Characteristics, consent patterns, and challenges of randomized trials using the Trials within Cohorts (TwiCs) design - A scoping review.

OBJECTIVES: Trials within Cohorts (TwiCs) is a pragmatic design approach that may overcome frequent challenges of traditional randomized trials such as slow recruitment, burdensome consent procedures, or limited external validity. This scoping review aims to identify all randomized controlled trials using the TwiCs design and to summarize their design characteristics, ways to obtain informed consent, output, reported challenges and mitigation strategies. STUDY DESIGN AND SETTING: Systematic search of Medline, Embase, Cochrane, trial registries and citation tracking up to December 2022. TwiCs were defined as randomized trials embedded in a cohort with postrandomization consent for the intervention group and no specific postrandomization consent for the usual care control group. Information from identified TwiCs was extracted in duplicate from protocols, publications, and registry entries. We analyzed the information descriptively and qualitatively to highlight methodological challenges and solutions related to nonuptake of interventions and informed consent procedure. RESULTS: We identified a total of 46 TwiCs conducted between 2005 and 2022 in 14 different countries by a handful of research groups. The most common medical fields were oncology (11/46; 24%), infectious diseases (8/46; 17%), and mental health (7/46; 15%). A typical TwiCs was investigator-initiated (46/46; 100%), publicly funded (36/46; 78%), and recruited outpatients (27/46; 59%). Excluding eight pilot trials, only 16/38 (42%) TwiCs adjusted their calculated sample size for nonuptake of the intervention, anticipating a median nonuptake of 25% (interquartile range 10%-32%) in the experimental arm. Seventeen TwiCs (45%) planned analyses to adjust effect estimates for nonuptake. Regarding informed consent, we observed three patterns: 1) three separate consents for cohort participation, randomization, and intervention (17/46; 37%); 2) combined consent for cohort participation and randomization and a separate intervention consent (10/46; 22%); and 3) consent only for cohort participation and intervention (randomization consent not mentioned; 19/46; 41%). CONCLUSION: Existing TwiCs are globally scattered across a few research groups covering a wide range of medical fields and interventions. Despite the potential advantages, the number of TwiCs remains small. The variability in consent procedures and the possibility of substantial nonuptake of the intervention warrants further research to guide the planning, implementation, and analysis of TwiCs.

Characteristics, Progression, and Output of Randomized Platform Trials: A Systematic Review.

Importance: Platform trials have become increasingly common, and evidence is needed to determine how this trial design is actually applied in current research practice. Objective: To determine the characteristics, progression, and output of randomized platform trials. Evidence Review: In this systematic review of randomized platform trials, Medline, Embase, Scopus, trial registries, gray literature, and preprint servers were searched, and citation tracking was performed in July 2022. Investigators were contacted in February 2023 to confirm data accuracy and to provide updated information on the status of platform trial arms. Randomized platform trials were eligible if they explicitly planned to add or drop arms. Data were extracted in duplicate from protocols, publications, websites, and registry entries. For each platform trial, design features such as the use of a common control arm, use of nonconcurrent control data, statistical framework, adjustment for multiplicity, and use of additional adaptive design features were collected. Progression and output of each platform trial were determined by the recruitment status of individual arms, the number of arms added or dropped, and the availability of results for each intervention arm. Findings: The search identified 127 randomized platform trials with a total of 823 arms; most trials were conducted in the field of oncology (57 [44.9%]) and COVID-19 (45 [35.4%]). After a more than twofold increase in the initiation of new platform trials at the beginning of the COVID-19 pandemic, the number of platform trials has since declined. Platform trial features were often not reported (not reported: nonconcurrent control, 61 of 127 [48.0%]; multiplicity adjustment for arms, 98 of 127 [77.2%]; statistical framework, 37 of 127 [29.1%]). Adaptive design features were only used by half the studies (63 of 127 [49.6%]). Results were available for 65.2% of closed arms (230 of 353). Premature closure of platform trial arms due to recruitment problems was infrequent (5 of 353 [1.4%]). Conclusions and Relevance: This systematic review found that platform trials were initiated most frequently during the COVID-19 pandemic and declined thereafter. The reporting of platform features and the availability of results were insufficient. Premature arm closure for poor recruitment was rare.

Minimal important difference estimates for patient-reported outcomes: A systematic survey.

OBJECTIVES: The objective of the study was to develop an inventory summarizing all anchor-based minimal important difference (MID) estimates for patient-reported outcome measures (PROMs) available in the medical literature. STUDY DESIGN AND SETTING: We searched MEDLINE, EMBASE, CINAHL, PsycINFO, and the Patient-Reported Outcome and Quality of Life Instruments Database internal library (January 1989-October 2018). We included primary studies empirically calculating an anchor-based MID estimate for any PROM in adults and adolescents. Pairs of reviewers independently screened and selected studies, extracted data, and evaluated the credibility of the MIDs. RESULTS: We identified 585 eligible studies, the majority conducted in Europe (n = 211) and North America (n = 179), reporting 5,324 MID estimates for 526 distinct PROMs. Investigators conducted their studies in the context of patients receiving surgical (n = 105, 18%), pharmacological (n = 85, 15%), rehabilitation (n = 65, 11%), or a combination of interventions (n = 194, 33%). Of all MID estimates, 59% (n = 3,131) used a global rating of change anchor. Major credibility limitations included weak correlation (n = 1,246, 23%) or no information regarding the correlation (n = 3,498, 66%) between the PROM and anchor and imprecision in the MID estimate (n = 2,513, 47%). CONCLUSION: A large number of MIDs for assisting in the interpretation of PROMs exist. The MID inventory will facilitate the use of MID estimates to inform the interpretation of the magnitude of treatment effects in clinical research and guideline development.

Characteristics and interpretation of subgroup analyses based on tumour characteristics in randomised trials testing target-specific anticancer drugs: design of a systematic survey.

BACKGROUND: Target-specific anticancer drugs are under rapid development. Little is known, however, about the risk of administering target-specific drugs to patients who have tumours with molecular alterations or other characteristics that can make the drug ineffective or even harmful. An increasing number of randomised clinical trials (RCTs) investigating target-specific anticancer drugs include subgroup analyses based on tumour characteristics. Such subgroup analyses have the potential to be more credible and influential than subgroup analyses based on traditional factors such as sex or tumour stage. In addition, they may more frequently lead to qualitative subgroup effects, that is, show benefit in one but harm in another subgroup of patients (eg, if the tumour characteristic makes the drug ineffective or even enhance tumour growth). If so, subgroup analyses based on tumour characteristics would be highly relevant for patient safety. The aim of this study is to systematically assess the frequency and characteristics of subgroup analyses based on tumour characteristics, the frequency of qualitative subgroup effects, their credibility, and the interpretations that investigators and guidelines developers report. METHODS AND ANALYSIS: We will perform a systematic survey of 433 RCTs testing the effect of target-specific anticancer drugs. Teams of methodologically trained investigators and oncologists will identify eligible studies, extract relevant data and assess the credibility of putative subgroup effects using a recently developed formal instrument. We will systematically assess how trial investigators interpret apparent subgroup effects based on tumour characteristics and the extent to which they influence subsequent practice guidelines. Our results will provide empirical data characterising an increasingly used type of subgroup analysis in cancer trials and its potential impact on precision medicine to predict benefit or harm. ETHICS AND DISSEMINATION: Formal ethical approval is not required for this study. We will disseminate the findings in a peer-reviewed and open-access journal publication.

Rituximab in primary central nervous system lymphoma-A systematic review and meta-analysis.

The CD-20 antibody rituximab is a standard component of treatment of non-Hodgkin B-cell lymphomas, including diffuse large B-cell lymphoma (DLBCL). Primary DLBCL of the central nervous system, also called primary central nervous system lymphoma (PCNSL), is a DLBCL confined to the central nervous system. There has been debate whether intravenous rituximab accumulates sufficiently in the central nervous system to exert an effect. In this systematic review, we assess the benefits and harms of rituximab in the treatment of immunocompetent patients with PCNSL. By searching MEDLINE, CENTRAL, and ClincialTrials.gov up to March 2019, we identified randomized controlled trials (RCTs) investigating the effect of rituximab in patients with PCNSL. We extracted study characteristics and results, assessed risk of bias, performed trial-level random-effects meta-analyses, and graded the certainty of evidence. The protocol was registered with PROSPERO (CRD42019121965). Main outcomes were overall survival (time to death), progression-free survival (time to progression or death), quality of life, grades 3 and 4 toxicity, and treatment-related mortality. We included two RCTs with a total of 343 participants. Overall survival was not statistically significantly improved (HR 0.76; 95% CI, 0.52-1.12; low certainty), with 187 fewer to 39 more deaths after 2 years in 1000 treated patients. Low certainty of evidence indicated that rituximab improved progression-free survival (HR 0.65; 95% CI, 0.45-0.95), which translated into 137 fewer progressions or deaths after 2 years in 1000 treated patients (231 to 18 fewer). None of the RCTs provided data on quality of life. We found no evidence that rituximab increased grades 3 and 4 toxicity or treatment-related mortality (RR 0.53; 95% CI, 0.20-1.37; low certainty). Overall, the available evidence suggests with low certainty that rituximab in combination with methotrexate-based chemotherapy may improve progression-free survival in immunocompetent patients with newly diagnosed PCNSL, the pooled effect estimates did not show evidence for improvement of overall survival.

Knee arthroscopy versus conservative management in patients with degenerative knee disease: a systematic review.

OBJECTIVE: To determine the effects and complications of arthroscopic surgery compared with conservative management strategies in patients with degenerative knee disease. DESIGN: Systematic review. MAIN OUTCOME MEASURES: Pain, function, adverse events. DATA SOURCES: MEDLINE, EMBASE, the Cochrane Central Register of Controlled Trials (CENTRAL), Google Scholar and Open Grey up to August 2016. ELIGIBILITY CRITERIA: For effects, randomised clinical trials (RCTs) comparing arthroscopic surgery with a conservative management strategy (including sham surgery) in patients with degenerative knee disease. For complications, RCTs and observational studies. REVIEW METHODS: Two reviewers independently extracted data and assessed risk of bias for patient-important outcomes. A parallel guideline committee (BMJ Rapid Recommendations) provided input on the design and interpretation of the systematic review, including selection of patient-important outcomes. We used the GRADE approach to rate the certainty (quality) of the evidence. RESULTS: We included 13 RCTs and 12 observational studies. With respect to pain, the review identified high-certainty evidence that knee arthroscopy results in a very small reduction in pain up to 3 months (mean difference =5.4 on a 100-point scale, 95% CI 2.0 to 8.8) and very small or no pain reduction up to 2 years (mean difference =3.1, 95% CI -0.2 to 6.4) when compared with conservative management. With respect to function, the review identified moderate-certainty evidence that knee arthroscopy results in a very small improvement in the short term (mean difference =4.9 on a 100-point scale, 95% CI 1.5 to 8.4) and very small or no improved function up to 2 years (mean difference =3.2, 95% CI -0.5 to 6.8). Alternative presentations of magnitude of effect, and associated sensitivity analyses, were consistent with the findings of the primary analysis. Low-quality evidence suggested a very low probability of serious complications after knee arthroscopy. CONCLUSIONS: Over the long term, patients who undergo knee arthroscopy versus those who receive conservative management strategies do not have important benefits in pain or function. TRIAL REGISTRATION NUMBER: PROSPERO CRD42016046242.

Comparative effectiveness of tenofovir in HIV-infected treatment-experienced patients: systematic review and meta-analysis.

BACKGROUND: Antiretroviral therapy (ART) regimens for HIV infection are frequently changed. We conducted a systematic review of randomized trials (RCTs) on the benefits and harms of switching to tenofovir disoproxil fumarate (TDF)-based regimens in ART-experienced patients. METHODS: We included RCTs in HIV-infected adults comparing switching to a TDF-containing regimen with maintaining or switching to another regimen. We searched MEDLINE, EMBASE, CENTRAL, LILACS, SCI, and the WHO Global Health Library. We assessed bias with the Cochrane tool and synthesized data using random-effects meta-analyses and Peto's approach. For further analyses, we added data from a previous systematic review in treatment-naïve patients. RESULTS: 17 RCTs with 2210 patients were included. All but one study had a high risk of bias. There was no significant association of switching to TDF-based regimens with mortality, fractures, CD4-cell count, body fat, virological failure, LDL-, and HDL-cholesterol. TDF-based regimens decreased total cholesterol (mean difference -12.05 mg/dL; 95% CI -20.76 to -3.34), trigylcerides (-14.33 mg/dL; -23.73 to -4.93), and bone mineral density (BMD; hip: -2.46%; -3.9 to -1.03; lumbar spine -1.52%; -2.69 to -0.34). Effects on estimated glomerular filtration (eGFR) were inconsistent and depended on the measurement. Adding 22 RCTs from 8297 treatment-naïve patients gave consistent results with then significant reductions of LDL (-7.57 mg/dL; -10.37 to -4.78), HDL (-2.38 mg/dL; -3.83 to -0.93), and eGFR (-3.49 ml/min; -5.56 to -1.43). CONCLUSIONS: Switching to TDF-based regimens is associated with reductions of BMD and lipid levels and possibly lowered kidney function. The evidence is limited by the high risk of bias.

Reporting of IMMPACT-recommended core outcome domains among trials assessing opioids for chronic non-cancer pain.

The Initiative on Methods, Measurement, and Pain Assessment in Clinical Trials (IMMPACT) has recommended that trialists evaluating treatments for chronic pain should consider reporting 9 patient-important outcome domains. We examined the extent to which clinical trials evaluating the effect of opioids for chronic non-cancer pain (CNCP) report outcome domains recommended by IMMPACT. We systematically searched electronic databases for English-language studies that randomized patients with CNCP to receive an opioid or a non-opioid control. In duplicate and independently, reviewers established the eligibility of each identified study and recorded all reported outcome domains from eligible trials. We conducted a priori regression analyses to explore factors that may be associated with IMMPACT-recommended outcome domains. Among 156 eligible trials, reporting of IMMPACT-recommended outcome domains was highly variable, ranging from 99% for pain to 7% for interpersonal functioning. Recently published trials were more likely to report the effect of treatment on physical functioning, emotional functioning, role functioning, sleep and fatigue, and participant disposition. Trials for which the corresponding author was from North America were more likely to report treatment effects on physical functioning and participant ratings of improvement and satisfaction with treatment. Trials published in higher impact journals were more likely to report treatment effects on emotional function, but less likely to report participant ratings of improvement and satisfaction with treatment. Most IMMPACT domains showed an increased rate of reporting over time, although many patient-important outcome domains remained unreported by over half of all trials evaluating the effects of opioids for CNCP.

Completion and Publication Rates of Randomized Controlled Trials in Surgery: An Empirical Study.

OBJECTIVE: To investigate the prevalence of discontinuation and nonpublication of surgical versus medical randomized controlled trials (RCTs) and to explore risk factors for discontinuation and nonpublication of surgical RCTs. BACKGROUND: Trial discontinuation has significant scientific, ethical, and economic implications. To date, the prevalence of discontinuation of surgical RCTs is unknown. METHODS: All RCT protocols approved between 2000 and 2003 by 6 ethics committees in Canada, Germany, and Switzerland were screened. Baseline characteristics were collected and, if published, full reports retrieved. Risk factors for early discontinuation for slow recruitment and nonpublication were explored using multivariable logistic regression analyses. RESULTS: In total, 863 RCT protocols involving adult patients were identified, 127 in surgery (15%) and 736 in medicine (85%). Surgical trials were discontinued for any reason more often than medical trials [43% vs 27%, risk difference 16% (95% confidence interval [CI]: 5%-26%); P = 0.001] and more often discontinued for slow recruitment [18% vs 11%, risk difference 8% (95% CI: 0.1%-16%); P = 0.020]. The percentage of trials not published as full journal article was similar in surgical and medical trials (44% vs 40%, risk difference 4% (95% CI: -5% to 14%); P = 0.373). Discontinuation of surgical trials was a strong risk factor for nonpublication (odds ratio = 4.18, 95% CI: 1.45-12.06; P = 0.008). CONCLUSIONS: Discontinuation and nonpublication rates were substantial in surgical RCTs and trial discontinuation was strongly associated with nonpublication. These findings need to be taken into account when interpreting surgical literature. Surgical trialists should consider feasibility studies before embarking on full-scale trials.

Opioids for chronic non-cancer pain: a protocol for a systematic review of randomized controlled trials.

BACKGROUND: Opioids are prescribed frequently and increasingly for the management of chronic non-cancer pain (CNCP). Current systematic reviews have a number of limitations, leaving uncertainty with regard to the benefits and harms associated with opioid therapy for CNCP. We propose to conduct a systematic review and meta-analysis to summarize the evidence for using opioids in the treatment of CNCP and the risk of associated adverse events. METHODS AND DESIGN: Eligible trials will include those that randomly allocate patients with CNCP to treatment with any opioid or any non-opioid control group. We will use the guidelines published by the Initiative on Methods, Measurement, and Pain Assessment in Clinical Trials (IMMPACT) to inform the outcomes that we collect and present. We will use the Grading of Recommendations, Assessment, Development and Evaluation (GRADE) system to evaluate confidence in the evidence on an outcome-by-outcome basis. Teams of reviewers will independently and in duplicate assess trial eligibility, abstract data, and assess risk of bias among eligible trials. To ensure interpretability of our results, we will present risk differences and measures of relative effect for all outcomes reported and these will be based on anchor-based minimally important clinical differences, when available. We will conduct a priori defined subgroup analyses consistent with current best practices. DISCUSSION: Our review will evaluate both the effectiveness and the adverse events associated with opioid use for CNCP, evaluate confidence in the evidence using the GRADE approach, and prioritize patient-important outcomes with a focus on functional gains guided by IMMPACT recommendations. Our results will facilitate evidence-based management of patients with CNCP and identify key areas for future research. TRIAL REGISTRATION: Our protocol is registered on PROSPERO (CRD42012003023), http://www.crd.york.ac.uk/PROSPERO.

Systematic review and network meta-analysis of interventions for fibromyalgia: a protocol.

BACKGROUND: Fibromyalgia is associated with substantial socioeconomic loss and, despite considerable research including numerous randomized controlled trials (RCTs) and systematic reviews, there exists uncertainty regarding what treatments are effective. No review has evaluated all interventional studies for fibromyalgia, which limits attempts to make inferences regarding the relative effectiveness of treatments. METHODS/DESIGN: We will conduct a network meta-analysis of all RCTs evaluating therapies for fibromyalgia to determine which therapies show evidence of effectiveness, and the relative effectiveness of these treatments. We will acquire eligible studies through a systematic search of CINAHL, EMBASE, MEDLINE, AMED, HealthSTAR, PsychINFO, PapersFirst, ProceedingsFirst, and the Cochrane Central Registry of Controlled Trials. Eligible studies will randomly allocate patients presenting with fibromyalgia or a related condition to an intervention or a control. Teams of reviewers will, independently and in duplicate, screen titles and abstracts and complete full text reviews to determine eligibility, and subsequently perform data abstraction and assess risk of bias of eligible trials. We will conduct meta-analyses to establish the effect of all reported therapies on patient-important outcomes when possible. To assess relative effects of treatments, we will construct a random effects model within the Bayesian framework using Markov chain Monte Carlo methods. DISCUSSION: Our review will be the first to evaluate all treatments for fibromyalgia, provide relative effectiveness of treatments, and prioritize patient-important outcomes with a focus on functional gains. Our review will facilitate evidence-based management of patients with fibromyalgia, identify key areas for future research, and provide a framework for conducting large systematic reviews involving indirect comparisons.

Chronic renal failure and proteinuria in adulthood: Fabry disease predominantly affecting the kidneys.

The prognosis of Fabry disease has changed since enzyme-replacement treatment was introduced. Therefore, early diagnosis is instrumental. We describe a family presenting with chronic renal failure and proteinuria in which classic skin and neurological features were absent and the diagnosis of Fabry disease was difficult and not established until a second family member developed renal abnormalities. A 35-year-old man was admitted because he was overweight and had hypertension, with a serum creatinine level of 1.3 mg/dL (115 micromol/L) and protein excretion of 870 mg/d. Because 1 brother, who died years ago at the age of 32 years of acute myeloid leukemia, also had chronic renal failure and proteinuria, the diagnosis of Fabry disease was entertained. In the index patient, acroparesthesia, hypohidrosis, pain, angiokeratomas of the skin, and cornea verticillata suggesting Fabry disease were absent. Conversely, renal biopsy showed typical globotriaosylceramide deposits, and leukocyte alpha-galactosidase (alpha-GLA) A activity was decreased. Analysis of the alpha-GLA gene showed the mutation E66K. The mutation also was found in another asymptomatic 30-year-old brother who also had chronic renal failure and proteinuria, but normal extrarenal findings. In the brother who died, Fabry disease, missed at autopsy because of cancer-related findings, could be confirmed after repeated review of histological slides. Mutation carriers also included the mother, a sister (both without abnormalities), and a nephew (with episodic pains in his feet). We conclude that familial chronic renal failure combined with proteinuria is suggestive of Fabry disease, and such specific mutations as E66K predominantly may affect the kidneys.