Fool's gold? Why blinded trials are not always best

Democratising the design and delivery of large-scale randomised, controlled clinical trials in primary care: A personal view

BACKGROUND

Rapid identification of effective treatments for use in the community during a pandemic is vital for the well-being of individuals and the sustainability of healthcare systems and society. Furthermore, identifying treatments that do not work reduces research wastage, spares people unnecessary side effects, rationalises the cost of purchasing and stockpiling medication, and reduces inappropriate medication use. Nevertheless, only a small minority of therapeutic trials for SARS-CoV-2 infections have been in primary care: most opened too late, struggled to recruit, and few produced actionable results. Participation in research is often limited by where one lives or receives health care, and trial participants may not represent those for whom the treatments are intended.

INNOVATIVE TRIALS

The ALIC4E, PRINCIPLE and the ongoing PANORAMIC trial have randomised over 40,500 people with COVID-19. This personal view describes how these trials have innovated in: trial design (by using novel adaptive platform designs); trial delivery (by complementing traditional site-based recruitment ('the patient comes to the research') with mechanisms to enable sick, infectious people to participate without having to leave home ('taking research to the people'), and by addressing the 'inverse research participation law,' which highlights disproportionate barriers faced by those who have the most to contribute, and benefit from, research, and; in transforming the evidence base by evaluating nine medicines to support guidelines and care decisions world-wide for COVID-19 and contribute to antimicrobial stewardship.

CONCLUSION

The PRINCIPLE and PANORAMIC trials represent models of innovation and inclusivity, and exemplify the potential of primary care to lead the way in addressing pressing global health challenges.

The relationship between blinding integrity and medication efficacy in randomised-controlled trials in patients with anxiety disorders: A systematic review and meta-analysis

BACKGROUND

Blinding is thought to minimise expectancy effects and biases in double-blind randomised-controlled trials (RCTs). However, whether blinding integrity should be assessed and reported remains debated. Furthermore, it is unknown whether blinding failure influences the outcome of RCTs in anxiety disorders. We carried out a systematic review to understand whether blinding integrity is assessed and reported in anxiolytic RCTs. A secondary aim was to explore whether blinding integrity is associated with treatment efficacy.

METHOD

Our protocol was pre-registered (PROSPERO CRD42022328750). We searched electronic databases for placebo-controlled, randomised trials of medication in adults with generalised and social anxiety disorders, and in panic disorder, from 1980. We extracted data regarding blinding integrity and treatment efficacy. Risk of bias was assessed with the Cochrane risk of bias tool. Where possible, we subsequently calculated Bang's Blinding Index, and assessed the association between blinding integrity and treatment effect size.

RESULTS

Of the 247 RCTs that met inclusion criteria, we were able to obtain assessments of blinding integrity from nine (3.64%). Overall, blinding failed in five of these trials (55.56%), but blinding was intact in 80% of placebo arms. We found a significant association between reduced blinding integrity among assessors and increased treatment effect size (betas < -1.30, p's < 0.001), but this analysis involved only four studies of which two were outlying studies. In patients, we saw a non-significant trend where reduced blinding integrity in the placebo groups was associated with increased treatment efficacy, which was not present in active medication arms. [Correction added on 19 August 2024, after first online publication: Results of the RCTs and its assessment of blinding integrity have been updated.] CONCLUSION: Consistent with work in other psychiatric disorders, blinding integrity is rarely reported in anxiolytic RCTs. Where it is reported, blinding appears to often fail. We found signals that suggest unblinding of clinician assessors (driven by two studies with complete unblinding), and of patients in placebo arms, might be associated with larger treatment effect sizes. We recommend that data regarding blinding integrity, along with the reasons patients and assessors offer for their beliefs regarding group allocation, are systematically collected in RCTs of anxiolytic treatment.

Favipiravir for COVID-19 in adults in the community in PRINCIPLE, an open-label, randomised, controlled, adaptive platform trial of short- and longer-term outcomes

BACKGROUND

Evidence for the effect of favipiravir treatment of acute COVID-19 on recovery, hospital admissions and longer-term outcomes in community settings is limited.

METHODS

In this multicentre. open-label, multi-arm, adaptive platform randomised controlled trial participants aged ≥18 years in the community with a positive test for SARS-CoV-2 and symptoms lasting ≤14 days were randomised to: usual care; usual care plus favipiravir tablets (loading dose of 3600 mg in divided doses on day one, then 800 mg twice a day for four days); or, usual care plus other interventions. Co-primary endpoints were time to first self-reported recovery and hospitalisation/death related to COVID-19, within 28 days, analysed using Bayesian models. Recovery at six months was the primary longer-term outcome.

TRIAL REGISTRATION

ISRCTN86534580.

FINDINGS

The primary analysis model included 8811 SARS-CoV-2 positive mostly COVID vaccinated participants, randomised to favipiravir (n = 1829), usual care (n = 3256), and other treatments (n = 3726). Time to self-reported recovery was shorter in the favipiravir group than usual care (estimated hazard ratio 1·23 [95% credible interval 1·14 to 1·33]), a reduction of 2·98 days [1·99 to 3·94] from 16 days in median time to self-reported recovery for favipiravir versus usual care alone. COVID-19 related hospitalisations/deaths were similar (estimated odds ratio 0·99 [0·61 to 1·61]; estimated difference 0% [-0·9% to 0·6%]). 14 serious adverse events occurred in the favipiravir group and 4 in usual care. By six months, the proportion feeling fully recovered was 74·9% for favipiravir versus 71·3% for usual care (RR = 1·05, [1·02 to 1·08]).

INTERPRETATION

In this open-label trial in a largely vaccinated population with COVID-19 in the community, favipiravir did not reduce hospital admissions, but shortened time to recovery and had a marginal positive impact on long term outcomes.

Ivermectin for COVID-19 in adults in the community (PRINCIPLE): An open, randomised, controlled, adaptive platform trial of short- and longer-term outcomes

BACKGROUND

The evidence for whether ivermectin impacts recovery, hospital admissions, and longer-term outcomes in COVID-19 is contested. The WHO recommends its use only in the context of clinical trials.

METHODS

In this multicentre, open-label, multi-arm, adaptive platform randomised controlled trial, we included participants aged ≥18 years in the community, with a positive SARS-CoV-2 test, and symptoms lasting ≤14 days. Participants were randomised to usual care, usual care plus ivermectin tablets (target 300-400 μg/kg per dose, once daily for 3 days), or usual care plus other interventions. Co-primary endpoints were time to first self-reported recovery, and COVID-19 related hospitalisation/death within 28 days, analysed using Bayesian models. Recovery at 6 months was the primary, longer term outcome.

TRIAL REGISTRATION

ISRCTN86534580.

FINDINGS

The primary analysis included 8811 SARS-CoV-2 positive participants (median symptom duration 5 days), randomised to ivermectin (n = 2157), usual care (n = 3256), and other treatments (n = 3398) from June 23, 2021 to July 1, 2022. Time to self-reported recovery was shorter in the ivermectin group compared with usual care (hazard ratio 1·15 [95% Bayesian credible interval, 1·07 to 1·23], median decrease 2.06 days [1·00 to 3·06]), probability of meaningful effect (pre-specified hazard ratio ≥1.2) 0·192). COVID-19-related hospitalisations/deaths (odds ratio 1·02 [0·63 to 1·62]; estimated percentage difference 0% [-1% to 0·6%]), serious adverse events (three and five respectively), and the proportion feeling fully recovered were similar in both groups at 6 months (74·3% and 71·2% respectively (RR = 1·05, [1·02 to 1·08]) and also at 3 and 12 months.

INTERPRETATION

Ivermectin for COVID-19 is unlikely to provide clinically meaningful improvement in recovery, hospital admissions, or longer-term outcomes. Further trials of ivermectin for SARS-Cov-2 infection in vaccinated community populations appear unwarranted.

FUNDING

UKRI/National Institute of Health Research (MC_PC_19079).

Placebo analgesia in physical and psychological interventions: Systematic review and meta-analysis of three-armed trials

BACKGROUND

The magnitude of placebo effects from physical and psychological 'sham' is unknown but could impact efficacy trials and treatment understanding. To quantify placebo effects, this systematic review of three-armed randomised controlled trials (RCTs) of physical and psychological interventions for pain compared outcomes in 'sham' control intervention and non-exposure arms.

METHODS

RCTs with treatment, 'sham' control intervention, and non-exposure groups were included, enrolling adults with any pain. A protocol was pre-registered (PROSPERO: CRD42023413324), and twelve databases searched from 2008 to July 2023. Trial methods and blinding were analysed descriptively and risk of bias assessed. Meta-analysis of pain measures at short-, medium- and long-term was performed with random-effects models of standardised mean differences (SMD).Studies were sub-grouped according to control intervention type.

RESULTS

Seventeen RCTs were included. The average short-term placebo effect was small (0.21 SMD, 0.1-0.33 95% CI, p = 0.0002, 1440 participants). It showed no heterogeneity (Tau2  = 0.1, I2  = 11%, p = 0.3), preventing meta-regression analyses of effect modifiers. However, sub-group analyses revealed larger placebo effects in manual control interventions compared to disabled devices and miscellaneous control interventions. Overall, placebo analgesia accounted for 39% of treatments' short-term effectiveness. No placebo effects were found at medium-term (7 RCTs, 381 participants) or long-term follow-up (3 RCTs, 173 participants).

CONCLUSIONS

The observed placebo analgesia has mechanistic and methodological implications, though its clinical importance may be limited. Control intervention design affects placebo effects, highlighting the importance of considering methodology in RCT interpretation. Review limitations include a small number of long-term studies and sample heterogeneity.

SIGNIFICANCE

This systematic review directly quantifies placebo effects from physical and psychological 'sham' control interventions and compares them to treatments' overall effectiveness. By doing so, the review enhances our understanding of placebo effects, their relative contribution in clinical trials, and their susceptibly to trial design. It poses further questions regarding the influence of blinding, participant expectations, and features of the therapeutic context. Overall, the insights provided by this review carry methodological significance and are important for the interpretation and synthesis of efficacy trials in this field.

Influence of lack of blinding on the estimation of medication-related harms: a retrospective cohort study of randomized controlled trials

BACKGROUND

Empirical evidence suggests that lack of blinding may be associated with biased estimates of treatment benefit in randomized controlled trials, but the influence on medication-related harms is not well-recognized. We aimed to investigate the association between blinding and clinical trial estimates of medication-related harms.

METHODS

We searched PubMed from January 1, 2015, till January 1, 2020, for systematic reviews with meta-analyses of medication-related harms. Eligible meta-analyses must have contained trials both with and without blinding. Potential covariates that may confound effect estimates were addressed by restricting trials within the comparison or by hierarchical analysis of harmonized groups of meta-analyses (therefore harmonizing drug type, control, dosage, and registration status) across eligible meta-analyses. The weighted hierarchical linear regression was then used to estimate the differences in harm estimates (odds ratio, OR) between trials that lacked blinding and those that were blinded. The results were reported as the ratio of OR (ROR) with its 95% confidence interval (CI).

RESULTS

We identified 629 meta-analyses of harms with 10,069 trials. We estimated a weighted average ROR of 0.68 (95% CI: 0.53 to 0.88, P < 0.01) among 82 trials in 20 meta-analyses where blinding of participants was lacking. With regard to lack of blinding of healthcare providers or outcomes assessors, the RORs were 0.68 (95% CI: 0.53 to 0.87, P < 0.01 from 81 trials in 22 meta-analyses) and 1.00 (95% CI: 0.94 to 1.07, P = 0.94 from 858 trials among 155 meta-analyses) respectively. Sensitivity analyses indicate that these findings are applicable to both objective and subjective outcomes.

CONCLUSIONS

Lack of blinding of participants and health care providers in randomized controlled trials may underestimate medication-related harms. Adequate blinding in randomized trials, when feasible, may help safeguard against potential bias in estimating the effects of harms.

The impact of blinding on estimated treatment effects in randomized clinical trials on acupuncture: A meta-epidemiological study

OBJECTIVE

To evaluate the sole impact of blinding patients and outcome assessors in acupuncture randomized controlled trials (RCTs) on treatment effects while considering the type of outcome measures.

METHODS

We searched databases for the meta-analyses on acupuncture with both blinded and non-blinded RCTs. Mixed-effects meta-regression models estimated the average ratio of odds ratios (ROR) and differences in standardized mean differences (dSMD) for non-blinded RCTs versus blinded mixed-effects meta-regression model.

RESULTS

The study included 96 meta-analyses (1012 trials). The average ROR for lack of patient blinding was 1.08 (95% confidence intervals 0.79-1.49) in 18 meta-analyses with binary patient-reported outcomes. The average ROR for lack of outcome assessor blinding was 0.98 (0.77-1.24) in 43 meta-analyses with binary subjective outcomes. The average dSMD was -0.38 (-0.96 to 0.20) in 10 meta-analyses with continuous patient-reported outcomes. The average dSMD was -0.13 (-0.45 to 0.18) in 25 meta-analyses with continuous subjective outcomes. The results of the subgroup analysis were consistent with the primary analysis findings.

CONCLUSIONS

Blinding of participants and outcome assessors does not significantly influence acupuncture treatment efficacy. It underscores the practical difficulties of blinding in acupuncture RCTs and the necessity to distinguish between trials with and without successful blinding to understand treatment expectations' effects. Enhancing blinding procedures' quality and assessment in future research is crucial for improving RCTs' internal validity and reliability.

Platform adaptive trial of novel antivirals for early treatment of COVID-19 In the community (PANORAMIC): protocol for a randomised, controlled, open-label, adaptive platform trial of community novel antiviral treatment of COVID-19 in people at increased risk of more severe disease

INTRODUCTION

There is an urgent need to determine the safety, effectiveness and cost-effectiveness of novel antiviral treatments for COVID-19 in vaccinated patients in the community at increased risk of morbidity and mortality from COVID-19.

METHODS AND ANALYSIS

PANORAMIC is a UK-wide, open-label, prospective, adaptive, multiarm platform, randomised clinical trial that evaluates antiviral treatments for COVID-19 in the community. A master protocol governs the addition of new antiviral treatments as they become available, and the introduction and cessation of existing interventions via interim analyses. The first two interventions to be evaluated are molnupiravir (Lagevrio) and nirmatrelvir/ritonavir (Paxlovid).

ELIGIBILITY CRITERIA

community-dwelling within 5 days of onset of symptomatic COVID-19 (confirmed by PCR or lateral flow test), and either (1) aged 50 years and over, or (2) aged 18-49 years with qualifying comorbidities. Registration occurs via the trial website and by telephone. Recruitment occurs remotely through the central trial team, or in person through clinical sites. Participants are randomised to receive either usual care or a trial drug plus usual care. Outcomes are collected via a participant-completed daily electronic symptom diary for 28 days post randomisation. Participants and/or their Trial Partner are contacted by the research team after days 7, 14 and 28 if the diary is not completed, or if the participant is unable to access the diary. The primary efficacy endpoint is all-cause, non-elective hospitalisation and/or death within 28 days of randomisation. Multiple prespecified interim analyses allow interventions to be stopped for futility or superiority based on prespecified decision criteria. A prospective economic evaluation is embedded within the trial.

ETHICS AND DISSEMINATION

Ethical approval granted by South Central-Berkshire REC number: 21/SC/0393; IRAS project ID: 1004274. Results will be presented to policymakers and at conferences, and published in peer-reviewed journals.

TRIAL REGISTRATION NUMBER

ISRCTN30448031; EudraCT number: 2021-005748-31.

Blinding and sham control methods in trials of physical, psychological, and self-management interventions for pain (article II): a meta-analysis relating methods to trial results

ABSTRACT

Sham interventions in randomized clinical trials (RCTs) of physical, psychological, and self-management (PPS) therapies for pain are highly variable in design and believed to contribute to poor internal validity. However, it has not been formally tested whether the extent to which sham controls resemble the treatment under investigation consistently affects trial outcomes, such as effect sizes, differential attrition, participant expectancy, and blinding effectiveness. Placebo- or sham-controlled RCTs of PPS interventions of clinical pain populations were searched in 12 databases. The similarity of control interventions to the experimental treatment was rated across 25 features. Meta-regression analyses assessed putative links between employed control interventions, observed effect sizes in pain-related outcomes, attrition, and blinding success. The sample included 198 unique control interventions, dominated by manual therapy and chronic musculoskeletal pain research. Meta-analyses indicated small-to-moderate benefits of active treatments over control interventions, across subgroups of manual therapies, exercise, and rehabilitation, and psychological intervention trials. Multiple meta-regression modelling demonstrated that similarity between sham control and tested interventions predicted variability in pain-related outcomes, attrition, and blinding effectiveness. Influential variables were differences relating to the extent of intervention exposure, participant experience, and treatment environments. The results support the supposed link between blinding methods and effect sizes, based on a large and systematically sourced overview of methods. However, challenges to effective blinding are complex and often difficult to discern from trial reports. Nonetheless, these insights have the potential to change trial design, conduct, and reporting and will inform guideline development.

Blinding and sham control methods in trials of physical, psychological, and self-management interventions for pain (article I): a systematic review and description of methods

ABSTRACT

Blinding is challenging in randomised controlled trials of physical, psychological, and self-management therapies for pain, mainly because of their complex and participatory nature. To develop standards for the design, implementation, and reporting of control interventions in efficacy and mechanistic trials, a systematic overview of currently used sham interventions and other blinding methods was required. Twelve databases were searched for placebo or sham-controlled randomised clinical trials of physical, psychological, and self-management treatments in a clinical pain population. Screening and data extraction were performed in duplicate, and trial features, description of control methods, and their similarity to the active intervention under investigation were extracted (protocol registration ID: CRD42020206590). The review included 198 unique control interventions, published between 2008 and December 2021. Most trials studied people with chronic pain, and more than half were manual therapy trials. The described control interventions ranged from clearly modelled based on the active treatment to largely dissimilar control interventions. Similarity between control and active interventions was more frequent for certain aspects (eg, duration and frequency of treatments) than others (eg, physical treatment procedures and patient sensory experiences). We also provide an overview of additional, potentially useful methods to enhance blinding, as well as the reporting of processes involved in developing control interventions. A comprehensive picture of prevalent blinding methods is provided, including a detailed assessment of the resemblance between active and control interventions. These findings can inform future developments of control interventions in efficacy and mechanistic trials and best-practice recommendations.

Evaluating the Performance and Perception of a Stoma Bag Full-Circle Filter in People with a Colostomy or an Ileostomy-Two Randomized Crossover Trials

Stoma bag filter-related issues, such as ballooning (the bag filling with gas), remain highly prevalent among users. The full-circle filter was purposely designed to reduce ballooning through the inclusion of a unique, full-circle pre-filter. Two similar randomized crossover trials were conducted to compare the performance of the full-circle filter with a dual filter in adults with a colostomy (n = 20) or an ileostomy (n = 20). The frequency of ballooning was significantly lower with the full-circle filter versus the dual filter in participants with a colostomy (p < 0.0007) and in participants with an ileostomy (p < 0.0001). No significant differences were observed in the frequency of other issues (pancaking, odor problems, and ostomy solution discretion) between the filters. On average, participants with an ileostomy wore ostomy solutions with the full-circle filter for 3.3 h longer than ostomy solutions with the dual filter (p < 0.0001); wear-time in users with a colostomy was comparable between the filters. Considering the lack of published research on stoma bag filters and the high prevalence of filter-related issues, these data provide important information for health care practitioners who support people living with a stoma.

Enhancing opportunistic recruitment and retention in primary care trials: lessons learned from a qualitative study embedded in the Cranberry for Urinary Tract Infection (CUTI) feasibility trial

Background

Opportunistic recruitment in primary care is challenging due to the inherent unpredictability of incident conditions, and workload and time pressures. Many clinical trials do not recruit to target, leading to equivocal answers to research questions. Learning from the experiences of patients and recruiters to trials of incident conditions has the potential to improve recruitment and retention to future trials, thereby enhancing the quality and impact of research findings. The aim of this research was to learn from the trial experiences of UTI patients and recruiters to the Cranberry for UTI (CUTI) trial, to help plan an adequately powered trial of similar design.

Methods

One-to-one semi-structured interviews were embedded within the CUTI feasibility trial, an open-label, randomised feasibility trial of cranberry extract for symptoms of acute, uncomplicated Urinary Tract Infection (UTI) in primary care. Interviews were conducted with a sample of: CUTI trial participants; non-CUTI trial UTI patients; and, recruiters to the CUTI trial. Verbatim transcripts were analysed thematically.

Results

Twenty-six patients with UTI and eight recruiters (nurses and GPs) to the CUTI trial were interviewed. Three themes were developed around: reasons for participating in research; barriers to opportunistic recruitment; and, UTI patients’ experiences of trial procedures. Recruiters found that targeted electronic prompts directed at healthcare practitioners based in clinics where patients with incident conditions were likely to present (e.g. minor illness clinic) were more effective than generic prompts (e.g. desk prompts) at filtering patients from their usual clinical pathway to research clinics. Using a script to explain the delayed antibiotic trial group to patients was found to be helpful, and may have served to boost recruitment. For UTI patients, using an electronic diary to rate their symptoms was considered an acceptable medium, and often preferable to using a paper diary or mobile phone application.

Conclusions

The use of targeted prompts directed at clinicians, a script to explain trial groups that may be deemed less desirable, and an appropriate diary format for patient-reported outcomes, may help to improve trial recruitment and retention.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12875-022-01796-7.

Blinding of study statisticians in clinical trials: a qualitative study in UK clinical trials units

Background

Blinding is an established approach in clinical trials which aims to minimise the risk of performance and detection bias. There is little empirical evidence to guide UK clinical trials units (CTUs) about the practice of blinding statisticians. Guidelines recommend that statisticians remain blinded to allocation prior to the final analysis. As these guidelines are not based on empirical evidence, this study undertook a qualitative investigation relating to when and how statisticians should be blinded in clinical trials.

Methods

Data were collected through online focus groups with various stakeholders who work in the delivery and oversight of clinical trials. Recordings of the focus groups were transcribed verbatim and thematic analysis was used to analyse the transcripts.

Results

Thirty-seven participants from 19 CTUs participated in one of six focus groups. Four main themes were identified, namely statistical models of work, factors affecting the decision to blind statisticians, benefits of blinding/not blinding statisticians and practicalities. Factors influencing the decision to blind the statistician included available resources, study design and types of intervention and outcomes and analysis.

Although blinding of the statistician is perceived as a desirable mitigation against bias, there was uncertainty about the extent to which an unblinded statistician might impart bias. Instead, in most cases, the insight that the statistician offers was deemed more important to delivery of a trial than the risk of bias they may introduce if unblinded.

Blinding of statisticians was only considered achievable with the appropriate resource and staffing, which were not always available. In many cases, a standard approach to blinding was therefore considered unrealistic and impractical; hence the need for a proportionate risk assessment approach identifying possible mitigations.

Conclusions

There was wide variation in practice between UK CTUs regarding the blinding of trial statisticians. A risk assessment approach would enable CTUs to identify risks associated with unblinded statisticians conducting the final analysis and alternative mitigation strategies. The findings of this study will be used to design guidance and a tool to support this risk assessment process.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13063-022-06481-9.

Hypnotherapy for irritable bowel syndrome: patient expectations and perceptions

INTRODUCTION

Numerous studies have shown that hypnotherapy (HT) is effective in irritable bowel syndrome (IBS) using traditional symptom severity end points. However, there is now interest in capturing the patient's perception of their illness and treatment because what patients expect from their treatment may differ from that of their healthcare provider.

OBJECTIVE

To record patient perceptions and expectations of hypnotherapy as well as their symptom response.

METHODS

150 consecutive IBS patients (116 females, 34 males, aged 16-81 years) receiving hypnotherapy completed questionnaires recording IBS symptom severity, quality of life, noncolonic symptoms, anxiety and depression levels before and after treatment. Their expectations and perceptions of HT were also recorded, including a free text reflection.

RESULTS

121 patients (81%) responded to treatment consistent with our previous experience. Symptom severity scores, noncolonic symptoms, quality of life, anxiety and depression significantly all improved after HT (p < 0.001). Expectancy of an improvement with hypnotherapy was greater in those who did not respond to treatment (63%) than those who did (57%, p < 0.001). Scepticism and apprehension were common before treatment and replaced with enthusiasm afterwards. Free text responses after treatment were overwhelmingly positive. Patients also reported a variety of other benefits and even 20 of 29 symptom nonresponders (70%) still considered treatment worthwhile.

CONCLUSION

Although initially perceived negatively, hypnotherapy improved symptoms and resulted in a wide range of additional benefits. Expectation did not necessarily influence outcome. Recording IBS symptoms alone does not fully capture the patient's experience of treatment and needs to be considered in future research.

Association Between Lack of Blinding and Mortality Results in Critical Care Randomized Controlled Trials: A Meta-Epidemiological Study

OBJECTIVES

To investigate whether intervention effect estimates for mortality differ between blinded and nonblinded randomized controlled trials conducted in critical care. We used a meta-epidemiological approach, comparing effect estimates between blinded and nonblinded randomized controlled trials for the same research question.

DATA SOURCES

Systematic reviews and meta-analyses of randomized controlled trials evaluating a therapeutic intervention on mortality in critical care, published between January 2009 and March 2019 in high impact factor general medical or critical care journals and by Cochrane.

DATA EXTRACTION

For each randomized controlled trial included in eligible meta-analyses, we evaluated whether the trial was blinded (i.e., double-blinded and/or reporting adequate methods) or not (i.e., open-label, single-blinded, or unclear). We collected risk of bias evaluated by the review authors and extracted trial results.

DATA SYNTHESIS

Within each meta-analysis, we compared intervention effect estimates between blinded and nonblinded randomized controlled trials by using a ratio of odds ratio (< 1 indicates larger estimates in nonblinded than blinded randomized controlled trials). We then combined ratio of odds ratios across meta-analyses to obtain the average relative difference between nonblinded and blinded trials. Among 467 randomized controlled trials included in 36 meta-analyses, 267 (57%) were considered blinded and 200 (43%) nonblinded. Intervention effect estimates were statistically significantly larger in nonblinded than blinded trials (combined ratio of odds ratio, 0.91; 95% CI, 0.84-0.99). We found no heterogeneity across meta-analyses (p = 0.72; I2 = 0%; τ2 = 0). Sensitivity analyses adjusting the main analysis on risk of bias items yielded consistent results.

CONCLUSIONS

Intervention effect estimates of mortality were slightly larger in nonblinded than blinded randomized controlled trials conducted in critical care, but confounding cannot be excluded. Blinding of both patients and personnel is important to consider when possible in critical care trials, even when evaluating mortality.

Improving the trustworthiness of findings from nutrition evidence syntheses: assessing risk of bias and rating the certainty of evidence

Suboptimal diet is recognized as a leading modifiable risk factor for non-communicable diseases. Non-randomized studies (NRSs) with patient relevant outcomes provide many insights into diet-disease relationships. Dietary guidelines are based predominantly on findings from systematic reviews of NRSs-mostly prospective observational studies, despite that these have been repeatedly criticized for yielding potentially less trustworthy results than randomized controlled trials (RCTs). It is assumed that these are a result of bias due to prevalent-user designs, inappropriate comparators, residual confounding, and measurement error. In this article, we aim to highlight the importance of applying risk of bias (RoB) assessments in nutritional studies to improve the credibility of evidence of systematic reviews. First, we discuss the importance and challenges of dietary RCTs and NRSs, and provide reasons for potentially less trustworthy results of dietary studies. We describe currently used tools for RoB assessment (Cochrane RoB, and ROBINS-I), describe the importance of rigorous RoB assessment in dietary studies and provide examples that further the understanding of the key issues to overcome in nutrition research. We then illustrate, by comparing the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) approach with current approaches used by United States Department of Agriculture Dietary Guidelines for Americans, and the World Cancer Research Fund, how to establish trust in dietary recommendations. Our overview shows that the GRADE approach provides more transparency about the single domains for grading the certainty of the evidence and the strength of recommendations. Despite not increasing the certainty of evidence itself, we expect that the rigorous application of the Cochrane RoB and the ROBINS-I tools within systematic reviews of both RCTs and NRSs and their integration within the GRADE approach will strengthen the credibility of dietary recommendations.

Measuring the success of blinding in placebo-controlled trials: Should we be so quick to dismiss it?

'Blinding' involves concealing knowledge of which trial participants received the interventions from participants themselves and other trial personnel throughout the trial. Blinding reduces bias arising from the beliefs and expectations of these groups. It is agreed that where possible, blinding should be attempted, for example by ensuring that experimental and control treatments look the same. However, there is a debate about if we should measure whether blinding has been successful, this manuscript will discuss this controversy, including the benefits and risks of measuring blinding within the randomised controlled trial.

Blinding in Clinical Trials: Seeing the Big Picture

Blinding mitigates several sources of bias which, if left unchecked, can quantitively affect study outcomes. Blinding remains under-utilized, particularly in non-pharmaceutical clinical trials, but is often highly feasible through simple measures. Although blinding is generally viewed as an effective method by which to eliminate bias, blinding does also pose some inherent limitations, and it behooves clinicians and researchers to be aware of such caveats. This article will review general principles for blinding in clinical trials, including examples of useful blinding techniques for both pharmaceutical and non-pharmaceutical trials, while also highlighting the limitations and potential consequences of blinding. Appropriate reporting on blinding in trial protocols and manuscripts, as well as future directions for blinding research, will also be discussed.

Platform Randomised trial of INterventions against COVID-19 In older peoPLE (PRINCIPLE): protocol for a randomised, controlled, open-label, adaptive platform, trial of community treatment of COVID-19 syndromic illness in people at higher risk

INTRODUCTION

There is an urgent need to idenfy treatments for COVID-19 that reduce illness duration and hospital admission in those at higher risk of a longer illness course and complications.

METHODS AND ANALYSIS

The Platform Randomised trial of INterventions against COVID-19 In older peoPLE trial is an open-label, multiarm, prospective, adaptive platform, randomised clinical trial to evaluate potential treatments for COVID-19 in the community. A master protocol governs the addition of new interventions as they become available, as well as the inclusion and cessation of existing intervention arms via frequent interim analyses. The first three interventions are hydroxychloroquine, azithromycin and doxycycline. Eligible participants must be symptomatic in the community with possible or confirmed COVID-19 that started in the preceding 14 days and either (1) aged 65 years and over or (2) aged 50-64 years with comorbidities. Recruitment is through general practice, health service helplines, COVID-19 'hot hubs' and directly through the trial website. Participants are randomised to receive either usual care or a study drug plus usual care, and outcomes are collected via daily online symptom diary for 28 days from randomisation. The research team contacts participants and/or their study partner following days 7, 14 and 28 if the online diary is not completed. The trial has two coprimary endpoints: time to first self-report of feeling recovered from possible COVID-19 and hospital admission or death from possible COVID-19 infection, both within 28 days from randomisation. Prespecified interim analyses assess efficacy or futility of interventions and to modify randomisation probabilities that allocate more participants to interventions with better outcomes.

ETHICS AND DISSEMINATION

Ethical approval Ref: 20/SC/0158 South Central - Berkshire Research Ethics Committee; IRAS Project ID: 281958; EudraCT Number: 2020-001209-22. Results will be presented to policymakers and at conferences and published in peer-reviewed journals.

TRIAL REGISTRATION NUMBER

ISRCTN86534580.

Effect of resistance training with blood flow restriction on muscle damage markers in adults: A systematic review

Background

The purpose of this review was to systematically analyze the evidence regarding the occurrence of muscle damage (changes in muscle damage markers) after resistance training with blood flow restriction sessions.

Materials and methods

This systematic review was conducted in accordance with the PRISMA recommendations. Two researchers independently and blindly searched the following electronic databases: PubMed, Scopus, Web of Science, CINAHL, LILACS and SPORTdicus. Randomized and non-randomized clinical trials which analyzed the effect of resistance training with blood flow restriction on muscle damage markers in humans were included. The risk of bias assessment was performed by two blinded and independent researchers using the RoB2 tool.

Results

A total of 21 studies involving 352 healthy participants (men, n = 301; women, n = 51) were eligible for this review. The samples in 66.6% of the studies (n = 14) were composed of untrained individuals. All included studies analyzed muscle damage using indirect markers. Most studies had more than one muscle damage marker and Delayed Onset Muscle Soreness was the measure most frequently used. The results for the occurrence of significant changes in muscle damage markers after low-load resistance training with blood flow restriction sessions were contrasting, and the use of a pre-defined repetition scheme versus muscle failure seems to be the determining point for this divergence, mainly in untrained individuals.

Conclusions

In summary, the use of sets until failure is seen to be determinant for the occurrence of significant changes in muscle damage markers after low-load resistance training with blood flow restriction sessions, especially in individuals not used to resistance exercise.

Trial registration

Register number: PROSPERO number: CRD42020177119.

Oseltamivir for coronavirus illness: post-hoc exploratory analysis of an open-label, pragmatic, randomised controlled trial in European primary care from 2016 to 2018

BACKGROUND

Patients infected with the novel coronavirus (SARS-CoV-2) are being treated empirically with oseltamivir, but there is little evidence from randomised controlled trials to support the treatment of coronavirus infections with oseltamivir.

AIM

To determine whether adding oseltamivir to usual care reduces time to recovery in symptomatic patients who have tested positive for coronavirus (not including SARS-CoV-2).

DESIGN AND SETTING

Exploratory analysis of data from an open-label, pragmatic, randomised controlled trial during three influenza seasons, from 2016 to 2018, in primary care research networks, in 15 European countries.

METHOD

Patients aged ≥1 year presenting to primary care with influenza-like illness (ILI), and who tested positive for coronavirus (not including SARS-CoV-2), were randomised to usual care or usual care plus oseltamivir. The primary outcome was time to recovery defined as a return to usual activities, with minor or absent fever, headache, and muscle ache.

RESULTS

Coronaviruses (CoV-229E, CoV-OC43, CoV-KU1 and CoV-NL63) were identified in 308 (9%) out of 3266 randomised participants in the trial; 153 of these were allocated to usual care and 155 to usual care plus oseltamivir; the primary outcome was ascertained in 136 and 147 participants, respectively. The median time to recovery was shorter in patients randomised to oseltamivir: 4 days (interquartile range [IQR] 3-6) versus 5 days (IQR 3-8; hazard ratio 1.31; 95% confidence interval = 1.03 to 1.66; P = 0.026).

CONCLUSION

Primary care patients with ILI testing positive for coronavirus (not including SARS-CoV-2) recovered sooner when oseltamivir was added to usual care compared with usual care alone. This may be of relevance to the primary care management of COVID-19.

The Trials and Tribulations of Selecting Comparison Groups in Randomized Trials of Nonpharmacological Complementary and Integrative Health Interventions

Editor's Note: For over two decades, JACM Editorial Board member Karen Sherman, PhD has been among the most respected clinical trialists in complementary and integrative health research. The epidemiologist and Senior Researcher at Kaiser Permanente Washington Health Research Institute has focused on pain conditions and has led or been part of teams exploring the roles of such therapies as yoga, acupuncture, mind-body and manual therapies. In this Invited Commentary, Sherman shares wisdom gleaned from the process: trial designs, principles for selecting controls, benefits and liabilities of placebo and sham controls, attention controls, usual care controls, and more. She also discusses the effects of comparison groups on sample sizes, comparison groups for mechanistic studies, and other comparison groups' considerations. This commentary should prove a useful primer wherever research methods in complementary and integrative health are taught. We are pleased to offer it here through JACM. -John Weeks, Editor-in-Chief, JACM (johnweeks-integrator.com).