use of prior data on between-cluster variation. CASE STUDIES: The methods are illustrated using two case studies: an unmatched trial of the impact of impregnated bednets on child mortality in Kenya, and a pair-matched trial of improved sexually-transmitted disease (STD) treatment services for HIV prevention in Tanzania.

Child, Preschool↗

PubMed1990

Tissue plasminogen activator (rt-PA) vs heparin in deep vein thrombosis. Results of a randomized trial.

We performed a randomized trial comparing two dosing regimens of recombinant tissue plasminogen activator (rt-PA) plus heparin vs heparin alone in the treatment of acute proximal deep vein thrombosis in 83 patients. Of 12 patients who received 0.5 mg/kg rt-PA plus heparin over 4 h, seven (58 percent) had greater than 50 percent lysis of the thrombus, compared with none of 12 who received placebo plus heparin (p = 0.002). Of 28 patients who received 0.5 mg/kg rt-PA over 8 h, repeated in 24 h, six (21 percent) had greater than 50 percent lysis, compared with two (7 percent) of 30 patients who received placebo plus heparin (p = 0.11). The 4-h infusion of rt-PA produced a 40 percent reduction and the 8-h infusion an 11 percent reduction in plasma fibrinogen concentration. At long-term follow-up, three (25 percent) of 12 patients in whom greater than 50 percent lysis was achieved had symptoms of the postphlebitic syndrome, compared with 19 (56 percent) of 34 patients in whom lysis was less than 50 percent (p = 0.07).

Double-Blind Method↗

PubMed2005

Prevention of upper respiratory tract infections by gargling: a randomized trial.

BACKGROUND: Gargling to wash the throat is commonly performed in Japan, and people believe that such hygienic routine, especially with gargle medicine, prevents upper respiratory tract infections (URTIs). Its effectiveness, however, has not been established by clinical trials. DESIGN: Randomized controlled trial carried out in 2002-2003 winter season and analyzed in 2003 and 2004. PARTICIPANTS: Healthy volunteers (387) aged 18 to 65 years. INTERVENTION: Participants were randomly assigned to water gargling, povidone-iodine gargling, and usual care (control). Subjects in the two gargling groups were requested to gargle with water or diluted povidone-iodine at least three times a day. Participants were followed for 60 days. MAIN OUTCOME MEASURES: The primary outcome measure was first URTI incidence. Severity of URTI symptoms among incident cases was also evaluated. Both outcomes were assessed with a self-administered symptom record. Analyses were performed on an intention-to-treat basis. RESULTS: A total of 130 participants contracted URTIs. The incidence rate of first URTI was 0.26 episodes/30 person-days among control subjects. The rate decreased to 0.17 episodes/30 person-days in the water gargling group, and 0.24 episodes/30 person-days in the povidone-iodine gargling group. Respective incidence rate ratios against controls were 0.64 (95% confidence interval [CI]=0.41-0.99) and 0.89 (95% CI=0.60-1.33). A Cox regression (proportional hazard model) revealed the efficacy of water gargling (hazard ratio=0.60, 95% CI=0.39-0.95). Even when a URTI occurred, water gargling tended to attenuate bronchial symptoms (p=0.055). CONCLUSIONS: Simple water gargling was effective to prevent URTIs among healthy people. This virtually cost-free modality would appreciably benefit the general population.

Adolescent↗

PubMed1985

The influence of jejunoileal ratio on plasma electrolytes and liver function in intestinal bypass for morbid obesity. A randomized trial.

In a randomized clinical trial 89 obese patients had end-to-side jejunoileostomy with either a 1:3 or a 3:1 ratio between jejunum and ileum left in continuity. The duration of postoperative observation was at least 36 months. Repeated assessments were made on plasma concentrations of sodium, potassium, bicarbonate, magnesium, calcium, aspartate aminotransferase, and clotting factors. The major findings were that bypass surgery (i) has no important influence on levels of sodium, bicarbonate, and calcium, (ii) induces potassium depletion and transient liver dysfunction of a degree that is independent of the jejunoileal ratio, and (iii) induces a greater magnesium depletion when a long jejunum and short ileum segment are left in continuity.

Clinical Trials as Topic↗

PubMed1982

Dopamine treatment of human cadaver kidney graft recipients: a prospectively randomized trial.

In a prospectively randomized trial, 50 human cadaver kidney graft recipients were tested for the effect of dopamine infusion on kidney function after transplantation. The kidneys were taken from beating-heart donors under optimal conditions. The dopamine infusion did not affect the dialysis frequency in the 1st week after transplantation, in the dopamine group only slightly better creatinine clearances could be detected. However, the diuresis increased significantly when dopamine was given and this resulted in the fact that in the dopamine group 47.4% of the patients were dialyzed although the diuresis amounted to more than 11/day as compared to 15.7% of such patients in the nondopamine group. These findings correspond to experimental data, which showed that the dopamine infusion of the recipient mainly ameliorated renal function in those cases where kidneys were taken after hypotensive injury of the donor.

Cadaver↗

PubMed1986

Prednisolone supplementation to Clomid and/or gonadotrophin stimulation for in-vitro fertilization--a prospective randomized trial.

In a prospective randomized trial, 73 patients received prednisolone, 7.5 mg daily, for one cycle in addition to Clomid and/or gonadotrophins, while another 73 patients were not given the corticosteroid. In-vitro fertilization (IVF) resulted in 16 versus six clinical pregnancies in the prednisolone and the non-prednisolone group, respectively (P less than 0.05). Oestrogen was significantly higher under prednisolone during the ovulatory phase, while LH was significantly lower. The adrenal androgen dehydroepiandrosterone sulphate was markedly depressed by prednisolone and testosterone was also markedly lower in the prednisolone group. A stress-related androgen excess might occur in some patients undergoing IVF with consequent cystic degeneration of some follicles as in polycystic ovarian disease. Prednisolone might counteract this detrimental effect by depressing adrenal and ovarian androgens.

Clomiphene↗