Publications
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Cro S, Morris TP, Roger JH, et al., 2024, Comments on ‘standard and reference‐based conditional mean imputation’: Regulators and trial statisticians be aware!, Pharmaceutical Statistics, ISSN: 1539-1604
<jats:title>Abstract</jats:title><jats:p>Accurate frequentist performance of a method is desirable in confirmatory clinical trials, but is not sufficient on its own to justify the use of a missing data method. Reference‐based <jats:italic>conditional mean</jats:italic> imputation, with variance estimation justified solely by its frequentist performance, has the surprising and undesirable property that the estimated variance becomes smaller the greater the number of missing observations; as explained under jump‐to‐reference it effectively forces the true treatment effect to be <jats:italic>exactly</jats:italic> zero for patients with missing data.</jats:p>
Casswell EJ, Cro S, Cornelius VR, et al., 2024, Randomised controlled trial of adjunctive triamcinolone acetonide in eyes undergoing vitreoretinal surgery following open globe trauma: the ASCOT study, British Journal of Ophthalmology, Vol: 108, Pages: 440-448, ISSN: 0007-1161
BACKGROUND/AIMS: To investigate the clinical effectiveness of adjunctive triamcinolone acetonide (TA) given at the time of vitreoretinal surgery following open globe trauma (OGT). METHODS: A phase 3, multicentre, double-masked randomised controlled trial of patients undergoing vitrectomy following OGT comparing adjunctive TA (intravitreal and subtenons) against standard care (2014-2020). The primary outcome was the proportion of patients with at least 10 Early Treatment Diabetic Retinopathy Study (ETDRS) letter improvement in corrected visual acuity (VA) at 6 months. Secondary outcomes included: change in ETDRS, retinal detachment (RD) secondary to PVR, retinal reattachment, macular reattachment, tractional RD, number of operations, hypotony, elevated intraocular pressure and quality of life. RESULTS: 280 patients were randomised over 75 months, of which 259 completed the study. 46.9% (n=61/130) of patients in the treatment group had a 10-letter improvement in VA compared with 43.4% (n=56/129) of the control group (difference 3.5% (95% CI -8.6% to 15.6%), OR=1.03 (95% CI 0.61 to 1.75), p=0.908)). Secondary outcome measures also failed to show any treatment benefit. For two of the secondary outcome measures, stable complete retinal and macular reattachment, outcomes were worse in the treatment group compared with controls, respectively, 51.6% (n=65/126) vs 64.2% (n=79/123), OR=0.59 (95% CI 0.36 to 0.99), and 54.0% (n=68/126) vs 66.7% (n=82/123), OR=0.59 (95% CI 0.35 to 0.98), for TA vs control. CONCLUSION: The use of combined intraocular and sub-Tenons capsule TA is not recommended as an adjunct to vitrectomy surgery following OGT. TRIAL REGISTRATION NUMBER: NCT02873026.
Kahan BC, Morris TP, Cro S, 2024, We must let the research question drive study methods., BMJ, Vol: 384
Kahan B, Hindley J, Edwards M, et al., 2024, The estimands framework: a primer on the ICH E9(R1) addendum, BMJ: British Medical Journal, Vol: 384, ISSN: 0959-535X
Estimands can be used in studies of healthcare interventions to clarify the interpretation of treatment effects. The addendum to the ICH E9 harmonised guideline on statistical principles for clinical trials (ICH E9(R1)) describes a framework for using estimands as part of a study. This paper provides an overview of the estimands framework, as outlined in the addendum, with the aim of explaining why estimands are beneficial; clarifying the terminology being used; and providing practical guidance on using estimands to decide the appropriate study design, data collection, and estimation methods. This article illustrates how to use the estimands framework by applying it to an ongoing trial in emergency bowel surgery. Estimands can be a useful way of clarifying the exact research question being evaluated in a study, both to avoid misinterpretation and to ensure that study methods are aligned to the overall study objectives.
Morris TP, White IR, Cro S, et al., 2024, Comment on Oberman & Vink: Should we fix or simulate the complete data in simulation studies evaluating missing data methods?, Biometrical Journal: journal of mathematical methods in biosciences, Vol: 66, ISSN: 0323-3847
For simulation studies that evaluate methods of handling missing data, we argue that generating partially observed data by fixing the complete data and repeatedly simulating the missingness indicators is a superficially attractive idea but only rarely appropriate to use.
Rehal S, Cro S, Phillips P, et al., 2023, Handling intercurrent events and missing data in non-inferiority trials using the estimand framework: a tuberculosis case study, Clinical Trials, Vol: 20, Pages: 457-582, ISSN: 1740-7745
IntroductionThe ICH E9 addendum outlining the estimand framework for clinical trials was published in 2019 but provides limited guidance around how to handle intercurrent events for non-inferiority studies. Once an estimand is defined, it is also unclear how to deal with missing values using principled analyses for non-inferiority studies.MethodsUsing a tuberculosis clinical trial as a case study, we propose a primary estimand, and an additional estimand suitable for non-inferiority studies. For estimation, multiple imputation methods that align with the estimands for both primary and sensitivity analysis are proposed. We demonstrate estimation methods using the twofold fully conditional specification multiple imputation algorithm and then extend and use reference-based multiple imputation for a binary outcome to target the relevant estimands, proposing sensitivity analyses under each. We compare the results from using these multiple imputation methods with those from the original study.ResultsConsistent with the ICH E9 addendum, estimands can be constructed for a non-inferiority trial which improves on the per-protocol/intention-to-treat-type analysis population previously advocated, involving respectively a hypothetical or treatment policy strategy to handle relevant intercurrent events. Results from using the ‘twofold’ multiple imputation approach to estimate the primary hypothetical estimand, and using reference-based methods for an additional treatment policy estimand, including sensitivity analyses to handle the missing data, were consistent with the original study’s reported per-protocol and intention-to-treat analysis in failing to demonstrate non-inferiority.ConclusionsUsing carefully constructed estimands and appropriate primary and sensitivity estimators, using all the information available, results in a more principled and statistically rigorous approach to analysis. Doing so provides an accurate interpretation of the estimand.
Cro S, Kahan B, Patel A, et al., 2023, Starting a conversation about estimands with public partners involved in clinical trials: a co-developed tool, Trials, Vol: 24, ISSN: 1745-6215
Background:Clinical trials aim to draw conclusions about the effects of treatments, but a trial can address many different potential questions. For example, does the treatment work well for patients who take it as prescribed? Or does it work regardless of whether patients take it exactly as prescribed? Since different questions can lead to different conclusions on treatment benefit, it is important to clearly understand what treatment effect a trial aims to investigate—this is called the ‘estimand’. Using estimands helps to ensure trials are designed and analysed to answer the questions of interest to different stakeholders, including patients and public. However, there is uncertainty about whether patients and public would like to be involved in defining estimands and how to do so. Public partners are patients and/or members of the public who are part of, or advise, the research team. We aimed to (i) co-develop a tool with public partners that helps explain what an estimand is and (ii) explore public partner’s perspectives on the importance of discussing estimands during trial design.Methods:An online consultation meeting was held with 5 public partners of mixed age, gender and ethnicities, from various regions of the UK. Public partner opinions were collected and a practical tool describing estimands, drafted before the meeting by the research team, was developed. Afterwards, the tool was refined, and additional feedback sought via email.Results:Public partners want to be involved in estimand discussions. They found an introductory tool, to be presented and described to them by a researcher, helpful for starting a discussion about estimands in a trial design context. They recommended storytelling, analogies and visual aids within the tool. Four topics related to public partners’ involvement in defining estimands were identified: (i) the importance of addressing questions that are relevant to patients and public in trials, (ii) involvi
Charteris DG, Cro S, Casswell E, et al., 2023, A randomised controlled trial of adjunctive triamcinolone acetonide in eyes undergoing vitreoretinal surgery for open globe trauma – the ASCOT study, Health Technology Assessment, Vol: 27, Pages: 1-50, ISSN: 1366-5278
Background: Eyes sustaining open globe trauma are at high risk of severe visual impairment. Proliferative vitreoretinopathy is the most common cause of retinal detachment and visual loss in eyes with open globe trauma. There is evidence from experimental studies and pilot clinical trials that the use of adjunctive steroid medication triamcinolone acetonide can reduce the incidence of proliferative vitreoretinopathy and improve outcomes of surgery for open globe trauma. Objective: The Adjunctive Steroid Combination in Ocular Trauma or ASCOT study aimed to investigate the clinical effectiveness of adjunctive triamcinolone acetonide given at the time of vitreoretinal surgery for open globe trauma. Design: A phase 3 multicentre double-masked randomised controlled trial randomising patients undergoing vitrectomy following open globe trauma to either adjunctive triamcinolone acetonide or standard care. Setting: Hospital vitreoretinal surgical services dealing with open globe trauma. Participants: Patients undergoing vitrectomy surgery who had sustained open globe trauma. Interventions: Triamcinolone acetonide 4 mg/0.1 ml into the vitreous cavity and 40 mg/1 ml sub-Tenon’s or standard vitreoretinal surgery and postoperative care. Main outcome measures: The primary outcome was the proportion of patients with at least 10 letters of improvement in corrected visual acuity at six months. Secondary outcomes included retinal detachment secondary to proliferative vitreoretinopathy, retinal reattachment, macula reattachment, tractional retinal detachment, number of operations, hypotony, elevated intraocular pressure and quality of life. Health-related quality of life was assessed using the EuroQol Five Domain and Visual Function Questionnaire 25 questionnaires.Results: A total of 280 patients were randomised; 129 were analysed from the control group and 130 from the treatment group. The treatment group appeared, by chance, to have more severe pathology on presentation. The pr
Kahan B, Cro S, Li F, et al., 2023, Eliminating ambiguous treatment effects using estimands, American Journal of Epidemiology, Vol: 192, Pages: 987-984, ISSN: 0002-9262
Most reported treatment effects in medical research studies are ambiguously defined, which can lead to misinterpretation of study results. This is because most studies do not attempt to describe what the treatment effect represents, and instead require readers to deduce this based on the reported statistical methods. However, this approach is fraught, as many methods provide counterintuitive results. For example, some methods include data from all patients, yet the resulting treatment effect applies only to a subset of patients, whereas other methods will exclude certain patients while results will apply to everyone. Additionally, some analyses provide estimates pertaining to hypothetical settings where patients never die or discontinue treatment. Herein we introduce estimands as a solution to the aforementioned problem. An estimand is a clear description of what the treatment effect represents, thus saving readers the necessity of trying to infer this from study methods and potentially getting it wrong. We provide examples of how estimands can remove ambiguity from reported treatment effects and describe their current use in practice. The crux of our argument is that readers should not have to infer what investigators are estimating; they should be told explicitly.
Cro S, Partington G, Cornelius VR, et al., 2023, Presenting clinical characteristics of open globe injuries in ocular trauma: baseline analysis of cases in the ASCOT national clinical trial, Eye, Vol: 37, Pages: 1732-1740, ISSN: 0950-222X
Background/ObjectivesThe Adjunctive Steroid Combination in Ocular Trauma (ASCOT) trial is a unique pragmatic, multi-centre, patient and assessor masked, randomised controlled trial. We evaluate the clinical characteristics and pathology of this large trial cohort of patients with open globe injuries undergoing vitreoretinal surgery, including the associations between patient characteristics and their baseline vision.Subjects/MethodsWe (i) summarise demographics, injury history and ocular history of the 280 participants recruited into the ASCOT trial using descriptive statistics; (ii) analyse the national and seasonal variation across England and Scotland in these participant characteristics; and (iii) explore the associations between participant demographic, trauma history, ocular history and presenting baseline visual acuity (measured using the Early Treatment Diabetic Retinopathy Study, ETDRS) using multivariable regression analyses.ResultsThe majority of participants with open globe penetrating injuries were of white ethnicity (233, 84%), male (246, 88%), with a median age of 43 years (IQR 30–55 years). There was considerable variability in presenting visual acuity with 75% unable to read any letters on the ETDRS chart, whilst the median ETDRS letter score was 58 (IQR 24–80) for those who could read ≥1 letter. The most common causes of injury were workplace related (31%) or interpersonal violence (24%). Previous eye surgery, visual axis corneal scar, lens status, hyphaemia and vitreous haemorrhaging were found to be associated with presenting vision as measured by the ETDRS chart.ConclusionThe ASCOT trial provides valuable insights into the spectrum of pathology of patients with open globe eye injuries undergoing vitreoretinal surgery. The identified causes of injury and clinical presentation of the cases will help in training and resource planning to deal with these often challenging surgical cases.Trial registrationEudraCT No. 014-002193-37. HTA
Turner RM, Clements MN, Quartagno M, et al., 2023, Practical approaches to Bayesian sample size determination in non-inferiority trials with binary outcomes, Statistics in Medicine, Vol: 42, Pages: 1127-1138, ISSN: 0277-6715
Bayesian analysis of a non-inferiority trial is advantageous in allowing direct probability statements to be made about the relative treatment difference rather than relying on an arbitrary and often poorly justified non-inferiority margin. When the primary analysis will be Bayesian, a Bayesian approach to sample size determination will often be appropriate for consistency with the analysis. We demonstrate three Bayesian approaches to choosing sample size for non-inferiority trials with binary outcomes and review their advantages and disadvantages. First, we present a predictive power approach for determining sample size using the probability that the trial will produce a convincing result in the final analysis. Next, we determine sample size by considering the expected posterior probability of non-inferiority in the trial. Finally, we demonstrate a precision-based approach. We apply these methods to a non-inferiority trial in antiretroviral therapy for treatment of HIV-infected children. A predictive power approach would be most accessible in practical settings, because it is analogous to the standard frequentist approach. Sample sizes are larger than with frequentist calculations unless an informative analysis prior is specified, because appropriate allowance is made for uncertainty in the assumed design parameters, ignored in frequentist calculations. An expected posterior probability approach will lead to a smaller sample size and is appropriate when the focus is on estimating posterior probability rather than on testing. A precision-based approach would be useful when sample size is restricted by limits on recruitment or costs, but it would be difficult to decide on sample size using this approach alone.
Shariq S, Cardoso Pinto AM, Budhathoki SS, et al., 2023, Barriers and facilitators to the recruitment of disabled people to clinical trials: a scoping review, Trials, Vol: 24, Pages: 1-13, ISSN: 1745-6215
IntroductionUnderrepresentation of disabled groups in clinical trials results in an inadequate evidence base for their clinical care, which drives health inequalities. This study aims to review and map the potential barriers and facilitators to the recruitment of disabled people in clinical trials to identify knowledge gaps and areas for further extensive research. The review addresses the question: ‘What are the barriers and facilitators to recruitment of disabled people to clinical trials?’.MethodsThe Joanna Briggs Institute (JBI) Scoping review guidelines were followed to complete the current scoping review. MEDLINE and EMBASE databases were searched via Ovid. The literature search was guided by a combination of four key concepts from the research question: (1) disabled populations, (2) patient recruitment, (3) barriers and facilitators, and (4) clinical trials. Papers discussing barriers and facilitators of all types were included. Papers that did not have at least one disabled group as their population were excluded. Data on study characteristics and identified barriers and facilitators were extracted. Identified barriers and facilitators were then synthesised according to common themes.ResultsThe review included 56 eligible papers. The evidence on barriers and facilitators was largely sourced from Short Communications from Researcher Perspectives (N = 22) and Primary Quantitative Research (N = 17). Carer perspectives were rarely represented in articles. The most common disability types for the population of interest in the literature were neurological and psychiatric disabilities. A total of five emergent themes were determined across the barriers and facilitators. These were as follows: risk vs benefit assessment, design and management of recruitment protocol, balancing internal and external validity considerations, consent and ethics, and systemic factors.ConclusionsBoth barriers and facilitators were often highly spec
Van Lancker K, Tarima S, Bartlett J, et al., 2023, Rejoinder: estimands and their estimators for clinical trials impacted by the COVID-19 pandemic: a report from the NISS ingram Olkin forum series on unplanned clinical trial disruptions, Statistics in Biopharmaceutical Research, Vol: 15, Pages: 119-124, ISSN: 1946-6315
Van Lancker K, Tarima S, Bartlett J, et al., 2023, Estimands and their estimators for clinical trials impacted by the COVID-19 pandemic: a report from the NISS Ingram Olkin Forum Series on unplanned clinical trial disruptions, Statistics in Biopharmaceutical Research, Vol: 15, Pages: 94-111, ISSN: 1946-6315
The COVID-19 pandemic continues to affect the conduct of clinical trials globally. Complications may arise from pandemic-related operational challenges such as site closures, travel limitations and interruptions to the supply chain for the investigational product, or from health-related challenges such as COVID-19 infections. Some of these complications lead to unforeseen intercurrent events in the sense that they affect either the interpretation or the existence of the measurements associated with the clinical question of interest. In this article, we demonstrate how the ICH E9(R1) Addendum on estimands and sensitivity analyses provides a rigorous basis to discuss potential pandemic-related trial disruptions and to embed these disruptions in the context of study objectives and design elements. We introduce several hypothetical estimand strategies and review various causal inference and missing data methods, as well as a statistical method that combines unbiased and possibly biased estimators for estimation. To illustrate, we describe the features of a stylized trial, and how it may have been impacted by the pandemic. This stylized trial will then be re-visited by discussing the changes to the estimand and the estimator to account for pandemic disruptions. Finally, we outline considerations for designing future trials in the context of unforeseen disruptions.
Kelleher MM, Phillips R, Brown SJ, et al., 2022, Skin care interventions in infants for preventing eczema and food allergy., Cochrane Database of Systematic Reviews, Vol: 11, Pages: 1-177, ISSN: 1469-493X
BACKGROUND: Eczema and food allergy are common health conditions that usually begin in early childhood and often occur in the same people. They can be associated with an impaired skin barrier in early infancy. It is unclear whether trying to prevent or reverse an impaired skin barrier soon after birth is effective for preventing eczema or food allergy. OBJECTIVES: Primary objective To assess the effects of skin care interventions such as emollients for primary prevention of eczema and food allergy in infants. Secondary objective To identify features of study populations such as age, hereditary risk, and adherence to interventions that are associated with the greatest treatment benefit or harm for both eczema and food allergy. SEARCH METHODS: We performed an updated search of the Cochrane Skin Specialised Register, CENTRAL, MEDLINE, and Embase in September 2021. We searched two trials registers in July 2021. We checked the reference lists of included studies and relevant systematic reviews, and scanned conference proceedings to identify further references to relevant randomised controlled trials (RCTs). SELECTION CRITERIA: We included RCTs of skin care interventions that could potentially enhance skin barrier function, reduce dryness, or reduce subclinical inflammation in healthy term (> 37 weeks) infants (≤ 12 months) without pre-existing eczema, food allergy, or other skin condition. Eligible comparisons were standard care in the locality or no treatment. Types of skin care interventions could include moisturisers/emollients; bathing products; advice regarding reducing soap exposure and bathing frequency; and use of water softeners. No minimum follow-up was required. DATA COLLECTION AND ANALYSIS: This is a prospective individual participant data (IPD) meta-analysis. We used standard Cochrane methodological procedures, and primary analyses used the IPD dataset. Primary outcomes wer
Paterson L, Lingford-Hughes A, Cro S, et al., 2022, FORWARDS-1; An adaptive, single-blind, placebo-controlled ascending dose study of acute baclofen on safety parameters in opioid dependence during methadone-maintenance treatment; a pharmacokinetic-pharmacodynamic study, Trials, Vol: 23, ISSN: 1745-6215
Background:Treatment of opiate addiction with opiate substitution treatment (e.g. methadone) is beneficial. However, some individuals desire or would benefit from abstinence but there are limited options to attenuate problems with opiate withdrawal. Preclinical and preliminary clinical evidence suggests that the GABA-B agonist, baclofen, has the desired properties to facilitate opiate detoxification and prevent relapse. This study aims to understand whether there are any safety issues in administering baclofen to opioid-dependent individuals receiving methadone.Methods:Opiate-dependent individuals (DSM-5 severe opioid use disorder) maintained on methadone will be recruited from addiction services in northwest London (NHS and third sector providers). Participants will be medically healthy with no severe chronic obstructive pulmonary disease or type 2 respiratory failure, no current dependence on other substances (excluding nicotine), no current severe DSM-5 psychiatric disorders, and no contraindications for baclofen or 4800 IU vitamin D (placebo). Eligible participants will be randomised in a 3:1 ratio to receive baclofen or placebo in an adaptive, single-blind, ascending dose design. A Bayesian dose-escalation model will inform the baclofen dose (10, 30, 60, or 90 mg) based on the incidence of ‘dose-limiting toxicity’ (DLT) events and participant-specific methadone dose. A range of respiratory, cardiovascular, and sedative measures including the National Early Warning Score (NEWS2) and Glasgow Coma Scale will determine DLT. On the experimental day, participants will consume their usual daily dose of methadone followed by an acute dose of baclofen or placebo (vitamin D3) ~ 1 h later. Measures including oxygen saturation, transcutaneous CO2, respiratory rate, QTc interval, subjective effects (sedation, drug liking, craving), plasma levels (baclofen, methadone), and adverse events will be obtained using validated questionnaires and examinations periodicall
Cro S, 2022, Time to improve the clarity of clinical trial reports by including estimands., BMJ, Vol: 378, Pages: 1-2, ISSN: 0966-6494
Cro S, Kahan BC, Rehal S, et al., 2022, Evaluating how clear the questions being investigated in randomised trials are: systematic review of estimands., BMJ, Vol: 378
OBJECTIVES: To evaluate how often the precise research question being addressed about an intervention (the estimand) is stated or can be determined from reported methods, and to identify what types of questions are being investigated in phase 2-4 randomised trials. DESIGN: Systematic review of the clarity of research questions being investigated in randomised trials in 2020 in six leading general medical journals. DATA SOURCE: PubMed search in February 2021. ELIGIBILITY CRITERIA FOR SELECTING STUDIES: Phase 2-4 randomised trials, with no restrictions on medical conditions or interventions. Cluster randomised, crossover, non-inferiority, and equivalence trials were excluded. MAIN OUTCOME MEASURES: Number of trials that stated the precise primary question being addressed about an intervention (ie, the primary estimand), or for which the primary estimand could be determined unambiguously from the reported methods using statistical knowledge. Strategies used to handle post-randomisation events that affect the interpretation or existence of patient outcomes, such as intervention discontinuations or uses of additional drug treatments (known as intercurrent events), and the corresponding types of questions being investigated. RESULTS: 255 eligible randomised trials were identified. No trials clearly stated all the attributes of the estimand. In 117 (46%) of 255 trials, the primary estimand could be determined from the reported methods. Intercurrent events were reported in 242 (95%) of 255 trials; but the handling of these could only be determined in 125 (49%) of 255 trials. Most trials that provided this information considered the occurrence of intercurrent events as irrelevant in the calculation of the treatment effect and assessed the effect of the intervention regardless (96/125, 77%)-that is, they used a treatment policy strategy. Four (4%) of 99 trials with treatment non-adherence owing to adverse events estimated the treatment effect in a hypothetical setting (ie, th
Campbell D, McDonald C, Cro S, et al., 2022, Access to unpublished protocols and statistical analysis plans of randomised trials, Trials, Vol: 23, ISSN: 1745-6215
Background:Access to protocols and statistical analysis plans (SAPs) increases the transparency of randomised trial by allowing readers to identify and interpret unplanned changes to study methods, however they are often not made publicly available. We sought to determine how often study investigators would share unavailable documents upon request.Methods:We used trials from two previously identified cohorts (cohort 1: 101 trials published in high impact factor journals between January and April of 2018; cohort 2: 100 trials published in June 2018 in journals indexed in PubMed) to determine whether study investigators would share unavailable protocols/SAPs upon request. We emailed corresponding authors of trials with no publicly available protocol or SAP up to four times.Results:Overall, 96 of 201 trials (48%) across the two cohorts had no publicly available protocol or SAP (11/101 high-impact cohort, 85/100 PubMed cohort). In total, 8/96 authors (8%) shared some trial documentation (protocol only [n = 5]; protocol and SAP [n = 1]; excerpt from protocol [n = 1]; research ethics application form [n = 1]). We received protocols for 6/96 trials (6%), and a SAP for 1/96 trial (1%). Seventy-three authors (76%) did not respond, 7 authors responded (7%) but declined to share a protocol or SAP, and eight email addresses were invalid (8%). A total of 329 emails were sent (an average of 41 emails for every trial which sent documentation). After emailing authors, the total number of trials with an available protocol increased by only 3%, from 52% in to 55%.Conclusions:Most study investigators did not share their unpublished protocols or SAPs upon direct request. Alternative strategies are needed to increase transparency of randomised trials and ensure access to protocols and SAPs.
Lin Q, Ye T, Ye P, et al., 2022, Hypertension in stroke survivors and associations with national premature stroke mortality: data on 2.5 million participants from multinational screening campaigns., The Lancet Global Health, Vol: 10, Pages: e1141-e1149, ISSN: 2214-109X
BackgroundBlood pressure (BP) control plays a pivotal role in reducing stroke incidence and recurrence. May Measurement Month (MMM) is the largest global BP screening campaign, initiated in 2017 by the International Society of Hypertension (ISH). We aim to compare MMM participants with and without a previous stroke and to investigate associations between national-level estimates of BP management from MMM and premature stroke mortality.MethodsOver 2.5 million volunteers (≥18 years) were screened in May 2017 and 2018 from 92 countries. Three seated BPs and demographic, lifestyle, and cardiovascular disease data were collected. Associations between risk factors and stroke history were analysed using mixed-effects logistic regression. Linear regression was used to investigate associations between national-level estimates of BP management and premature stroke mortality based on Global Burden of Diseases (GBD) data. FindingsOf 2 222 399 (88·4%) participants with recorded data on a history of stroke, 62 639 (2·8%) reported a previous stroke. Those with a stroke history had higher rates of hypertension and treated and controlled hypertension than those without. One third of those with a stroke history had untreated or treated but uncontrolled BP (≥140/90 mmHg). Strong positive associations were found between national premature stroke mortality and increasing mean systolic BP levels and proportion of participants with raised BP and strong negative associations with the proportions of hypertensives on treatment and with controlled BP. InterpretationBP control remains suboptimal worldwide amongst those with a previous stroke. National estimates of BP management reflect national premature stroke mortality sufficiently well to provide a prompt for policymakers to promote BP screening and management.
Clements MN, White IR, Copas AJ, et al., 2022, Improving clinical trial interpretation with ACCEPT analyses, NEJM Evidence, Vol: 1, ISSN: 2766-5526
Kelleher MM, Cro S, Phillips R, et al., 2022, Correspondence to " Emollients in infancy to prevent atopic dermatitis: A systematic review and meta-analysis", Allergy, Vol: 77, Pages: 1931-1933, ISSN: 0105-4538
Phillips R, Cro S, Wheeler G, et al., 2022, Visualising harms in publications of randomised controlled trials: consensus and recommendations, BMJ: British Medical Journal, Vol: 377, ISSN: 0959-535X
Objective: To improve communication of harm in publications of randomised controlled trials via the development of recommendations for visually presenting harm outcomes.Design: Consensus study.Setting: 15 clinical trials units registered with the UK Clinical Research Collaboration, an academic population health department, Roche Products, and TheBMJ.Participants: Experts in clinical trials: 20 academic statisticians, one industry statistician, one academic health economist, one data graphics designer, and two clinicians.Main outcome measures: A methodological review of statistical methods identified visualisations along with those recommended by consensus group members. Consensus on visual recommendations was achieved (at least 60% of the available votes) over a series of three meetings with participants. The participants reviewed and critically appraised candidate visualisations against an agreed framework and voted on whether to endorse each visualisation. Scores marginally below this threshold (50-60%) were revisited for further discussions and votes retaken until consensus was reached.Results: 28 visualisations were considered, of which 10 are recommended for researchers to consider in publications of main research findings. The choice of visualisations to present will depend on outcome type (eg, binary, count, time-to-event, or continuous), and the scenario (eg, summarising multiple emerging events or one event of interest). A decision tree is presented to assist trialists in deciding which visualisations to use. Examples are provided of each endorsed visualisation, along with an example interpretation, potential limitations, and signposting to code for implementation across a range of standard statistical software. Clinician feedback was incorporated into the explanatory information provided in the recommendations to aid understanding and interpretation.Conclusions: Visualisations provide a powerful tool to communicate harms in clinical trials, offering an alt
Cro S, Smith CH, 2022, Response to: 'Anakinra for palmoplantar pustulosis: results from a randomized, double-blind, multicentre, two-staged, adaptive placebo-controlled trial (APRICOT)': reply from the authors, BRITISH JOURNAL OF DERMATOLOGY, Vol: 186, Pages: 909-910, ISSN: 0007-0963
Mozgunov P, Cro S, Lingford-Hughes A, et al., 2022, A dose-finding design for dual-agent trials with patient-specific doses for one agent with application to an opiate detoxification trial, Pharmaceutical Statistics: the journal of applied statistics in the pharmaceutical industry, Vol: 21, Pages: 476-495, ISSN: 1539-1604
There is a growing interest in early phase dose-finding clinical trials studying combinations of several treatments. While the majority of dose finding designs for such setting were proposed for oncology trials, the corresponding designs are also essential in other therapeutic areas. Furthermore, there is increased recognition of recommending the patient-specific doses/combinations, rather than a single target one that would be recommended to all patients in later phases regardless of their characteristics. In this paper, we propose a dose-finding design for a dual-agent combination trial motivated by an opiate detoxification trial. The distinguishing feature of the trial is that the (continuous) dose of one compound is defined externally by the clinicians and is individual for every patient. The objective of the trial is to define the dosing function that for each patient would recommend the optimal dosage of the second compound. Via a simulation study, we have found that the proposed design results in high accuracy of individual dose recommendation and is robust to the model misspecification and assumptions on the distribution of externally defined doses.
Cro S, Cornelius V, Capon F, et al., 2022, The interleukin 1 receptor antagonist anakinra to reduce disease severity of palmoplantar pustulosis in adults: APRICOT RCT and PLUM mechanistic study, Efficacy and Mechanism Evaluation, Vol: 9, Pages: 1-106, ISSN: 2050-4365
BackgroundPalmoplantar pustulosis is a rare, debilitating, chronic skin disease involving the hands and feet, and there are limited treatment options. Mechanistic findings suggest that interleukin 1 may be a pathogenic driver.ObjectiveTo determine whether or not anakinra [Sobi (Swedish Orphan Biovitrum AB), Stockholm, Sweden], an interleukin 1 receptor antagonist, delivers therapeutic benefit in palmoplantar pustulosis.DesignA Phase IV, randomised, double-blind, placebo-controlled study with two stages and an adaptive element (24 participants in stage 1, 64 participants in total) with an open-label extension.SettingSixteen hospitals across England, Scotland and Wales.ParticipantsAdults (aged ≥ 18 years) with a diagnosis of palmoplantar pustulosis and a disease duration of > 6 months and of sufficient impact and severity to require systemic therapy.InterventionsParticipants were randomised (1 : 1) to daily self-administered subcutaneous injection of either anakinra or a placebo for 8 weeks.Main outcome measuresThe primary outcome was the Palmoplantar Pustulosis Area and Severity Index score measured at 0, 1, 4, 8 and 12 weeks, with the primary end point at 8 weeks adjusted for baseline. Secondary outcomes included other investigator-assessed efficacy measures of disease severity, safety measures and participant-reported measures of efficacy and impact.ResultsA total of 64 participants (mean baseline Palmoplantar Pustulosis Area and Severity Index score of 17.8, standard deviation 10.5) received anakinra (n = 31) or the placebo (n = 33). In the primary intention-to-treat analysis, which estimated the effect of the treatment policy, the mean treatment group difference at 8 weeks after adjustment for baseline Palmoplantar Pustulosis Area and Severity Index score was –1.65 (95% confidence interval –4.77 to 1.47; p = 0.300), in favour of anakinra relative to placebo, but was not statis
Cro S, Cornelius VR, Pink AE, et al., 2022, Anakinra for palmoplantar pustulosis: results from a randomized, double-blind, multicentre, two staged, adaptive placebo controlled trial (APRICOT)., British Journal of Dermatology, Vol: 186, Pages: 245-256, ISSN: 0007-0963
BACKGROUND: Palmoplantar pustulosis (PPP) is a rare, debilitating, chronic inflammatory skin disease affecting the hands and feet. Clinical, immunological and genetic findings suggest a pathogenic role for interleukin (IL)-1. OBJECTIVE: To determine whether anakinra (an IL-1 receptor antagonist) delivers therapeutic benefit for PPP. METHODS: A randomised (1:1), double-blind, two-staged, adaptive, UK multi-centre, placebo-controlled trial. Participants had a diagnosis of PPP (>6 months) requiring systemic therapy. Treatment was eight weeks of anakinra or placebo via daily self-administered subcutaneous injections. The primary outcome was the Palmoplantar Pustulosis Psoriasis Area and Severity Index (PPPASI) at 8 weeks. RESULTS: A total of 374 patients were screened and 64 were enrolled (31 anakinra, 33 placebo) with mean baseline PPPASI 17.8 (SD=10.5); PPP investigator's global assessment severe (50%) or moderate (50%). The baseline adjusted mean difference in PPPASI favoured anakinra but did not demonstrate superiority in intention-to-treat analysis, -1.65, 95% CI [-4.77 to 1.47], p=0.300. Secondary objective measures including fresh pustule count (2.94, 95% CI [-26.44 to 32.33] favouring anakinra), total pustule count (-30.08, 95% CI [-83.20 to 23.05] favouring placebo), and patient-reported outcomes, similarly did not show superiority of anakinra. When modelling the impact of adherence, the PPPASI complier average causal effect (CACE) for an individual who receives ≥90% total treatment (48% anakinra group), was -3.80, 95% CI [-10.76 to 3.16], p=0.285. No serious adverse events occurred. CONCLUSIONS: No evidence for superiority of anakinra was found. IL-1 blockade is not a useful intervention for the treatment of PPP.
Van Vogt E, Cro S, Cornelius VR, et al., 2021, Individual participant data meta-analysis versus aggregate data meta-analysis: a case study in eczema and food allergy prevention., Clinical and Experimental Allergy, Vol: 52, ISSN: 0954-7894
INTRODUCTION: Meta-analysis traditionally uses aggregate data from published reports. Individual Participant Data (IPD) meta-analysis, which obtains and synthesises participant-level data, is potentially more informative, but resource-intensive. The impact on the findings of meta-analyses using IPD in comparison to aggregate data has rarely been formally evaluated. METHODS: We conducted a secondary analysis of a Cochrane systematic review of skin care interventions for preventing eczema and food allergy in infants to identify the impact of the analytical choice on the review's findings. We used aggregate data meta-analysis only and contrasted the results against those of the originally published IPD meta-analysis. All meta-analysis used random effects inverse variance models. Certainty of evidence was evaluated using GRADE. RESULTS: The pooled treatment effects for the Cochrane systematic review's co-primary outcomes of eczema and food allergy were similar in IPD meta-analysis (eczema RR 1.03, 95% CI 0.81, 1.31; I2 41%, 7 studies 3075 participants), and aggregate meta-analysis (eczema RR 1.01 95% CI 0.77, 1.33; I2 53%, 7 studies, 3089 participants). In aggregate meta-analysis the statistical heterogeneity could not be explained but using IPD it was explained by one trial which used a different, bathing intervention. For IPD meta-analysis, risk of bias was assessed as lower and more adverse event data were available compared with aggregate meta-analysis. This resulted in higher certainty of evidence, especially for adverse events. IPD meta-analysis enabled analysis of treatment interactions by age and hereditary eczema risk; and analysis of the effect of treatment adherence using pooled complier-adjusted-causal-effect analysis, none of which was possible in aggregate meta-analysis. CONCLUSIONS: For this systematic review, IPD did not significantly change primary outcome risk ratios compared with aggregate data meta-analysis. However, certainty of evidence, safety out
Partington G, Cro S, Mason A, et al., 2021, Design and analysis features used in small population and rare disease trials: A targeted review., Journal of Clinical Epidemiology, Vol: 144, Pages: 93-101, ISSN: 0895-4356
OBJECTIVE: Frequentist trials in Rare disease/small population trials often require unfeasibly large sample size to detect minimum clinically important differences. A targeted review was performed investigating what design and analysis methods these trials use when facing restricted recruitment. STUDY DESIGN AND SETTING: Targeted Review searching EMBASE and MEDLINE for Phase II-IV RCTs reporting 'rare' disease or 'small population' within title or abstract, since 2009. RESULTS: A total of 6,128 articles were screened with 64 trials eligible (4 Bayesian, 60 frequentist trials). Frequentists trials had planned power ranging 72-90% (median: 80%) but reported recruiting a mean of 6.6% below the planned sample size (n=38) [median 0%, IQR (-5%, 5%)], most used standard type 1 error (52 used 5% and 1 used 1%), and the average standardised effect was high (0.7) with 50% missing their assumed level. Of the 4 Bayesian trials, 3 used informed priors, 2 and 1 trials performed sensitivity analysis for the impact of priors on design and analysis respectively. Historical data, expert consensus, or both were used to construct informative priors. Bayesian trials required 30%-2400% less participants than using frequentist frameworks. CONCLUSION: Bayesian trials required lower sample size through use of informative priors. Most frequentists didn't achieve their target sample size. Bayesian methods offer promising solutions for such trials but are underutilised.
Kahan B, Morris TP, White IR, et al., 2021, Estimands in published protocols of randomised trials: urgent improvement needed, Trials, Vol: 22, ISSN: 1745-6215
Background:An estimand is a precise description of the treatment effect to be estimated from a trial (the question) and is distinct from the methods of statistical analysis (how the question is to be answered). The potential use of estimands to improve trial research and reporting has been underpinned by the recent publication of the ICH E9(R1) Addendum on the use of estimands in clinical trials in 2019. We set out to assess how well estimands are described in published trial protocols.Methods:We reviewed 50 trial protocols published in October 2020 in Trials and BMJ Open. For each protocol, we determined whether the estimand for the primary outcome was explicitly stated, not stated but inferable (i.e. could be constructed from the information given), or not inferable.Results:None of the 50 trials explicitly described the estimand for the primary outcome, and in 74% of trials, it was impossible to infer the estimand from the information included in the protocol. The population attribute of the estimand could not be inferred in 36% of trials, the treatment condition attribute in 20%, the population-level summary measure in 34%, and the handling of intercurrent events in 60% (the strategy for handling non-adherence was not inferable in 32% of protocols, and the strategy for handling mortality was not inferable in 80% of the protocols for which it was applicable). Conversely, the outcome attribute was stated for all trials. In 28% of trials, three or more of the five estimand attributes could not be inferred.Conclusions:The description of estimands in published trial protocols is poor, and in most trials, it is impossible to understand exactly what treatment effect is being estimated. Given the utility of estimands to improve clinical research and reporting, this urgently needs to change.
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