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1.
Informative cluster size in cluster-randomised trials: A case study from the TRIGGER trial
Kahan, B. C., Li, F., Blette, B., Jairath, V., Copas, A., Harhay, M.
Clinical trials (London, England). 2023;:17407745231186094
Abstract
BACKGROUND Recent work has shown that cluster-randomised trials can estimate two distinct estimands: the participant-average and cluster-average treatment effects. These can differ when participant outcomes or the treatment effect depends on the cluster size (termed informative cluster size). In this case, estimators that target one estimand (such as the analysis of unweighted cluster-level summaries, which targets the cluster-average effect) may be biased for the other. Furthermore, commonly used estimators such as mixed-effects models or generalised estimating equations with an exchangeable correlation structure can be biased for both estimands. However, there has been little empirical research into whether informative cluster size is likely to occur in practice. METHOD We re-analysed a cluster-randomised trial comparing two different thresholds for red blood cell transfusion in patients with acute upper gastrointestinal bleeding to explore whether estimates for the participant- and cluster-average effects differed, to provide empirical evidence for whether informative cluster size may be present. For each outcome, we first estimated a participant-average effect using independence estimating equations, which are unbiased under informative cluster size. We then compared this to two further methods: (1) a cluster-average effect estimated using either weighted independence estimating equations or unweighted cluster-level summaries, and (2) estimates from a mixed-effects model or generalised estimating equations with an exchangeable correlation structure. We then performed a small simulation study to evaluate whether observed differences between cluster- and participant-average estimates were likely to occur even if no informative cluster size was present. RESULTS For most outcomes, treatment effect estimates from different methods were similar. However, differences of >10% occurred between participant- and cluster-average estimates for 5 of 17 outcomes (29%). We also observed several notable differences between estimates from mixed-effects models or generalised estimating equations with an exchangeable correlation structure and those based on independence estimating equations. For example, for the EQ-5D VAS score, the independence estimating equation estimate of the participant-average difference was 4.15 (95% confidence interval: -3.37 to 11.66), compared with 2.84 (95% confidence interval: -7.37 to 13.04) for the cluster-average independence estimating equation estimate, and 3.23 (95% confidence interval: -6.70 to 13.16) from a mixed-effects model. Similarly, for thromboembolic/ischaemic events, the independence estimating equation estimate for the participant-average odds ratio was 0.43 (95% confidence interval: 0.07 to 2.48), compared with 0.33 (95% confidence interval: 0.06 to 1.77) from the cluster-average estimator. CONCLUSION In this re-analysis, we found that estimates from the various approaches could differ, which may be due to the presence of informative cluster size. Careful consideration of the estimand and the plausibility of assumptions underpinning each estimator can help ensure an appropriate analysis methods are used. Independence estimating equations and the analysis of cluster-level summaries (with appropriate weighting for each to correspond to either the participant-average or cluster-average treatment effect) are a desirable choice when informative cluster size is deemed possible, due to their unbiasedness in this setting.
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2.
Effects of Autologous Platelet-Rich Plasma on Healing of Peptic Ulcers: A Randomized Controlled Trial
Xu T, Tian Y, Wang Y, Yi Z, Li C, Wang S, Fan Y, Yao C, Peng G, Lu H
Gastroenterology research and practice. 2022;2022:7944849
Abstract
PURPOSE Peptic ulcer is a multifactorial and complex disease and affects a wide range of people worldwide. We provided a novel therapeutic approach for peptic ulcer and observed its effect. METHODS Peptic ulcer patients were enrolled from 2016 to 2017 in Chongqing and randomly assigned to two groups: a control group that used only rabeprazole and a platelet-rich plasma (PRP) group that received a combination therapy of autologous PRP (aPRP) and rabeprazole. The therapeutic effect was assessed via the ulcer size and symptom score. RESULTS A total of 27 patients were included (12 patients in the control group and 15 patients in the PRP group) in this study. Our results showed that all participants have healed in 30 days, and there was no significant difference in healing time between the PRP group and the control group in different independent variables. However, regression analysis revealed that the healing time was 6.99 days shorter in the PRP group than that in the control group, and patients with higher symptom scores in the initial examination need more time to heal during treatment. Endoscopic results showed that the repaired ulcer in the PRP group was more similar to the normal gastric mucosa tissue than that the control group. CONCLUSION This study showed an encouraging preliminary result that aPRP has a positive result in patients with peptic ulcer and seems to be a better choice for refractory peptic ulcer treatment. Although further follow-up studies are needed to determine the duration of efficacy of aPRP, the approach will be helpful in improving the clinical treatment of peptic ulcer.
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3.
Endoscopic treatment for high-risk bleeding peptic ulcers: a randomized, controlled trial of epinephrine alone with epinephrine plus fresh frozen plasma
Khodadoostan M, Karami-Horestani M, Shavakhi A, Sebghatollahi V
Journal of Research in Medical Sciences.. 2016;21:135.
Abstract
BACKGROUND Acute upper gastrointestinal bleeding is a common and potentially life-threatening emergency with substantial mortality. Fresh frozen plasma (FFP), a good source of coagulation factors, might be an ideal injection agent based on its physiologic properties. Therefore, we evaluated the role of FFP as a hemostatic agent in patients with high-risk bleeding peptic ulcers. MATERIALS AND METHODS From August 2015 to April 2016, 108 consecutive patients with high-risk bleeding ulcers were admitted to our university hospital. They were randomly assigned to undergo injection of epinephrine alone (A) or epinephrine plus FFP (B). The primary outcomes assessed were the initial hemostasis, recurrent bleeding, hospital stay, blood transfusion, surgery rate, and 14-day mortality. RESULTS Initial hemostasis was achieved in 47 of 50 patients (94%) in the Group A and 49 of 50 patients (98%) in the Group B (P = 0.61). There were no significant differences in the rate of recurrent bleeding between Group A (14%) and Group B (8%) (P = 0.52). We found no significant differences between Group A and Group B with respect to the surgery rate, bleeding death, procedure-related death, and duration of hospitalization (P > 0.05). CONCLUSION It is concluded the injection of epinephrine alone was equally effective as injection of epinephrine plus FFP to endoscopic hemostasis. Epinephrine alone and epinephrine plus FFP were not different in recurrent bleeding, rate of surgery, blood transfusion, or mortality.
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4.
Restrictive versus liberal blood transfusion for acute upper gastrointestinal bleeding (TRIGGER): a pragmatic, open-label, cluster randomised feasibility trial
Jairath V, Kahan BC, Gray A, Dore CJ, Mora A, James MW, Stanley AJ, Everett SM, Bailey AA, Dallal H, et al
Lancet. 2015;386((9989)):137-44.
Abstract
BACKGROUND Transfusion thresholds for acute upper gastrointestinal bleeding are controversial. So far, only three small, underpowered studies and one single-centre trial have been done. Findings from the single-centre trial showed reduced mortality with restrictive red blood cell (RBC) transfusion. We aimed to assess whether a multicentre, cluster randomised trial is a feasible method to substantiate or refute this finding. METHODS In this pragmatic, open-label, cluster randomised feasibility trial, done in six university hospitals in the UK, we enrolled all patients aged 18 years or older with new presentations of acute upper gastrointestinal bleeding, irrespective of comorbidity, except for exsanguinating haemorrhage. We randomly assigned hospitals (1:1) with a computer-generated randomisation sequence (random permuted block size of 6, without stratification or matching) to either a restrictive (transfusion when haemoglobin concentration fell below 80 g/L) or liberal (transfusion when haemoglobin concentration fell below 100 g/L) RBC transfusion policy. Neither patients nor investigators were masked to treatment allocation. Feasibility outcomes were recruitment rate, protocol adherence, haemoglobin concentration, RBC exposure, selection bias, and information to guide design and economic evaluation of the phase 3 trial. Main exploratory clinical outcomes were further bleeding and mortality at day 28. We did analyses on all enrolled patients for whom an outcome was available. This trial is registered, ISRCTN85757829 and NCT02105532. FINDINGS Between Sept 3, 2012, and March 1, 2013, we enrolled 936 patients across six hospitals (403 patients in three hospitals with a restrictive policy and 533 patients in three hospitals with a liberal policy). Recruitment rate was significantly higher for the liberal than for the restrictive policy (62% vs 55%; p=004). Despite some baseline imbalances, Rockall and Blatchford risk scores were identical between policies. Protocol adherence was 96% (SD 10) in the restrictive policy vs 83% (25) in the liberal policy (difference 14%; 95% CI 7-21; p=0005). Mean last recorded haemoglobin concentration was 116 (SD 24) g/L for patients on the restrictive policy and 118 (20) g/L for those on the liberal policy (difference -20 [95% CI -120 to 70]; p=050). Fewer patients received RBCs on the restrictive policy than on the liberal policy (restrictive policy 133 [33%] vs liberal policy 247 [46%]; difference -12% [95% CI -35 to 11]; p=023), with fewer RBC units transfused (mean 12 [SD 21] vs 19 [28]; difference -07 [-16 to 03]; p=012), although these differences were not significant. We noted no significant difference in clinical outcomes. INTERPRETATION A cluster randomised design led to rapid recruitment, high protocol adherence, separation in degree of anaemia between groups, and non-significant reduction in RBC transfusion in the restrictive policy. A large cluster randomised trial to assess the effectiveness of transfusion strategies for acute upper gastrointestinal bleeding is both feasible and essential before clinical practice guidelines change to recommend restrictive transfusion for all patients with acute upper gastrointestinal bleeding. FUNDING NHS Blood and Transplant Research and Development.Copyright © 2015 Elsevier Ltd. All rights reserved.
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5.
Restrictive versus liberal blood transfusion for acute upper gastrointestinal bleeding (trigger): pragmatic, cluster randomised, feasibility trial
Gray A, Jairath V, Kahan B, Dore C, Palmer K, Travis S, Logan R, Walsh T, Murphy M
Emergency Medicine Journal. 2014;31((9):):780.. Abstract No. 008
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6.
Update on the transfusion in gastrointestinal bleeding (TRIGGER) trial: statistical analysis plan for a cluster-randomised feasibility trial
Kahan BC, Jairath V, Murphy MF, Dore CJ
Trials [Electronic Resource]. 2013;14:206
Abstract
BACKGROUND Previous research has suggested an association between more liberal red blood cell (RBC) transfusion and greater risk of further bleeding and mortality following acute upper gastrointestinal bleeding (AUGIB). METHODS AND DESIGN The Transfusion in Gastrointestinal Bleeding (TRIGGER) trial is a pragmatic cluster-randomised feasibility trial which aims to evaluate the feasibility of implementing a restrictive vs. liberal RBC transfusion policy for adult patients admitted to hospital with AUGIB in the UK. This trial will help to inform the design and methodology of a phase III trial. The protocol for TRIGGER has been published in Transfusion Medicine Reviews. Recruitment began in September 2012 and was completed in March 2013. This update presents the statistical analysis plan, detailing how analysis of the TRIGGER trial will be performed. It is hoped that prospective publication of the full statistical analysis plan will increase transparency and give readers a clear overview of how TRIGGER will be analysed. TRIAL REGISTRATION ISRCTN85757829.
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7.
Transfusion strategies for acute upper gastrointestinal bleeding
Villanueva C, Colomo A, Bosch A, Concepcion M, Hernandez-Gea V, Aracil C, Graupera I, Poca M, Alvarez-Urturi C, Gordillo J, et al
New England Journal of Medicine. 2013;368((1):):11-21.
Abstract
BACKGROUND The hemoglobin threshold for transfusion of red cells in patients with acute gastrointestinal bleeding is controversial. We compared the efficacy and safety of a restrictive transfusion strategy with those of a liberal transfusion strategy. METHODS We enrolled 921 patients with severe acute upper gastrointestinal bleeding and randomly assigned 461 of them to a restrictive strategy (transfusion when the hemoglobin level fell below 7 g per deciliter) and 460 to a liberal strategy (transfusion when the hemoglobin fell below 9 g per deciliter). Randomization was stratified according to the presence or absence of liver cirrhosis. RESULTS A total of 225 patients assigned to the restrictive strategy (51%), as compared with 65 assigned to the liberal strategy (15%), did not receive transfusions (P<0.001). The probability of survival at 6 weeks was higher in the restrictive-strategy group than in the liberal-strategy group (95% vs. 91%; hazard ratio for death with restrictive strategy, 0.55; 95% confidence interval [CI], 0.33 to 0.92; P=0.02). Further bleeding occurred in 10% of the patients in the restrictive-strategy group as compared with 16% of the patients in the liberal-strategy group (P=0.01), and adverse events occurred in 40% as compared with 48% (P=0.02). The probability of survival was slightly higher with the restrictive strategy than with the liberal strategy in the subgroup of patients who had bleeding associated with a peptic ulcer (hazard ratio, 0.70; 95% CI, 0.26 to 1.25) and was significantly higher in the subgroup of patients with cirrhosis and Child-Pugh class A or B disease (hazard ratio, 0.30; 95% CI, 0.11 to 0.85), but not in those with cirrhosis and Child-Pugh class C disease (hazard ratio, 1.04; 95% CI, 0.45 to 2.37). Within the first 5 days, the portal-pressure gradient increased significantly in patients assigned to the liberal strategy (P=0.03) but not in those assigned to the restrictive strategy. CONCLUSIONS As compared with a liberal transfusion strategy, a restrictive strategy significantly improved outcomes in patients with acute upper gastrointestinal bleeding. (Funded by Fundacio Investigacio Sant Pau; ClinicalTrials.gov number, NCT00414713.).
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8.
Restrictive vs liberal blood transfusion for acute upper gastrointestinal bleeding: rationale and protocol for a cluster randomized feasibility trial
Jairath V, Kahan BC, Gray A, Dore CJ, Mora A, Dyer C, Stokes EA, Llewelyn C, Bailey AA, Dallal H, et al
Transfusion Medicine Reviews. 2013;27((3):):146-53.
Abstract
Acute upper gastrointestinal bleeding (AUGIB) is the commonest reason for hospitalization with hemorrhage in the UK and the leading indication for transfusion of red blood cells (RBCs). Observational studies suggest an association between more liberal RBC transfusion and adverse patient outcomes, and a recent randomised trial reported increased further bleeding and mortality with a liberal transfusion policy. TRIGGER (Transfusion in Gastrointestinal Bleeding) is a pragmatic, cluster randomized trial which aims to evaluate the feasibility and safety of implementing a restrictive versus liberal RBC transfusion policy in adult patients admitted with AUGIB. The trial will take place in 6 UK hospitals, and each centre will be randomly allocated to a transfusion policy. Clinicians throughout each hospital will manage all eligible patients according to the transfusion policy for the 6-month trial recruitment period. In the restrictive centers, patients become eligible for RBC transfusion when their hemoglobin is <8 g/dL. In the liberal centers patients become eligible for transfusion once their hemoglobin is <10 g/dL. All clinicians will have the discretion to transfuse outside of the policy but will be asked to document the reasons for doing so. Feasibility outcome measures include protocol adherence, recruitment rate, and evidence of selection bias. Clinical outcome measures include further bleeding, mortality, thromboembolic events, and infections. Quality of life will be measured using the EuroQol EQ-5D at day 28, and the costs associated with hospitalization for AUGIB in the UK will be estimated. Consent will be sought from participants or their representatives according to patient capacity for use of routine hospital data and day 28 follow up. The study has ethical approval for conduct in England and Scotland. Results will be analysed according to a pre-defined statistical analysis plan and disseminated in peer reviewed publications to relevant stakeholders. The results of this study will inform the feasibility and design of a phase III randomized trial. Copyright 2013 Elsevier Inc. All rights reserved.
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9.
Effectiveness of fresh frozen plasma as supplementary treatment in organophosphate poisoning
Pazooki S, Solhi H, Vishteh HR, Shadnia S, Beigi MJ
The Medical Journal of Malaysia. 2011;66((4):):342-5.
Abstract
With the establishment of the inadequate efficiency of atropines and oximes in reducing morbidity and mortality of patients poisoned by organophosphates, more attention is given to using other methods such as Fresh Frozen Plasma (FFP) as a bioscavenger to mop up organophosphate toxins. This randomized clinical trial was conducted on 56 organophosphate poisoned patients who were randomly assigned to the FFP and control groups in order of admission. The routine treatment in both groups included atropine and, in moderate to severe cases of poisoning, pralidoxime. The FFP group received four packs of FFP as stat dose at the beginning of treatment. No significant difference was seen between the two groups on the atropine and pralidoxime dosage, hospitalization length and mortality. The present study showed that using four packs of FFP as stat dose at the onset of treatment had no significant effect on the clinical course of organophosphate poisoned patients.
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10.
The effects of fresh frozen plasma on cholinesterase levels and outcomes in patients with organophosphate poisoning
Güven M, Sungur M, Eser B, Sari I, Altunta F
Clinical Toxicology. 2004;42((5):):617-23.
Abstract
OBJECTIVE The aim of this study is to determine the effects of fresh frozen plasma, as a source of cholinesterase, on butyrylcholinesterase (BuChE; plasma or pseudo cholinesterase) levels and outcomes in patients with organophosphate poisoning. MATERIALS AND METHODS This prospective study was performed at the Department of Intensive Care of Erciyes University Medical School. Over 2 yrs, patients admitted to the ICU for OP poisoning were entered into the study. OP poisoning was diagnosed on the basis of history and BuChE levels. All patients received atropine. Fresh frozen plasma was given to 12 patients. The study was approved by the Ethical Committee, and verbal informed consent was obtained. RESULTS Thirty-three patients were included in the study. BuChE levels measured at admission and the pralidoxime and atropine doses administered were not different between groups (p>0. 05). Although intermediate syndrome developed in 28. 6% of patients receiving pralidoxime, there were no intermediate syndrome cases in patients receiving plasma prior to developing intermediate syndrome. The mortality rates were 14. 3% in the pralidoxime group and 0% in the plasma+atropine+pralidoxime group. Two patients received plasma after developing the intermediate syndrome, and one patient who received only atropine died. BuChE levels of fresh frozen plasma were 4069. 5 +/- 565. 1 IU/L. Every two bags of plasma provided an increase in BuChE levels of approximately 461. 7 +/- 142. 1 IU/L. CONCLUSION Fresh frozen plasma therapy increases BuChE levels in patients with organophosphate poisonings. The administration of plasma may also prevent the development of intermediate syndrome and related mortality. Plasma (fresh frozen or freshly prepared) therapy may be used as an alternative or adjunctive treatment method in patients with organophosphate pesticide poisoning, especially in cases not given pralidoxime. Further randomized controlled and animal studies are required to infer a definitive result.