SEARCH · PubMed Health

Results for “Randomized controlled trials”

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 919 records · Page 51Linked to original sources

PubMed2000

Methodological issues in randomized controlled trials.

There is increasing emphasis on the need to practise evidence-based medicine and the strongest evidence comes from well designed and well-conducted randomized controlled trials. Every component is important for the success of a clinical trial; if the design or sample size is inappropriate, then the results of the study will be unreliable, however well the study is conducted. Conversely a well-designed study may founder because of poor outcome measurement or unacceptably high subject loss. The advantages of a well-designed trial apply equally to studies with short term outcomes and to those requiring long-term follow up. This paper therefore focuses on general methodological issues with a discussion, where appropriate, of the special considerations associated with long-term follow-up. This emphasis is motivated by the belief that a trial with methodological weaknesses is both a waste of resources and unethical. Anyone planning to undertake a randomized controlled trial should consult a more comprehensive text [1-4]. Here, some selected issues are highlighted with the choice of topics reflecting the experience and interests of the authors.

Humans↗

PubMed2004

Back schools in occupational health care: design of a randomized controlled trial and cost-effectiveness study.

OBJECTIVE: To describe the design of a randomized controlled trial (RCT), including a cost-effectiveness analysis, comparing high-intensity and low-intensity back schools with usual care in occupational health care. DESIGN: RCT and cost-effectiveness analysis. STUDY POPULATION: Employees sick-listed for a period of 3 to 6 weeks because of nonspecific low back pain. Interventions High-intensity back school treatment consists of a training program based on the principles of cognitive-behavioral therapy. Low-intensity back school treatment is comparable to the original Swedish Back School. Usual care is provided by the occupational physician according to the Dutch guidelines for the occupational health treatment of patients with low back pain. OUTCOME MEASURES: Primary outcome measures are return to work, pain intensity, functional status, and general improvement. Secondary outcome measures are kinesiophobia and pain coping. The cost-effectiveness analysis includes the direct and indirect costs. The outcome measures are assessed before randomization and 3, 6, and 12 months after randomization. CONCLUSION: RCTs of different methodological quality have been conducted to examine the effectiveness of back schools in occupational health care. The large variation in type, content, and intensity of back schools has led to conflicting evidence. Therefore, 2 different forms of back schools are compared. Moreover, this is the first RCT to include a cost-effectiveness analysis comparing low-intensity and high-intensity back schools with usual care in occupational health care.

Adolescent↗

PubMed1995

Prospective randomized controlled trial of a micronized flavonidic fraction to reduce bleeding after haemorrhoidectomy.

A prospective randomized controlled trial was carried out on the effects of Daflon 500 mg (a micronized flavonidic fraction containing diosmin 450 mg and hesperidin 50 mg) on bleeding after haemorrhoidectomy. In all, 228 consecutive patients with prolapsed irreducible piles were recruited. Elective haemorrhoidectomy was performed with a standardized diathermy excision method. Some 114 patients were randomized to receive Daflon 500 mg for 1 week after operation (group 1), and there were 114 controls (group 2). Postoperative analgesia and laxative prescription as well as hospital stay were otherwise the same. One patient (0.9 per cent) from group 1 and seven (6.1 per cent) from group 2 had postoperative bleeding (P = 0.03). All bleeding occurred from 6 to 15 days after haemorrhoidectomy. There were no side-effects from the use of Daflon 500 mg. The risk of secondary bleeding from haemorrhoidectomy is reduced with postoperative Daflon.

Adult↗

PubMed1998

Dietary omega-3 polyunsaturated fatty acids plus vitamin E restore immunodeficiency and prolong survival for severely ill patients with generalized malignancy: a randomized control trial.

BACKGROUND: The aim of the current prospective, randomized control study was to investigate the effect of dietary omega-3 polyunsaturated fatty acids plus vitamin E on the immune status and survival of well-nourished and malnourished patients with generalized malignancy. METHODS: Sixty patients with generalized solid tumors were randomized to receive dietary supplementation with either fish oil (18 g of omega-3 polyunsaturated fatty acids, PUFA) or placebo daily until death. Each group included 15 well-nourished and 15 malnourished patients. The authors measured total T cells, T-helper cells, T-suppressor cells, natural killer cells, and the synthesis of interleukin-1, interleukin-6, and tumor necrosis factor by peripheral blood mononuclear cells before and on Day 40 of fish oil supplementation. Karnofsky performance status, nutritional state, and survival were also estimated. RESULTS: The ratio of T-helper cells to T-suppressor cells was significantly lower in malnourished patients. Omega-3 PUFA had a considerable immunomodulating effect by increasing this ratio in the subgroup of malnourished patients. There were no significant differences in cytokine production among the various groups, except for a decrease in tumor necrosis factor production in malnourished cancer patients, which was restored by omega-3 fatty acids. The mean survival was significantly higher for the subgroup of well-nourished patients in both groups, whereas omega-3 fatty acids prolonged the survival of all the patients. CONCLUSIONS: Malnutrition appears to be an important predictor of survival for patients with end stage malignant disease. Omega-3 polyunsaturated fatty acids had a significant immunomodulating effect and seemed to prolong the survival of malnourished patients with generalized malignancy.

Adjuvants, Immunologic↗

PubMed2005

Attempted randomized controlled trial of pamidronate versus calcium and calcitriol supplements for management of steroid-induced osteoporosis in children and adolescents.

OBJECTIVES: To describe an attempted interventional trial for glucocorticoid-induced osteoporosis in children and adolescents and to discuss the reasons for trial failure to inform future interventional studies in this important group of patients. METHODS: Prospective randomized controlled trial comparing the effect of bisphosphonate therapy with calcium and vitamin D supplementation on bone mineral accrual is described. For non-trial patients, retrospective analysis of the effect of calcium and vitamin D supplementation combined with bisphosphonate treatment on bone mineral accrual. RESULTS: Only 12 patients were enrolled in the trial over 4 years. Bisphosphonate recipients (n = 5) had a mean annual percentage increase in lumbar spine bone mineral density of 8.76 +/- 5.2% compared to 6.6 +/- 4.0% in the calcium/vitamin-treated group (difference not significant). Mean annual change in lumbar spine areal bone mineral density in non-trial patients (n = 11) was 3.72 +/- 2.5%. CONCLUSION: Conducting a randomized controlled trial in this group of corticosteroid users is difficult, given the unpredictable nature of the underlying disease and intermittent need for steroid treatment. The trial failed through inadequate recruitment combined with discontinued interventions.

Adolescent↗

PubMed2005

Proactive case management of high-risk patients with type 2 diabetes mellitus by a clinical pharmacist: a randomized controlled trial.

OBJECTIVE: To evaluate the effect of case management by a clinical pharmacist on glycemic control and preventive measures in patients with type 2 diabetes mellitus. STUDY DESIGN: Randomized controlled trial in a university-affiliated primary care internal medicine clinic. METHODS: We recruited 80 patients with poorly controlled type 2 diabetes mellitus. A clinical pharmacist provided evaluation and modification of pharmacotherapy, self-management diabetes education, and reinforcement of diabetes complications screening processes through clinic visits and telephone follow-up. The main clinical outcome was hemoglobin A1C (HbA1C) level; process measures included HbA1C and low-density lipoprotein measurement, retinal examination, urine microalbumin testing (or use of angiotensin-converting enzyme inhibitors), and monofilament screening for diabetic neuropathy. RESULTS: Patients in the intervention and control groups were similar in age, sex, mean HbA1C levels (10.1% and 10.2%, respectively; P = .65), and current treatment regimens at baseline. Patients who received case management by the clinical pharmacist achieved greater reduction in HbA1C levels than those in the control group (2.1% vs 0.9%, P = .03). Three of the 5 process measures were conducted more frequently in the intervention group than the control group, including low-density lipoprotein measurement (100.0% vs 85.7%, P = .02), retinal examination (97.3% vs 74.3%), and monofilament foot screening (92.3% vs 62.9%). CONCLUSIONS: Proactive diabetes case management by a pharmacist substantially improved glycemic control and diabetes process-of-care measures. This approach, integrated with and based in the primary care setting, was an effective and efficient approach to improving care, especially for those with poor glycemic control at baseline.

Blood Glucose↗

PubMed2003

A randomized controlled trial to assess sunscreen application and beta carotene supplementation in the prevention of solar keratoses.

BACKGROUND: Solar keratoses (SKs) are among the strongest determinants of skin cancer, but little is known about the success of measures to control these common skin tumors. OBJECTIVE: To determine whether daily sunscreen application and/or beta carotene supplementation retards the rate of occurrence of SKs in adults in the medium term. DESIGN: Randomized controlled trial conducted between February 1992 and August 1996. SETTING: General community of the subtropical township of Nambour, Australia (latitude, 26 degrees south). PARTICIPANTS: A total of 1621 adults aged 25 to 74 years. Interventions Participants were randomized to daily use of sunscreen (application of a high-protection sunscreen to their head, neck, arms, and hands every morning) or application of sunscreen at their usual discretionary rate. They were also randomly assigned to take either one 30-mg tablet of beta carotene or one placebo tablet each day. MAIN OUTCOME MEASURE: Change in the prevalent number of SKs in the intervention group relative to change in the control group. RESULTS: The ratio of SK counts in 1994 relative to 1992 was lower in people randomized to daily sunscreen use (1.20; 95% confidence interval, 1.04-1.39) than in those randomized to discretionary sunscreen use (1.57; 95% confidence interval, 1.35-1.84). This 24% reduction is equivalent to the prevention of an average of 1 additional SK per person over that time. A reduction in the rate of change of SK prevalence was also seen in the sunscreen intervention group relative to the discretionary sunscreen group between 1994 and 1996, but it was not significant. No effect on the rate of change of prevalent SK counts was seen among those taking beta carotene supplements relative to those taking placebo tablets. CONCLUSIONS: Daily application of sunscreen retarded the rate of SK acquisition among adults in a subtropical environment, while a beta carotene supplementation of 30 mg/d had no influence on the occurrence of SKs.

Adult↗

PubMed1989

A randomized controlled trial of extra-amniotic ethinyloestradiol in ripening the cervix at term.

A double-blind randomized controlled trial investigated the use of extra-amniotic ethinyloestradiol for ripening the unfavourable cervix at term. Twenty-five primigravidae were treated with 150 mg ethinyloestradiol gel while 24 primigravidae were treated with gel alone. There was no statistical difference between the ethinyloestradiol and control groups in either mean change in Bishop score or the induction-to-delivery interval.

Adult↗

PubMed2000

Cisapride treatment for gastro-oesophageal reflux in children: a systematic review of randomized controlled trials.

The aim of the systematic review was to determine the effect of cisapride compared with placebo or other non-surgical therapies for the treatment of symptoms of gastro-oesophageal reflux in children. We searched MEDLINE, EMBASE, the Cochrane Controlled Trials Register, Science Citation Index and reference lists for randomized controlled trials which compared cisapride with placebo or other non-surgical therapy in children. We included only trials which reported reflux-related symptoms as an outcome, provided that cisapride was administered orally for at least I week. Seven trials (286 children in total) compared cisapride with placebo. Two trials reported good concealment of treatment allocation. The pooled odds ratio for the 'same or worse' symptoms was 0.34 (95% CI 0.10, 1.19). There was substantial heterogeneity between studies (P < 0.00001) and the funnel plot was asymmetrical. Adverse effects (mainly diarrhoea) were not significantly increased with cisapride (pooled odds ratio (OR) 1.80: 0.87, 3.70). The reflux index was significantly reduced in children treated with cisapride (weighted mean difference -6.49: -10.13, -2.85). One study (50 children) compared cisapride with gaviscon plus carobel: the OR for the 'same or worse' symptoms was 3.26 (0.93, 11.38). There was no clear evidence that cisapride reduced symptoms of gastro-oesophageal reflux. As smaller, poorer quality studies were biased in favour of a positive treatment effect, the pooled OR overestimated the potential benefits of cisapride. There was some evidence to suggest that gaviscon plus carobel may be a more effective option than cisapride.

Child↗

PubMed1997

Practical guidelines for independent assessment in randomized controlled trials (RCTs) of rehabilitation.

OBJECTIVE: To provide guidelines for conducting independent assessments in randomized controlled trials (RCTs) of rehabilitation. The article aims to assist those who plan to put independent assessment into practice and to be an introduction for those who are new to independent assessment. ISSUES: Possible causes of unblinding to group allocation are discussed, such as unblinding by other people, the environment, patients and assessors themselves. Other issues discussed in this paper are bias during assessment and monitoring levels of unblinding. CONCLUSION: The importance of monitoring levels of unblinding is stressed. Although it may not be possible to always keep an assessor blind in RCTs of rehabilitation, we should strive for perfection. It is therefore advocated that levels of unblinding should be reported.

Bias↗

PubMed1998

Time to publication as full reports of abstracts of randomized controlled trials in cystic fibrosis.

OBJECTIVES: To determine 1) what proportion of abstracts of randomized controlled trials (RCTs) presented at international conferences on cystic fibrosis (CF) are published as full reports, 2) time to publication, and 3) factors that might delay or prevent publication. METHODS: At the end of 1995, the Cochrane CF Group's register of RCTs contained 199 abstracts describing 180 RCTs. Abstracts were identified by handsearching 44 abstract books of three international CF conferences over a 30-year period. We searched the register for subsequent full reports of these RCTs and used survival analysis to investigate time to publication. Using the log-rank test, we examined 1) whether there is a difference in time to publication between reports where the investigators concluded that the test treatment was as effective as or better than the control treatment, and reports where it was not, and 2) whether there is a difference in time to publication according to sample size. RESULTS: Thirty-two percent of the 178 abstracts analyzed were subsequently published in full. Survival analysis indicated that the proportions published before 12 months, 2 years, and 5 years were 8.1%, 29%, and 40% respectively. No difference in time to publication was identified when the abstracts were stratified according to conclusions or sample size; no significant association (P > 0.05) existed between time to publication and both sample size and conclusions together. CONCLUSION: Only a small proportion of abstracts of RCTs presented at international conferences on CF are followed by full publication, and usually only after several years. Therefore, many potentially valuable studies do not reach a wide audience. However, we found no consistent factors which might delay or prevent publication.

Abstracting and Indexing↗

PubMed2002

Issues in conducting randomized controlled trials of health services research interventions in nonacademic practice settings: the case of retail pharmacies.

OBJECTIVE: To describe unexpected challenges and strategies to overcome them when conducting randomized controlled trials (RCT) of health services research interventions in retail pharmacies. STUDY SETTING: Thirty-six retail drug stores in Indianapolis. STUDY DESIGN: We conducted an RCT to evaluate the effectiveness of an intervention to increase pharmacists' involvement in caring for customers. We describe: (1) our RCT as originally designed, (2) unexpected challenges we faced; and (3) how we resolved those challenges. DATA COLLECTION/EXTRACTION METHODS: Randomized controlled trial. PRINCIPAL FINDINGS: Major modifications in research design were necessitated by factors such as corporate restructuring, heightened sensitivity to patient confidentiality, and difficulties altering employees' behavior. We overcame these barriers by conducting research that is consistent with corporate goals, involving appropriate corporate administrators and technical personnel early in the process, and being flexible. CONCLUSIONS: Health services researchers should conduct RCTs in a variety of non-academic practice settings to increase generalizability and better reflect the true impact of interventions. Pragmatic problems, although significant, can be successfully overcome.

Adolescent↗

PubMed2004

Moderate-to-severe pain after knee arthroscopy is relieved by intraarticular saline: a randomized controlled trial.

UNLABELLED: We have previously studied intraarticular (IA) analgesics compared with saline 10 mL in 2 randomized clinical trials. The patients who were given IA saline experienced rapid pain relief. Hypothetically, saline may produce a local analgesic effect by cooling or by diluting IA algogenic substances. This randomized double-blind study compared the analgesic effect of IA saline 10 mL with saline 1 mL, which should be a pure placebo. A soft catheter was left IA in 79 patients. We included 60 patients who developed moderate-to-severe pain within 1 h after knee arthroscopy under general anesthesia. A randomized, double-blind controlled comparison of IA saline 10 mL with saline 1 mL followed. Outcome measures were pain intensity, pain relief, and analgesic consumption. Within 1 h pain intensity decreased in both groups from approximately 50 to approximately 27 on a 0-100 mm visual analog scale. Pain intensity remained low and other pain outcome measures were similar during the 36-h observation period. The patients experienced equally good pain relief after IA injection of saline 10 mL and 1 mL. Our finding of a major placebo effect may have implications for the interpretation of previously published placebo-controlled IA analgesia studies. IMPLICATIONS: In a randomized controlled trial we showed that pain after knee arthroscopy is modest and short-lived and can successfully be treated with intraarticular saline as placebo.

Adult↗

PubMed2006

"Hitting" voices of schizophrenia patients may lastingly reduce persistent auditory hallucinations and their burden: 18-month outcome of a randomized controlled trial.

OBJECTIVE: This study aimed to investigate the outcome of an 18-month randomized controlled trial (RCT) on subjective burden and psychopathology of patients suffering from schizophrenia. METHOD: An RCT was used to compare hallucination-focused integrative treatment (HIT) and routine treatment (RT) in schizophrenia patients who persistently hear voices. We performed an intent-to-treat analysis on each of the 63 patients who were assessed at baseline, 9, and 18 months. On each of the 3 occasions, the differential effects of the treatment conditions were tested repeatedly. Sex, age, education, and illness (hallucination) duration were used as covariates. RESULTS: Patients in the experimental group retained improvements over time. Improvements in hallucinations, distress, and negative content of voices remained significant at the 5% level. CONCLUSION: HIT seems to be an effective treatment strategy with long-lasting effects for treatment-refractory voice-hearing patients.

Adaptation, Psychological↗

PubMed2005

Can the randomized controlled trial literature generalize to nonrandomized patients?

To determine the extent to which published randomized controlled trials (RCTs) of psychotherapy can be generalized to a sample of outpatients, the authors matched information obtained from charts of patients who had been screened out of RCTs to inclusion and exclusion criteria from published RCT studies. Most of the patients in the sample who had primary diagnoses represented in the RCT literature were judged eligible for at least 1 RCT. However, many patients in the sample with substance use disorders or social anxiety disorder were not eligible for at least 2 RCTs. Common reasons that patients did not match with at least 2 published RCTs for psychotherapy included (a) patients were in partial remission, (b) patients failed to meet minimum severity or duration criteria, (c) patients were being treated with antidepressant medication, and (d) the disorder being studied was not primary (mostly for social anxiety patients). The implications of these findings for future research and clinical practice are discussed.

Adult↗

PubMed2003

Bleeding patterns after immediate vs. conventional oral contraceptive initiation: a randomized, controlled trial.

OBJECTIVE: To compare bleeding patterns after immediate vs. conventional oral contraceptive (OC) initiation. DESIGN: Randomized controlled trial. SETTING: University-based clinic. PATIENT(S): One hundred thirteen women initiating combination OCs. INTERVENTION(S): Participants received a 4-month supply of a monophasic 35-microg ethinyl E(2) (EE) OC and a bleeding diary, were randomized to immediate or conventional OC start, underwent monthly telephone follow-up, and after 90 days returned the diary and completed an exit interview. MAIN OUTCOME MEASURE(S): Total number of bleeding-spotting days, using the World Health Organization 90-day reference period method. Comparisons were made by trial assignment (immediate vs. conventional) and cycle day of OC initiation (day 8+ vs. days 1-7). RESULT(S): There was no significant difference in the number of bleeding-spotting days (mean difference: -0.5 days; 95% CI: -3.4 to 2.3) or any other bleeding parameter between the immediate and conventional starters, or days 1-7 and day 8+ starters. CONCLUSION(S): Immediate start of OCs does not induce bleeding patterns different from conventional starting regimens. Concern about adverse bleeding patterns should not be considered a justification for instructing women to wait until menses before starting OCs.

Adult↗

PubMed2004

Covariate adjustment in randomized controlled trials with dichotomous outcomes increases statistical power and reduces sample size requirements.

OBJECTIVE: Randomized controlled trials (RCTs) with dichotomous outcomes may be analyzed with or without adjustment for baseline characteristics (covariates). We studied type I error, power, and potential reduction in sample size with several covariate adjustment strategies. STUDY DESIGN AND SETTING: Logistic regression analysis was applied to simulated data sets (n=360) with different treatment effects, covariate effects, outcome incidences, and covariate prevalences. Treatment effects were estimated with or without adjustment for a single dichotomous covariate. Strategies included always adjusting for the covariate ("prespecified"), or only when the covariate was predictive or imbalanced. RESULTS: We found that the type I error was generally at the nominal level. The power was highest with prespecified adjustment. The potential reduction in sample size was higher with stronger covariate effects (from 3 to 46%, at 50% outcome incidence and covariate prevalence) and independent of the treatment effect. At lower outcome incidences and/or covariate prevalences, the reduction was lower. CONCLUSION: We conclude that adjustment for a predictive baseline characteristic may lead to a potentially important increase in power of analyses of treatment effect. Adjusted analysis should, hence, be considered more often for RCTs with dichotomous outcomes.

Data Interpretation, Statistical↗

PubMed2000

A randomized controlled trial of intracameral lidocaine during phacoemulsification under topical anesthesia.

OBJECTIVE: To test the hypothesis that adjunctive intracameral 1% lidocaine reduces intraoperative pain during phacoemulsification using topical anesthesia. DESIGN: Prospective, double-masked, randomized, controlled trial. PARTICIPANTS: A total of 200 patients undergoing routine phacoemulsification under topical 1% tetracaine were studied. INTERVENTION: Randomization to 0.5 ml intracameral, unpreserved, epinephrine-free 1% lidocaine or placebo was conducted. MAIN OUTCOME MEASURE: Intraoperative pain was quantified by the patients using a 0-10 visual analog pain scale. RESULTS: Intraoperative pain scores (+/- standard deviation) for the lidocaine and control groups were 1.29 +/-1.24 and 1.44 +/- 1.33, respectively (P > 0.35). CONCLUSIONS: In a rigorously double-masked, prospective, randomized, controlled trial there was no significant reduction in intraoperative pain when intracameral 1% lidocaine was used during phacoemulsification under topical anesthesia.

Adult↗