Understanding controlled trials. Randomisation methods: concealment

Clinical trial of a home safety toolkit for Alzheimer's disease

This randomized clinical trial tested a new self-directed educational intervention to improve caregiver competence to create a safer home environment for persons with dementia living in the community. The sample included 108 patient/caregiver dyads: the intervention group (n = 60) received the Home Safety Toolkit (HST), including a new booklet based on health literacy principles, and sample safety items to enhance self-efficacy to make home safety modifications. The control group (n = 48) received customary care. Participants completed measures at baseline and at twelve-week follow-up. Multivariate Analysis of Covariance (MANCOVA) was used to test for significant group differences. All caregiver outcome variables improved in the intervention group more than in the control. Home safety was significant at P ≤ 0.001, caregiver strain at P ≤ 0.001, and caregiver self-efficacy at P = 0.002. Similarly, the care receiver outcome of risky behaviors and accidents was lower in the intervention group (P ≤ 0.001). The self-directed use of this Home Safety Toolkit activated the primary family caregiver to make the home safer for the person with dementia of Alzheimer's type (DAT) or related disorder. Improving the competence of informal caregivers is especially important for patients with DAT in light of all stakeholders reliance on their unpaid care.

How to appraise a randomized controlled trial

Critical appraisal is an essential skill for evidence-based practitioners. It involves the systematic examination of research in order to assess its trustworthiness and relevance to specific situations. This article gives an overview on how to approach critical appraisal of randomized controlled trials.

Randomized controlled trial of percutaneous versus transcutaneous posterior tibial nerve stimulation in faecal incontinence

BACKGROUND

Percutaneous, transcutaneous and sham transcutaneous posterior tibial nerve stimulation was compared in a prospective blinded randomized placebo-controlled trial.

METHODS

Patients who had failed conservative treatment for faecal incontinence were randomized to one of three groups: group 1, percutaneous; group 2, transcutaneous; group 3, sham transcutaneous. Patients in groups 1 and 2 received 30-min sessions of posterior tibial nerve stimulation twice weekly for 6 weeks. In group 3, transcutaneous electrodes were placed in position but no stimulation was delivered. Symptoms were measured at baseline and after 6 weeks using a bowel habit diary and St Mark's continence score. Response to treatment was defined as a reduction of at least 50 per cent in weekly episodes of faecal incontinence compared with baseline.

RESULTS

Thirty patients (28 women) were enrolled. Nine of 11 patients in group 1, five of 11 in group 2 and one of eight in group 3 had a reduction of at least 50 per cent in weekly episodes of faecal incontinence at the end of the 6-week study phase (P = 0·035). Patients undergoing percutaneous nerve stimulation had a greater reduction in the number of incontinence episodes and were able to defer defaecation for a longer interval than those undergoing transcutaneous and sham stimulation. These improvements were maintained over a 6-month follow-up period.

CONCLUSION

Posterior tibial nerve stimulation has short-term benefits in treating faecal incontinence. Percutaneous therapy appears to have superior efficacy to stimulation applied by the transcutaneous route.

REGISTRATION NUMBER

NCT00530933 (http://www.clinicaltrials.gov).

Guidelines for the Design and Conduct of Clinical Studies in Knee Articular Cartilage Repair: International Cartilage Repair Society Recommendations Based on Current Scientific Evidence and Standards of Clinical Care

OBJECTIVE

To summarize current clinical research practice and develop methodological standards for objective scientific evaluation of knee cartilage repair procedures and products.

DESIGN

A comprehensive literature review was performed of high-level original studies providing information relevant for the design of clinical studies on articular cartilage repair in the knee. Analysis of cartilage repair publications and synopses of ongoing trials were used to identify important criteria for the design, reporting, and interpretation of studies in this field.

RESULTS

Current literature reflects the methodological limitations of the scientific evidence available for articular cartilage repair. However, clinical trial databases of ongoing trials document a trend suggesting improved study designs and clinical evaluation methodology. Based on the current scientific information and standards of clinical care, detailed methodological recommendations were developed for the statistical study design, patient recruitment, control group considerations, study endpoint definition, documentation of results, use of validated patient-reported outcome instruments, and inclusion and exclusion criteria for the design and conduct of scientifically sound cartilage repair study protocols. A consensus statement among the International Cartilage Repair Society (ICRS) and contributing authors experienced in clinical trial design and implementation was achieved.

CONCLUSIONS

High-quality clinical research methodology is critical for the optimal evaluation of current and new cartilage repair technologies. In addition to generally applicable principles for orthopedic study design, specific criteria and considerations apply to cartilage repair studies. Systematic application of these criteria and considerations can facilitate study designs that are scientifically rigorous, ethical, practical, and appropriate for the question(s) being addressed in any given cartilage repair research project.

Generalized method for adaptive randomization in clinical trials

A flexible, generalized method of treatment allocation is proposed. The method uses a set of controlling parameters that enables the generic algorithm to produce a family of possible outcomes ranging from simple randomization to deterministic allocation. The method controls balance at stratum level, stratification level and overall without detriment to the predictability of the method. The paper lists the desirable characteristics of allocation methods and shows that the proposed method fulfils the majority and is easy to use in the clinical context, once the coding has been established. An explanation of the method for 2, 3 and 4 treatment group allocations is given. Simulations demonstrate the flexibility of the method.

Improving outcomes for COPD patients with mild-to-moderate anxiety and depression: A systematic review of cognitive behavioural therapy

PURPOSE

Anxiety and depression are highly prevalent in patients with chronic obstructive pulmonary disease (COPD) and are associated with lower levels of self-efficacy, impaired health status, poorer treatment outcomes and reduced survival following emergency admission. Cognitive behavioural therapy (CBT) may be effective for treating anxiety and depression in COPD patients but evidence for this is uncertain.

METHODS

A systematic review of controlled trials that evaluated the effectiveness of CBT for treating mild-to-moderate anxiety or depression in adults with clinically stable COPD. Ovid electronic bibliographic databases were searched from inception to May 2006; all content held by the Cochrane Library Issue 3, 2006 was also searched.

RESULTS

One small randomized controlled trial (RCT) of moderate quality showed that CBT, when given with exercise training and education, was associated with large and significant treatment effects for both anxiety (-1.39 (95% CIs -2.19, -0.59)) and depression (-0.86 (95% CIs -1.61, -0.11)). Additionally, a larger RCT of higher quality demonstrated that CBT, when given with exercise and education, was associated with large and significant treatment effects for depression (-0.76 (95% CIs -1.34, -0.17)), but not for anxiety. No other included study reported significant reductions in either anxiety or depression in COPD patients given CBT.

CONCLUSION

There is only limited evidence that CBT, when used with exercise and education, can contribute to significant reductions in anxiety and depression in COPD patients. There is scope for a well-powered RCT to evaluate the effectiveness and acceptability of CBT among this patient population.

Enhanced recovery in colorectal resections: a systematic review and meta-analysis

OBJECTIVE

The study aimed to produce a comprehensive up-to-date meta-analysis exploring the safety and efficacy of enhanced recovery (ER) programmes after colorectal resection.

METHOD

Key-word and MESH-heading searches of MEDLINE, EMBASE and the Cochrane Databases from 1966 to February 2007 were used to identify all available randomized and clinical controlled studies. Two independent reviewers assessed studies for inclusion and exclusion based on methodological quality criteria prior to undertaking data extraction. Summary estimates of treatment effects using a fixed effect model were produced with RevMan 1.0.2, using weighted means for length-of-stay data and relative risks of morbidity, mortality and readmission rates.

RESULTS

Analysis of four papers including 376 patients demonstrated primary and total length-of-stays (primary + readmission length-of-stay) to be significantly reduced (P < 0.001) with ER programmes [weighted mean differences of -3.64 days (95% confidence interval, 95% CI -4.98 to -2.29) and -3.75 days (95% CI-5.11 to -2.40)]. Analysis of controlled clinical trial data showed morbidity rates to be reduced and readmission rates increased. These trends were not seen amongst the randomized controlled trial data. There were no differences in mortality rates.

CONCLUSION

Enhanced recovery programmes after colorectal resections reduce length-of-stay and may reduce 30 days morbidity and increase 30 days readmission without increasing mortality.

The quality of trials in operative surgery

OBJECTIVE

This study aimed to assess the reported quality of trials in operative surgery.

SUMMARY BACKGROUND DATA

Randomized controlled trials (RCTs) in operative surgery have previously been criticized for using weak methodology despite no evidence to suggest their quality is any different from nonsurgical trials.

STUDY DESIGN

All surgical RCTs published in the British Medical Journal, the Journal of the American Medical Association, The Lancet, and the New England Journal of Medicine between 1998 and 2004 were identified. The adequacy of the reported methodology used to perform the randomization, power calculation, and recruitment was assessed for each trial using predefined criteria. The results from the surgical trials were compared with a randomly selected control group of nonsurgical RCTs, which were matched for journal and year of publication.

RESULTS

Sixty-six surgical RCTs were identified. Adequate reporting of randomization sequence generation was seen in 42% (n = 28) of surgical trials and 30% (n = 20) of nonsurgical trials, and adequate allocation concealment was recorded in 46% (n = 30) and 47% (n = 31), respectively. When combining these 2 interrelated steps of randomization, only 26% (n = 17) of surgical trials and 23% (n = 15) of nonsurgical trials reported both adequately. Adequate recruitment was recorded in 52% (n = 33 of 63) surgical and 55% (n = 33 of 60) nonsurgical trials, with approximately a quarter (n = 17 and n = 16, respectively) of the trials in both the surgical and nonsurgical categories reporting an adequate power calculation.

CONCLUSIONS

There was no evidence that the reported quality of surgical trials was different to nonsurgical trials. However, approximately half or less of all the trials reviewed reported adequate methodology.

Influence of prior assignment on refusal rates in a trial of supplemental oxygen for retinopathy of prematurity

Investigators aware of prior treatment assignments may deliberately or subliminally influence rates of subsequent consent in randomised trials, thus introducing the possibility of bias. As a trial of Supplemental Therapeutic Oxygen for Prethreshold Retinopathy of Prematurity (STOP-ROP) was not masked to health professionals other than ophthalmologists, this possibility was evaluated by comparing the incidence of refusal to participate in relation to the previous assignment. Over 5 years, the STOP-ROP trial enrolled 649 infants, while 394 eligible subjects refused. Enrolled infants were assigned to supplemental oxygen or control groups at 30 centres including 71 hospitals, and stratified into two severity strata of their retinopathy of prematurity. We studied whether the assignment of the previously enrolled infant to either the supplemental arm or the control arm of the study affected the incidence of refusal to participate in the study by the next eligible infant. We also evaluated the possibility that refusal based on the preceding assignment could have influenced either the baseline balance of eye severity and pulmonary status between the two arms of the study or the final outcome of the randomised trial. There was a significantly higher incidence of refusal if the prior enrollee had been assigned to the supplemental oxygen group (44%) as compared with the control group (34%, P = 0.004). This effect from the prior assignment was larger in the later half of the study. Irrespective of the prior enrollee's assignment, refusal was more likely for more mature infants and those with milder baseline disease. Selection bias did not influence the ophthalmic or pulmonary findings at baseline, or the study outcomes. In incompletely masked studies, monitoring the distribution of refusers in relation to the previous assignment can reveal selection bias. Despite evidence of unequal refusal rates, the results of the STOP-ROP trial were not affected.

Understanding randomised controlled trials

The hierarchy of evidence in assessing the effectiveness of interventions or treatments is explained, and the gold standard for evaluating the effectiveness of interventions, the randomised controlled trial, is discussed. Issues that need to be considered during the critical appraisal of randomised controlled trials, such as assessing the validity of trial methodology and the magnitude and precision of the treatment effect, and deciding on the applicability of research results, are discussed. Important terminologies such as randomisation, allocation concealment, blinding, intention to treat, p values, and confidence intervals are explained.

Randomized controlled trials of socially complex nursing interventions: creating bias and unreliability?

BACKGROUND

The randomized controlled trial is viewed by many researchers as the 'gold standard' research design. It is used increasingly to evaluate the effectiveness of socially complex activities such as nursing interventions. This use is seen by many commentators as problematic, while others are concerned about the quality of many published trial reports. One area of concern is that of intervention bias: the impact that a sentient intervention, such as a nursing one, may have consciously or unconsciously on study outcomes. This paper reports on an analysis of intervention definitions and possible intervention bias in 47 reports of randomized controlled trials of nursing interventions published in 2000 or 2001.

AIMS

This study evaluates four characteristics of the included reports: intervention sample size, intervention definition, involvement of intervention nurses in other aspects of the trial, and the claimed generalizability of results.

METHODS

Reports of randomized controlled trials published in 2000 or 2001 were identified. Full-text versions of 47 papers were obtained and information about the four characteristics was extracted and analysed.

RESULTS

Problems relating to possible intervention bias were identified in each of the papers. Inadequate intervention definition was the commonest problem, leading to difficulties in calculating the 'intervention dose' and in replicating or generalizing from the studies.

DISCUSSION

None of the included studies met the requirements of the Consolidated Standards of Reporting Trials. Four types of intervention bias were identified, and their possible implications for the reporting of trials of nursing interventions are discussed. This was a small-scale study, limited by time and resources. Its results are suggestive of a major problem of intervention bias but larger-scale investigations are necessary to quantify its extent.

CONCLUSIONS

Intervention bias is potentially a problem in randomized controlled trials. Lack of detail about interventions in published papers could be corrected by stricter adherence to guidelines such as the Consolidated Standards of Reporting Trials, but this will not correct the underlying problem of inadequate study design that appears to be widespread in randomized controlled trials of nursing interventions.

Occlusion: Reflections on science and clinical reality

The last 50 years have seen progress in emphasizing scientific evidence as a basis for dental practice, including occlusal therapy. Although a proper understanding of the contributory role of occlusion to temporomandibular disorders should not be minimized, the importance of occlusion in other areas of dental education and practice should not be overlooked. The primary objective of this article is to discuss the nature of this problem as it relates to the duality of science and clinical reality in the evidence-based paradigm, information transfer, quality of evidence, clinical trials, and clinical aspects of occlusion. Some suggested solutions for the problem and thoughts on past and future perspectives of occlusion are expressed in context of inquiry.

When can a clinical trial be called 'randomized'?

It is widely recognized that, in the context of the evaluation of medical interventions, randomized clinical trials constitute the gold standard. This is because randomization tends to balance both measured and unmeasured baseline characteristics, allows for masking, and provides a basis for inference. It is understandable, then, that investigators would wish to utilize this methodology whenever it is feasible to do so. Unfortunately, some studies are labeled as randomized when in fact they are not. These studies then receive more credibility, and influence medical practice, more than they deserve to. After reviewing the benefits of randomization, paying particular attention to the specific aspects of randomization that confer each benefit, we will explore the issue of what constitutes a randomized study.

Quality of RCTs in periodontology--a systematic review

Randomization, concealment of treatment allocation, blinding, and patient follow-up are key quality components of randomized controlled trials (RCTs). The objective of this study was to assess the quality of RCTs in periodontology using these evidence-based components. Following a detailed search, screening and quality assessments of RCTs were conducted in duplicate and independently. The results showed that although 91% of trials were described as randomised, adequate methods for randomization and allocation concealment were found in 17% and 7% of studies, respectively. Blinding was adequate for the caregiver in 17% and for the examiner in 55% of studies. A clear accounting of all participants was present in 56% of reports. This rigorous systematic review revealed that the quality of RCTs in periodontology, judged by their publications, frequently does not meet recommended standards. If this quality is reflected in actual study conduct, fundamental errors could have a significant impact on the outcomes of these trials.

Oral bisphosphonates and upper gastrointestinal tract problems: what is the evidence?

OBJECTIVE

To review and evaluate the evidence regarding possible associations of bisphosphonate use with upper gastrointestinal (GI) tract adverse events (AEs).

METHODS

We reviewed and summarized published information and abstracts regarding upper GI tract safety and tolerability of bisphosphonates, including laboratory and animal studies, epidemiological (observational) studies, endoscopy studies, and randomized controlled trials (RCTs). The evidence was summarized by using the principles of evidence-based medicine, giving the greatest credence to high-quality RCTs.

RESULTS

Clinical reports of esophagitis associated with bisphosphonate use appear to have declined in frequency once the importance of proper administration was explained to physicians after early reports of complications. Conflicting results have been reported in endoscopy studies; some reported no significant increase in upper GI tract lesions, whereas others reported a higher incidence of gastric (but not esophageal) lesions among patients taking oral bisphosphonates. Endoscopy studies that reported differences were of short duration (2 weeks) and were not of double-blind design. Results from large RCTs involving thousands of participants detected no increase in upper GI tract AEs among individuals treated with bisphosphonates. Other studies of patients who discontinued taking bisphosphonates and were randomized to blinded re-treatment with either a bisphosphonate or placebo show that most patients (>85%) were able to continue treatment, with no difference in AEs between the bisphosphonate and placebo groups.

CONCLUSIONS

The highest level of evidence, RCTs, suggests little or no increase in risk of upper GI tract problems if bisphosphonates are administered properly. Upper GI tract symptoms are common among patients with osteoporosis. The evidence suggests that many upper GI tract AEs reported during therapy with bisphosphonates may reflect a high background incidence of upper GI tract complaints and an increased sensitivity to detection rather than a causal relationship to therapy.

Teaching evidence-based complementary and alternative medicine: 4. Appraising the evidence for papers on therapy

Practicing evidence-based complementary and alternative medicine (CAM) requires practitioners to develop an ability to appraise the quality of published studies addressing questions related to their clinical practice. This paper describes a process by which CAM practitioners can determine the validity of studies evaluating therapeutic interventions. The process requires asking two broad questions: (1). Do the treatment and control group begin with the same prognosis? and (2). Do the treatment and control group remain the same with respect to important prognostic factors? Answering these questions requires determining whether studies used effective randomization, preserved randomization through intention-to-treat analyses, used blinding, and had adequate follow-up of trial participants.

Searching the health care literature efficiently: from clinical decision-making to continuing education

Searching the health care literature is an activity in which infection control professionals must routinely engage to seek evidence-based answers to specific practice questions and to stay abreast of developments in the field. Without the appropriate tools, the tremendous volume of clinical literature makes both of these daunting tasks. In this article, we illustrate techniques for searching MEDLINE efficiently, both as a means of answering particular clinical questions and for generating periodic updates on topics of general interest. With use of a specific example relevant to infection control, we demonstrate the identification of appropriate Medical Subject Headings terms that capture a given question or topic and the development of effective searches with use of these terms. We also touch on the advantages of targeting systematic reviews and meta-analyses in searching for evidence and staying abreast of the literature in general.

Allocation concealment in randomised trials: defending against deciphering

Proper randomisation rests on adequate allocation concealment. An allocation concealment process keeps clinicians and participants unaware of upcoming assignments. Without it, even properly developed random allocation sequences can be subverted. Within this concealment process, the crucial unbiased nature of randomised controlled trials collides with their most vexing implementation problems. Proper allocation concealment frequently frustrates clinical inclinations, which annoys those who do the trials. Randomised controlled trials are anathema to clinicians. Many involved with trials will be tempted to decipher assignments, which subverts randomisation. For some implementing a trial, deciphering the allocation scheme might frequently become too great an intellectual challenge to resist. Whether their motives indicate innocent or pernicious intents, such tampering undermines the validity of a trial. Indeed, inadequate allocation concealment leads to exaggerated estimates of treatment effect, on average, but with scope for bias in either direction. Trial investigators will be crafty in any potential efforts to decipher the allocation sequence, so trial designers must be just as clever in their design efforts to prevent deciphering. Investigators must effectively immunise trials against selection and confounding biases with proper allocation concealment. Furthermore, investigators should report baseline comparisons on important prognostic variables. Hypothesis tests of baseline characteristics, however, are superfluous and could be harmful if they lead investigators to suppress reporting any baseline imbalances.

Splinting or surgery for carpal tunnel syndrome? Design of a randomized controlled trial [ISRCTN18853827]

BACKGROUND

Carpal tunnel syndrome is a common disorder, which can be treated with surgery or conservative options. However, there is insufficient evidence and no consensus among physicians with regard to the preferred treatment for carpal tunnel syndrome. Therefore, a randomized controlled trial is conducted to compare the short- and long-term efficacy of surgery and splinting in patients with carpal tunnel syndrome. An attempt is also made to avoid the (methodological) limitations encountered in earlier trials on the efficacy of various treatment options for carpal tunnel syndrome.

METHODS

Patients of 18 years and older, with clinically and electrophysiologically confirmed idiopathic carpal tunnel syndrome, are recruited by neurologists in 13 hospitals. Patients included in the study are randomly allocated to either open carpal tunnel release or wrist splinting during the night for at least 6 weeks. The primary outcomes are general improvement, waking up at night and severity of symptoms (main complaint, night and daytime pain, paraesthesia and hypoesthesia). Outcomes are assessed up to 18 months after randomization.

Preventing fractures in postmenopausal women with osteoporosis. A review of recent controlled trials of antiresorptive agents

The evidence from randomised, controlled trials of the ability of antiresorptive treatments to reduce the risk of fractures in postmenopausal women with osteoporosis is reviewed and summarised. The aminobisphosphonates, alendronic acid and risedronic acid, and the selective estrogen receptor modulator raloxifene have all been shown to reduce the incidence of radiographic vertebral fractures. Only alendronic acid and risedronic acid have been shown to reduce the incidence of non-spine fractures in women with postmenopausal osteoporosis. There is evidence of antifracture efficacy for calcium plus vitamin D, primarily in a nursing home setting or in people with low intakes of these nutrients. Furthermore, since both the placebo and active treatment groups received calcium and vitamin D in most controlled trials of antiresorptive agents, it appears that the other agents provide benefits beyond those of calcium and vitamin D alone. There is insufficient published evidence from randomised controlled trials to convincingly support the antifracture efficacy of other agents, including calcitonin, estrogen and etidronic acid, at this time. Data from observational studies suggest, however, that estrogen and etidronic acid may have antifracture efficacy in this population.