A checklist to evaluate a report of a nonpharmacological trial (CLEAR NPT) was developed using consensus

BACKGROUND AND OBJECTIVE: To develop a checklist of items measuring the quality of reports of randomized clinical trials (RCTs) assessing nonpharmacological treatments (NPTs). STUDY DESIGN AND SETTING: The Delphi consensus method was used to select and reduce the number of items in the checklist. A total of 154 individuals were invited to participate: epidemiologists and statisticians involved in the field of methodology of RCTs (n = 55), members of the Cochrane Collaboration (n = 41), and clinicians involved in planning NPT clinical trials (n = 58). Participants ranked on a 10-point Likert scale whether an item should be included in the checklist. RESULTS: Fifty-five experts (36%) participated in the survey. They were experienced in systematic reviews (68% were involved in the Cochrane Collaboration) and in planning RCTs (76%). Three rounds of the Delphi method were conducted to achieve consensus. The final checklist contains 10 items and 5 subitems, with items related to the standardization of the intervention, care provider influence, and additional measures to minimize the potential bias from lack of blinding of participants, care providers, and outcome assessors. CONCLUSIONS: This tool can be used to critically appraise the medical literature, design NPT studies, and assess the quality of trial reports included in systematic reviews.     

An observational study found that authors of randomized controlled trials frequently use concealment of randomization and blinding, despite the failure to report these methods

BACKGROUND AND OBJECTIVE: Readers of randomized controlled trials (RCTs) commonly assume that what was not reported did not occur. We undertook an observational study to determine whether concealment of randomization or blinding was used in RCTs that failed to report these bias-reducing strategies. METHODS: We recorded the reporting of concealment of randomization and blinding in 105 RCTs. We subsequently contacted the authors and determined if they had used these methodological safeguards. RESULTS: We successfully obtained data from 98 authors. The authors in the full-text publications of these 98 RCTs failed to report the presence or absence of concealment of randomization in 55%, and the blinding status of participants in 26%, health care providers in 64%, data collectors in 84%, outcome assessors in 83%, and data analysts in 96%. In direct contact, authors frequently reported concealing randomization (96%; 95% confidence interval CI=87-100%), blinding participants (20%; 95% CI=7-41%), blinding health care providers (65%; 95% CI=52-77%), blinding data collectors (65%; 95% CI=53-75%), blinding outcome assessors (79%; 95% CI=69-87%), and blinding data analysts (50%; 95% CI=40-60%), despite not reporting the use of these methodological safeguards in their publications. CONCLUSIONS: Readers should not assume that bias-reducing procedures not reported in an RCT did not occur.     

Participant blinding and gastrointestinal illness in a randomized, controlled trial of an in-home drinking water intervention.

We conducted a randomized, triple-blinded home drinking water intervention trial to determine if a large study could be undertaken while successfully blinding participants. Households were randomized 50:50 to use externally identical active or sham treatment devices. We measured the effectiveness of blinding of participants by using a published blinding index in which values >0.5 indicate successful blinding. The principal health outcome measured was "highly credible gastrointestinal illness" (HCGI). Participants (n=236) from 77 households were successfully blinded to their treatment assignment. At the end of the study, the blinding index was 0.64 (95% confidence interval 0.51-0.78). There were 103 episodes of HCGI during 10,790 person-days at risk in the sham group and 82 episodes during 11,380 person-days at risk in the active treatment group. The incidence rate ratio of disease (adjusted for the clustered sampling) was 1.32 (95% CI 0.75, 2.33) and the attributable risk was 0.24 (95% CI -0.33, 0.57). These data confirm that participants can be successfully blinded to treatment group assignment during a randomized trial of an in-home drinking water intervention.     

Blinded trials taken to the test: an analysis of randomized clinical trials that report tests for the success of blinding

BACKGROUND: Blinding can reduce bias in randomized clinical trials, but blinding procedures may be unsuccessful. Our aim was to assess how often randomized clinical trials test the success of blinding, the methods involved and how often blinding is reported as being successful. METHODS: We analysed a random sample of blinded randomized clinical trials indexed in the The Cochrane Central Register of Controlled Trials and published in 2001. We identified 1599 blinded trials, and noted if they had conducted any test for the success of blinding. We also selected 200 trials randomly that did not report any such test, and sent a questionnaire to the corresponding authors asking them if they had conducted any tests. RESULTS: Thirty-one out of 1599 trials (2%) reported tests for the success of blinding. Test methods varied, and reporting was generally incomplete. Blinding was considered successful in 14 out of the 31 trials (45%) and unclear in 10 (32%). Of the seven trials (23%) reporting unsuccessful blinding the risk of a biased trial result was either not addressed or was discounted in six cases. We received 130 questionnaires from trial authors (65%) of which 15 (12%) informed that they had conducted, but not published, tests. CONCLUSIONS: Blinding is rarely tested. Test methods vary, and the reporting of tests, and test results, is incomplete. There is a considerable methodological uncertainty how best to assess blinding, and an urgent need for improved methodology and improved reporting.     

A theoretical analysis showed that blinding cannot eliminate potential for bias associated with beliefs about allocation in randomized clinical trials

ObjectivesTo explore the theoretical justification for blinding in randomized trials and make recommendations concerning the implementation and interpretation of blinded randomized trials.Study Design and SettingA theoretical analysis was conducted of the potential for bias in randomized trials with successful blinding (ie, trials in which beliefs about allocation to treatment or control groups are independent of actual allocation). The analysis identified conditions that must be satisfied to ensure that blinding eliminates the potential for bias associated with beliefs about allocation.ResultsEven when beliefs about allocation are independent of actual allocation, they can still cause bias. The potential for bias is eliminated when the belief is uniformly one of complete ambivalence about allocation.ConclusionEven when blinding succeeds in making beliefs about allocation independent of actual allocation, beliefs about allocation may still cause bias. It is difficult to determine the extent of bias in any particular trial. Bias could be eliminated by establishing a state of complete ambivalence about the allocation of every trial participant, but universal ambivalence may be difficult to achieve and may reduce the generalizability of the trial's findings.     

Including the questionnaire with an invitation letter did not improve a telephone survey's response rate

OBJECTIVE: To determine whether including the study questionnaire with a letter of invitation improves the response rate in a telephone-based survey. STUDY DESIGN AND SETTING: This randomized controlled trial was part of a larger study to assess patient preferences for novel and controversial treatments for inflammatory bowel disease at Royal Prince Alfred Hospital, a tertiary referral teaching hospital in Sydney, Australia. RESULTS: Of 270 eligible patients, 124 (46%) were randomized to receive the questionnaire plus invitation whereas 146 (54%) were in the control group receiving a letter of invitation only. The consent rate was 26% for those receiving the questionnaire and 36% for the control group. The odds ratio for consent to participate among those sent the questionnaire to those not sent the questionnaire was 0.63 (95% CI=0.37-1.07). CONCLUSION: This study found that the advance mailing of a questionnaire to potential participants in a telephone survey reduced the likelihood of their participation.     

Three challenges described for identifying participants with missing data in trials reports,and potential solutions suggested to systematic reviewers

ObjectiveTo categorize the challenges in determining the extent of missing participant data in randomized trials and suggest potential solutions for systematic review authors.Study Design and SettingDuring the process of updating a series of Cochrane systematic reviews on the topic of anticoagulation in patients with cancer, we identified challenges and used an iterative approach to improve, and a consensus process to agree on the challenges identified, and to suggest potential ways of dealing with them. The five systematic reviews included 58 trials and 75 meta-analyses for patient-important dichotomous outcomes with 27,037 randomized participants.ResultsWe identified three categories of challenges: (1) Although systematic reviewers require information about missing data to be reported by outcome, trialists typically report the information by participant; (2) It is not always clear whether the trialists followed up participants in certain categories (e.g., noncompliers), that is, whether some categories of participants did or did not have missing data; (3) It is not always clear how the trialists dealt with missing data in their analysis (e.g., exclusion from the denominator vs. assumptions made for the numerator). We discuss potential solutions for each one of these challenges and suggest further research work.ConclusionCurrent reporting of missing data is often not explicit and transparent, and although our potential solutions to problems of suboptimal reporting may be helpful, reliable and valid characterization of the extent and nature of missing data remains elusive. Reporting of missing data in trials needs further improvement.     

抗菌药物预防胰胆管造影术后胆管炎随机对照试验的荟萃分析

目的评价预防性应用抗菌药物能否降低内镜逆行胰胆管造影(ERCP)术后胆管炎的发生率。方法检索MEDLINE、EMBASE.com、Cochrane Controlled Trial Register、中国生物医学文献数据库,收集抗菌药物预防ERCP术后胆管炎的临床随机对照研究,筛选、评价文献并提取数据进行荟萃(meta)分析。结果共纳入9篇文献,荟萃分析结果显示,抗菌药物预防并不能降低ERCP术后胆管炎的发生率(RR=0.681,95%CI0.407~1.139,P>0.05),敏感性分析结果与荟萃分析结果一致,偏倚分析提示无显著发表偏倚存在,故上述结果具有一定的可信度。结论ERCP术前不推荐常规进行抗菌药物预防。     

Reviews assessing the quality or the reporting of randomized controlled trials are increasing over time but raised questions about how quality is assessed

Objective

Many reviews specifically aimed to assess the quality of randomized controlled trials (RCTs). We evaluated the quality of reporting in such reviews.

Study Design and Setting

PubMed and the Cochrane library were searched for all reviews assessing the quality of RCTs between 1987 and 2007, and experts in the field were also contacted.

Results

We found 177 reviews published from 1987 to 2007, 58% of which were published after 2002. Of these, 131 (74%) focused on the quality of RCTs, 44 (25%) on quality of reporting, and 2 (1%) assessed both. The search strategy was well reported (92%). The criteria for assessment were reported in 97% of the reviews but were defined in only 38%. Seventy-four different items and 26 different scales were identified. Allocation sequence generation and concealment were reported in 41% and 40%, respectively, but their adequacy was assessed in 20% and 29%, respectively; scales were used in 40% and Consolidated Standards of Reporting Trials (CONSORT) checklist in 12%.

Conclusion

The number of methodological reviews has dramatically increased in recent years. Despite an improved reporting of the methodology, how quality is assessed still raises important issues. Heterogeneity of criteria used and lack of definition may limit the relevance of these reviews.     

The risk of unblinding was infrequently and incompletely reported in 300 randomized clinical trial publications

ObjectivesTo assess the proportion of clinical trials explicitly reporting the risk of unblinding, to evaluate the completeness of reporting on unblinding risk, and to describe the reported procedures involved in assessing unblinding.Study Design and SettingWe sampled at random 300 blinded randomized clinical trials indexed in PubMed in 2010. Two authors read the trial publications and extracted data independently.ResultsTwenty-four trial publications, or 8% (95% confidence interval [CI], 5, 12%), explicitly reported the risk of unblinding, of which 16 publications, or 5% (95% CI, 3, 8%), reported compromised blinding; and 8 publications, or 3% (95% CI, 1, 5%), intact blinding. The reporting on risk of unblinding in the 24 trial publications was generally incomplete. The median proportion of assessments per trial affected by unblinding was 3% (range 1–30%). The most common mechanism for unblinding was perceptible physical properties of the treatments, for example, a difference in the taste and odor of a typhoid vaccine compared with its placebo.ConclusionPublished articles on randomized clinical trials infrequently reported risk of unblinding. This may reflect a tendency for avoiding reporting actual or suspected unblinding or a genuine low risk of unblinding.     

Calcium Supplements and Risk of Cardiovascular Disease: A Meta-Analysis of Clinical Trials

Background: Recent systematic reviews and meta-analyses of randomized, double-blind, placebo-controlled trials (double-blind, placebo-controlled RCTs) have reported controversial findings regarding the associations between calcium supplements on the risk of cardiovascular disease (CVD). This meta-analysis aimed to investigate the association between them. Methods: We searched PubMed, EMBASE, the Cochrane Library, and the bibliographies of relevant articles for double-blind, placebo-controlled RCTs in November, 2020. Relative risks (RRs) with 95% confidence intervals (CIs) for the risk of cardiovascular disease were calculated using a random effects model. The main outcomes were CVD, coronary heart disease (CHD), and cerebrovascular disease. Results: A total of 13 double-blind, placebo-controlled RCTs (n = 28,935 participants in an intervention group and 14,243 in a control group)) were included in the final analysis. Calcium supplements significantly increased the risk of CVD (RR 1.15, 95% CI 1.06–1.25], I2 = 0.0%, n = 14) and CHD (RR 1.16, 95% CI 1.05–1.28], I2 = 0.0%, n = 9) in double-blind, placebo-controlled RCTs, specifically in healthy postmenopausal women. In the subgroup meta-analysis, dietary calcium intake of 700–1000 mg per day or supplementary calcium intake of 1000 mg per day significantly increased the risk of CVD and CHD. Conclusions: The current meta-analysis found that calcium supplements increased a risk of CVD by about 15% in healthy postmenopausal women.     

Comparison of balanced and random allocation in clinical trials: A simulation study

Background: Before analysing the results of a randomised controlled clinical trial in which 200 children were balanced over five prognostic factors, we wanted to know the efficiency of balanced allocation compared to simple randomisation as well as the efficiency of adjusted as compared to unadjusted statistical analysis in small and large sample sizes. Methods: A simulation study with 1000 replications of each assignment was performed for both relatively large trials (n = 100) and for small trials (n = 20). Four options for the design and analysis were studied: (1) simple randomisation with simple univariate analysis, (2) simple randomisation with multivariate modelling, (3) balanced allocation with simple univariate analysis and (4) balanced allocation with multivariate modelling. In addition, we also considered the effect of an unmeasured covariable, which was either uncorrelated or correlated with another covariate. Results/conclusion: The simulations show that a combination of balanced allocation and multivariate analysis as compared to simple randomisation and multivariate analysis leads to more valid and precise treatment effects as well as to smaller confidence intervals, especially in small trials (n = 20). Multivariate analysis with all known prognostic factors produces on average smaller Type I errors and Type II errors in balanced allocation compared to simple randomisation. If an unmeasured covariate is strongly correlated with another covariate the treatment effect is estimated more precisely as compared to an unmeasured covariate that is not correlate or less strongly correlated.     

Case reports and case series from Lancet had significant impact on medical literature

BACKGROUND AND OBJECTIVES: Case reports and case series are often the first evidence of innovative treatment, but clinical trials need to follow to substantiate this evidence. The objective of this article was to evaluate case reports or case series describing innovative treatment concerning their impact. METHODS: Case reports and case series (n < or = 10) from a high-impact journal, The Lancet, published from 1 January 1996 to 30 June 1997, were evaluated according to predefined criteria. To assess publication impact, Pubmed, Science Citation Index, the Register of Current Controlled Clinical Trials, and the Cochrance Controlled Clinical Trials Register were searched. RESULTS: Sixty-four case reports and 39 case series were identified. They were cited in average 17 times (median 6,5; range 0-336). Twenty-Four follow-up trials were identified, nine in the register of current controlled clinical trials. CONCLUSION: Case reports and case series can be well received, and have significant influence on subsequent literature and possibly on clinical practice. Many were followed by clinical trials. Often, though, they report rare conditions for which trials may not be feasible, and more or less explicitly transfer established treatment into other conditions. Overall, there is a strong publication bias favoring positive results, and opportunity should be created for publication of follow-up reports.     

临床营养研究中随机对照研究质量评价

目的评价两种主要临床营养期刊中随机对照试验（RCT）的质量。方法查阅2000～2008年《中国临床营养杂志》和《肠外与肠内营养》发表的RCT研究，按Cochrane协作网标准评价，并进行Jadad评分。结果两种期刊共发表238篇RCT研究，Jadad评分为（1．65±0．82）分。高质量RCT仅28篇（11．76％），评分为满分5分的仅5篇（2．10％）。随机分组的方法、组间可比性、纳入排除标准、盲法、撤除和退出的数量和理由、样本含量等方面存在各种问题。结论国内临床营养领域RCT研究的设计和质量控制还存在不足或欠缺，水平尚待提高。     

Label‐invariant models for the analysis of meta‐epidemiological data

Rich meta‐epidemiological data sets have been collected to explore associations between intervention effect estimates and study‐level characteristics. Welton et al proposed models for the analysis of meta‐epidemiological data, but these models are restrictive because they force heterogeneity among studies with a particular characteristic to be at least as large as that among studies without the characteristic. In this paper we present alternative models that are invariant to the labels defining the 2 categories of studies. To exemplify the methods, we use a collection of meta‐analyses in which the Cochrane Risk of Bias tool has been implemented. We first investigate the influence of small trial sample sizes (less than 100 participants), before investigating the influence of multiple methodological flaws (inadequate or unclear sequence generation, allocation concealment, and blinding). We fit both the Welton et al model and our proposed label‐invariant model and compare the results. Estimates of mean bias associated with the trial characteristics and of between‐trial variances are not very sensitive to the choice of model. Results from fitting a univariable model show that heterogeneity variance is, on average, 88% greater among trials with less than 100 participants. On the basis of a multivariable model, heterogeneity variance is, on average, 25% greater among trials with inadequate/unclear sequence generation, 51% greater among trials with inadequate/unclear blinding, and 23% lower among trials with inadequate/unclear allocation concealment, although the 95% intervals for these ratios are very wide. Our proposed label‐invariant models for meta‐epidemiological data analysis facilitate investigations of between‐study heterogeneity attributable to certain study characteristics.     

A systematic review of multivitamin and multimineral supplementation for infection

BACKGROUND: Infections are major causes of morbidity and mortality worldwide. Micronutrients have important functions in the body's immune system. This systematic review examined the evidence from randomized controlled trials (RCTs) on whether multivitamin and multimineral supplementation is effective in reducing infection. METHODS: Electronic databases searched: Cochrane Controlled Trials Register, EMBASE, MEDLINE, BIOSIS, CAB abstracts. Hand searching of nutrition journals and reference lists was carried out. RCTs and quasi-randomized trials of supplementation of adults with at least two vitamins or minerals or a combination were selected. Study results were combined in meta-analysis plots where appropriate. RESULTS: Twenty studies were included in the review. Small numbers were available for each meta-analysis. Results are presented here without the Chandra group studies. No significant difference was found in the number of episodes of infection in older people (>or = 65 years) between those supplemented and those not supplemented; (WMD) 0.06 [95% confidence interval (CI) -0.04, 0.16], P = 0.25. In other adults groups, there were significantly less episodes of infection in those supplemented; (WMD) -1.20 (95% CI -2.08, -0.32), P = 0.008. There was no significant difference between those older people supplemented and those not supplemented in the number with at least one infection; relative risk (RR) 0.98 (95% CI 0.86, 1.11), P = 0.77. Similarly, there was no significant difference in the numbers in other adult groups who had at least one episode of infection between those supplemented and those taking placebo; (RR) 0.81 (95% CI 0.65, 1.00), P = 0.06. Subgroup analyses suggested that supplemented people aged 65 years or over may benefit more if they are undernourished and supplemented for over 6 months, WMD -0.67 infections (95% CI -1.24, -0.10), P = 0.02. CONCLUSION: Further large trials are needed, particularly in undernourished older people. Trials of supplementation periods of over 6 months are recommended.     

Effect of Vitamin D Supplementation in Early Life on Children’s Growth and Body Composition: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

Background: Vitamin D deficiency during pregnancy or infancy is associated with adverse growth in children. No systematic review has been conducted to summarize available evidence on the effect of vitamin D supplementation in pregnancy and infancy on growth and body composition in children. Objective: We aim to summarize the available evidence on the effect of vitamin D supplementation in pregnancy and infancy on child growth and body composition. Method: A systematic review and meta-analysis were performed on the effects of vitamin D supplementation during early life on children’s growth and body composition (bone, lean and fat). A literature search of randomized controlled trials (RCTs) was conducted to identify relevant studies on the effects of vitamin D supplementation during pregnancy and infancy on children’s body composition (bone, lean and fat) in PubMed, EMBASE and Cochrane Library from inception to 31 December 2020. A Cochrane Risk Assessment Tool was used for quality assessment. The comparison was vitamin D supplementation vs. placebo or standard care. Random-effects and fixed-effect meta-analyses were conducted. The effects are presented as mean differences (MDs) or risk ratios (RRs) with 95% confidence intervals (CIs). Results: A total of 3960 participants from eleven randomized controlled trials were eligible for inclusion. Vitamin D supplementation during pregnancy was associated with higher triceps skinfold thickness (mm) (MD 0.33, 95% CI, 0.12, 0.54; I² = 34%) in neonates. Vitamin D supplementation during pregnancy or infancy was associated with significantly increased length for age z-score in infants at 1 year of age (MD 0.29, 95% CI, 0.03, 0.54; I² = 0%), and was associated with lower body mass index (BMI) (kg/m²) (MD −0.19, 95% CI −0.34, −0.04; I² = 0%) and body mass index z-score (BMIZ) (MD −0.12, 95% CI −0.21, −0.04; I² = 0%) in offspring at 3–6 years of age. Vitamin D supplementation during early life was not observed to be associated with children’s bone, lean or fat mass. Conclusion: Vitamin D supplementation during pregnancy or infancy may be associated with reduced adiposity in childhood. Further large clinical trials of the effects of vitamin D supplementation on childhood body composition are warranted.