Effects of IV fluid restriction according to site-specific intensity of standard fluid treatment-protocol.

BACKGROUND: Variation in usual practice in fluid trials assessing lower versus higher volumes may affect overall comparisons. To address this, we will evaluate the effects of heterogeneity in treatment intensity in the Conservative versus Liberal Approach to Fluid Therapy of Septic Shock in Intensive Care trial. This will reflect the effects of differences in site-specific intensities of standard fluid treatment due to local practice preferences while considering participant characteristics. METHODS: We will assess the effects of heterogeneity in treatment intensity across one primary (all-cause mortality) and three secondary outcomes (serious adverse events or reactions, days alive without life support and days alive out of hospital) after 90 days. We will classify sites based on the site-specific intensity of standard fluid treatment, defined as the mean differences in observed versus predicted intravenous fluid volumes in the first 24 h in the standard-fluid group while accounting for differences in participant characteristics. Predictions will be made using a machine learning model including 22 baseline predictors using the extreme gradient boosting algorithm. Subsequently, sites will be grouped into fluid treatment intensity subgroups containing at least 100 participants each. Subgroups differences will be assessed using hierarchical Bayesian regression models with weakly informative priors. We will present the full posterior distributions of relative (risk ratios and ratios of means) and absolute differences (risk differences and mean differences) in each subgroup. DISCUSSION: This study will provide data on the effects of heterogeneity in treatment intensity while accounting for patient characteristics in critically ill adult patients with septic shock. REGISTRATIONS: The European Clinical Trials Database (EudraCT): 2018-000404-42, ClinicalTrials. gov: NCT03668236.

Effects of restrictive fluid therapy on the time to resolution of hyperlactatemia in ICU patients with septic shock. A secondary post hoc analysis of the CLASSIC randomized trial.

PURPOSE: The aim of this study was to examine the effects of intravenous (IV) fluid restriction on time to resolution of hyperlactatemia in septic shock. Hyperlactatemia in sepsis is associated with worse outcome. Sepsis guidelines suggest targeting lactate clearance to guide fluid therapy despite the complexity of hyperlactatemia and the potential harm of fluid overload. METHODS: We conducted a post hoc analysis of serial plasma lactate concentrations in a sub-cohort of 777 patients from the international multicenter clinical CLASSIC trial (restriction of intravenous fluids in intensive care unit (ICU) patients with septic shock). Adult ICU patients with septic shock had been randomized to restrictive (n = 385) or standard (n = 392) intravenous fluid therapy. The primary outcome, time to resolution of hyperlactatemia, was analyzed with a competing-risks regression model. Death and discharge were competing outcomes, and administrative censoring was imposed 72 h after randomization if hyperlactatemia persisted. The regression analysis was adjusted for the same stratification variables and covariates as in the original CLASSIC trial analysis. RESULTS: The hazard ratios (HRs) for the cumulative probability of resolution of hyperlactatemia, in the restrictive vs the standard group, in the unadjusted analysis, with time split, were 0.94 (confidence interval (CI) 0.78-1.14) at day 1 and 1.21 (0.89-1.65) at day 2-3. The adjusted analyses were consistent with the unadjusted results. CONCLUSION: In this post hoc retrospective analysis of a multicenter randomized controlled trial (RCT), a restrictive intravenous fluid strategy did not seem to affect the time to resolution of hyperlactatemia in adult ICU patients with septic shock.

Real-world causal evidence for planned predictive enrichment in critical care trials: A scoping review.

BACKGROUND: Randomised clinical trials in critical care are prone to inconclusiveness due, in part, to undue optimism about effect sizes and suboptimal accounting for heterogeneous treatment effects. Although causal evidence from rich real-world critical care can help overcome these challenges by informing predictive enrichment, no overview exists. METHODS: We conducted a scoping review, systematically searching 10 general and speciality journals for reports published on or after 1 January 2018, of randomised clinical trials enrolling adult critically ill patients. We collected trial metadata on 22 variables including recruitment period, intervention type and early stopping (including reasons) as well as data on the use of causal evidence from secondary data for planned predictive enrichment. RESULTS: We screened 9020 records and included 316 unique RCTs with a total of 268,563 randomised participants. One hundred seventy-three (55%) trials tested drug interventions, 101 (32%) management strategies and 42 (13%) devices. The median duration of enrolment was 2.2 (IQR: 1.3-3.4) years, and 83% of trials randomised less than 1000 participants. Thirty-six trials (11%) were restricted to COVID-19 patients. Of the 55 (17%) trials that stopped early, 23 (42%) used predefined rules; futility, slow enrolment and safety concerns were the commonest stopping reasons. None of the included RCTs had used causal evidence from secondary data for planned predictive enrichment. CONCLUSION: Work is needed to harness the rich multiverse of critical care data and establish its utility in critical care RCTs. Such work will likely need to leverage methodology from interventional and analytical epidemiology as well as data science.

Albumin use in patients with septic shock-Post-hoc analyses of an international randomised fluid trial.

BACKGROUND: Albumin administration is suggested in patients with sepsis and septic shock who have received large volumes of crystalloids. Given lack of firm evidence, clinical practice variation may exist. To address this, we investigated if patient characteristics or trial site were associated with albumin use in septic shock. METHODS: We conducted a post-hoc study of the CLASSIC international, randomised clinical trial of fluid volumes in septic shock. Associations between selected baseline variables and trial site with albumin use during ICU stay were assessed in Cox models considering death, ICU discharge, and loss-to-follow-up as competing events. Baseline variables were first assessed individually, adjusted for treatment allocation (restrictive vs. standard IV fluid), and then adjusted for allocation and the other baseline variables. Site was assessed in a model adjusted for allocation and baseline variables. RESULTS: We analysed 1541 of 1554 patients randomised in CLASSIC (99.2%). During ICU stay, 36.3% of patients in the restrictive-fluid group and 52.6% in the standard-fluid group received albumin. Gastrointestinal focus of infection and higher doses of norepinephrine were most strongly associated with albumin use (subgroup with highest quartile of norepinephrine doses, hazard ratio (HR) 2.58, 95% CI 1.89 to 3.53). HRs for associations between site and albumin use ranged from 0.11 (95% CI 0.05 to 0.26) to 1.70 (95% CI 1.06 to 2.74); test for overall effect of site: p < .001. CONCLUSIONS: In adults with septic shock, gastrointestinal focus of infection and higher doses of norepinephrine at baseline were associated with albumin use, which also varied substantially between sites.

Restrictive versus standard IV fluid therapy in adult ICU patients with septic shock-Bayesian analyses of the CLASSIC trial.

BACKGROUND: The CLASSIC trial assessed the effects of restrictive versus standard intravenous (IV) fluid therapy in adult intensive care unit (ICU) patients with septic shock. This pre-planned study provides a probabilistic interpretation and evaluates heterogeneity in treatment effects (HTE). METHODS: We analysed mortality, serious adverse events (SAEs), serious adverse reactions (SARs) and days alive without life-support within 90 days using Bayesian models with weakly informative priors. HTE on mortality was assessed according to five baseline variables: disease severity, vasopressor dose, lactate levels, creatinine values and IV fluid volumes given before randomisation. RESULTS: The absolute difference in mortality was 0.2%-points (95% credible interval: -5.0 to 5.4; 47% posterior probability of benefit [risk difference <0.0%-points]) with restrictive IV fluid. The posterior probabilities of benefits with restrictive IV fluid were 72% for SAEs, 52% for SARs and 61% for days alive without life-support. The posterior probabilities of no clinically important differences (absolute risk difference ≤2%-points) between the groups were 56% for mortality, 49% for SAEs, 90% for SARs and 38% for days alive without life-support. There was 97% probability of HTE for previous IV fluid volumes analysed continuously, that is, potentially relatively lower mortality of restrictive IV fluids with higher previous IV fluids. No substantial evidence of HTE was found in the other analyses. CONCLUSION: We could not rule out clinically important effects of restrictive IV fluid therapy on mortality, SAEs or days alive without life-support, but substantial effects on SARs were unlikely. IV fluids given before randomisation might interact with IV fluid strategy.

Long-term effects of restriction of intravenous fluid in adult ICU patients with septic shock.

PURPOSE: To assess long-term outcomes of restrictive versus standard intravenous (IV) fluid therapy in adult intensive care unit (ICU) patients with septic shock included in the European Conservative versus Liberal Approach to Fluid Therapy in Septic Shock in Intensive Care (CLASSIC) trial. METHODS: We conducted the pre-planned analyses of mortality, health-related quality of life (HRQoL) using EuroQol (EQ)-5D-5L index values and EQ visual analogue scale (VAS), and cognitive function using Mini Montreal Cognitive Assessment (Mini MoCA) test at 1 year. Deceased patients were assigned numerical zero for HRQoL as a state equal to death and zero for cognitive function outcomes as worst possible score, and we used multiple imputation for missing data on HRQoL and cognitive function. RESULTS: Among 1554 randomized patients, we obtained 1-year data on mortality in 97.9% of patients, HRQoL in 91.3%, and cognitive function in 86.3%. One-year mortality was 385/746 (51.3%) in the restrictive-fluid group versus 383/767 (49.9%) in the standard-fluid group, absolute risk difference 1.5%-points [99% confidence interval (CI) - 4.8 to 7.8]. Mean differences were 0.00 (99% CI - 0.06 to 0.05) for EQ-5D-5L index values, - 0.65 for EQ VAS (- 5.40 to 4.08), and - 0.14 for Mini MoCA (- 1.59 to 1.14) for the restrictive-fluid group versus the standard-fluid group. The results for survivors only were similar in both groups. CONCLUSIONS: Among adult ICU patients with septic shock, restrictive versus standard IV fluid therapy resulted in similar survival, HRQoL, and cognitive function at 1 year, but clinically important differences could not be ruled out.

Protocol for a systematic review and meta-analysis assessing conservative versus liberal intravenous fluid administration in patients with sepsis or septic shock at risk of fluid overload.

INTRODUCTION: Intravenous crystalloid fluid resuscitation forms a crucial part of the early intervention bundle for sepsis and septic shock, with the Surviving Sepsis Campaign guidelines recommending a 30 mL/kg fluid bolus within the first hour. Compliance with this suggested target varies in patients with comorbidities such as congestive heart failure, chronic kidney disease and cirrhosis due to concerns regarding iatrogenic fluid overload. However, it remains unclear whether resuscitation with higher fluid volumes puts them at greater risk of adverse outcomes. Thus, this systematic review will synthesise evidence from existing studies to assess the effects of a conservative as compared with a liberal approach to fluid resuscitation in patients at greater perceived risk of fluid overload due to comorbid conditions. METHODS AND ANALYSIS: This protocol was registered on PROSPERO and has been drafted following the checklist of Preferred Reporting Items for Systematic Review and Meta-Analysis Protocols. We will search MEDLINE, MEDLINE Epub Ahead of Print and In-Process, In-Data-Review & Other Non-Indexed Citations, Embase, Embase Classic, Cochrane Central Register of Controlled Trials, Cochrane Database of Systematic Reviews, Web of Science Core Collection, CINAHL Complete and ClinicalTrials.gov. A preliminary search of these databases was performed from their inception to 30 August 2022. The risk of bias and random errors will be assessed using the revised Cochrane risk-of-bias tool for randomised clinical trials and the Newcastle-Ottawa Scale for case-control and cohort studies. If a sufficient number of comparable studies are identified, we will perform a meta-analysis applying random effects model. We will investigate heterogeneity using a combination of visual inspection of the funnel plot as well as the Egger's test. ETHICS AND DISSEMINATION: No ethics approval is required for this study since no original data will be collected. The findings will be disseminated through peer-reviewed publication and conference presentation. PROSPERO REGISTRATION NUMBER: CRD42022348181.

Albumin administration in septic shock-Protocol for post-hoc analyses of data from a multicentre RCT.

BACKGROUND: Intravenous (IV) albumin is suggested for patients with septic shock who have received large amounts of IV crystalloids; a conditional recommendation based on moderate certainty of evidence. Clinical variation in the administration of IV albumin in septic shock may exist according to patient characteristics and location. METHODS: This is a protocol and statistical analysis plan for a post-hoc secondary study of the Conservative versus Liberal Approach to Fluid Therapy of Septic Shock in Intensive Care (CLASSIC) RCT of 1554 adult ICU patients with septic shock. We will assess if specific baseline characteristics or trial site are associated with the administration of IV albumin during ICU stay using Cox models with competing events. All models will be adjusted for the treatment allocation in CLASSIC (restrictive vs. standard IV fluid), and all analyses will consider competing events (death, ICU discharge and loss-to-follow-up). We will present results as hazard ratios with 95% confidence intervals and p-values for the associations of baseline characteristics or site with IV albumin administration. Between-group differences (interactions) will be assessed using p-values from likelihood ratio tests. All results will be considered exploratory only. DISCUSSION: This secondary study of the CLASSIC RCT may yield important insight into potential practice variation in the administration of albumin in septic shock.

Lower vs Higher Fluid Volumes in Adult Patients With Sepsis: An Updated Systematic Review With Meta-Analysis and Trial Sequential Analysis.

BACKGROUND: IV fluids are recommended for adults with sepsis. However, the optimal strategy for IV fluid management in sepsis is unknown, and clinical equipoise exists. RESEARCH QUESTION: Do lower vs higher fluid volumes improve patient-important outcomes in adult patients with sepsis? STUDY DESIGN AND METHODS: We updated a systematic review with meta-analysis and trial sequential analysis of randomized clinical trials assessing lower vs higher IV fluid volumes in adult patients with sepsis. The coprimary outcomes were all-cause mortality, serious adverse events, and health-related quality of life. We followed the recommendations from the Cochrane Handbook and used the Grading of Recommendations Assessment, Development and Evaluation approach. Primary conclusions were based on trials with low risk of bias if available. RESULTS: We included 13 trials (N = 4,006) with four trials (n = 3,385) added to this update. The meta-analysis of all-cause mortality in eight trials with low risk of bias showed a relative risk of 0.99 (97% CI, 0.89-1.10; moderate certainty evidence). Six trials with predefined definitions of serious adverse events showed a relative risk of 0.95 (97% CI, 0.83-1.07; low certainty evidence). Health-related quality of life was not reported. INTERPRETATION: Among adult patients with sepsis, lower IV fluid volumes probably result in little to no difference in all-cause mortality compared with higher IV fluid volumes, but the interpretation is limited by imprecision in the estimate, which does not exclude potential benefit or harm. Similarly, the evidence suggests lower IV fluid volumes result in little to no difference in serious adverse events. No trials reported on health-related quality of life. TRIAL REGISTRATION: PROSPERO; No.: CRD42022312572; URL: https://www.crd.york.ac.uk/prospero/.

Patient and public involvement in contemporary large intensive care trials: A meta-epidemiological study.

BACKGROUND: Patient and public involvement in randomised clinical trials has received increased focus, including in intensive care trials, but the frequency, method and extent is unknown. This meta-epidemiological study investigated patient and public involvement in contemporary, large ICU trials. METHODS: We systematically searched PubMed for large (≥225 randomised patients), contemporary trials (published between 1 January 2019 and 31 January 2022) assessing interventions in adult patients in ICU settings. Abstracts and full-text articles were assessed independently and in duplicate. Data were extracted using a pre-defined, pilot-tested data extraction form with details on trials, patient and public involvement including categories and numbers of individuals involved, methods of involvement, and trial stage(s) with involvement. Trials authors were contacted as necessary. RESULTS: We included 100 trials, with 18 using patient and public involvement; these were larger and conducted in more centres than trials without patient and public involvement. Among trials with patient and public involvement, patients (in 14/18 trials), clinicians (13 trials), and family members (12 trials) were primarily involved, mainly in the development of research design (15 trials) and development of research focus (13 trials) stages and mostly by discussion (12 trials) and solo interviews (10 trials). A median of 65 individuals (range 1-6894) were involved. CONCLUSIONS: We found patient and public involvement in a fifth of large, contemporary ICU trials. Primarily patients, families, and clinicians were included, particularly in the trial planning stages and mostly through interviews and discussions. Increased patient and public involvement in ICU trials is warranted.

Causal inference for planning randomised critical care trials: Protocol for a scoping review.

BACKGROUND: Randomised clinical trials in critical care are prone to inconclusiveness owing, in part, to undue optimism about effect sizes and suboptimal accounting for heterogeneous treatment effects. Planned predictive enrichment based on secondary critical care data (often very rich with respect to both data types and temporal granularity) and causal inference methods may help overcome these challenges, but no overview exists about their use to this end. METHODS: We will conduct a scoping review to assess the extent and nature of the use of causal inference from secondary data for planned predictive enrichment of randomised clinical trials in critical care. We will systematically search 10 general and specialty journals for reports published on or after 1 January 2018, of randomised clinical trials enrolling adult critically ill patients. We will collect trial metadata (e.g., recruitment period and phase) and, when available, information pertaining to the focus of the review (predictive enrichment based on causal inference estimates from secondary data): causal inference methods, estimation techniques and software used; types of patient populations; data provenance, types and models; and the availability of the data (public or not). The results will be reported in a descriptive manner. DISCUSSION: The outlined scoping review aims to assess the use of causal inference methods and secondary data for planned predictive enrichment in randomised critical care trials. This will help guide methodological improvements to increase the utility, and facilitate the use, of causal inference estimates when planning such trials in the future.

Patient-Important Outcomes Other Than Mortality in Contemporary ICU Trials: A Scoping Review.

OBJECTIVES: Randomized clinical trials (RCTs) conducted in adult ICU patients increasingly include patient-important outcomes other than mortality. This comes with challenges regarding outcome choices/definitions, handling of deceased patients and missing data in analyses, and choices of effect measures and statistical methods due to complex distributions. This scoping review aimed to characterize how these challenges are handled in relevant contemporary RCTs. DATA SOURCES: We systematically searched 10 selected journals for RCTs conducted primarily in adult ICU patients published between 1 January 2018 and 5 May 2022 reporting at least one patient-important outcome other than mortality, including "days alive without"…-type outcomes, functional/cognitive/neurologic outcomes, health-related quality of life (HRQoL) outcomes, and ordinal/other outcomes. STUDY SELECTION: Abstracts and full-texts were assessed independently and in duplicate by two reviewers. DATA EXTRACTION: Data were extracted independently and in duplicate by two reviewers using predefined and pilot-tested extraction forms and subsequently categorized to facilitate analysis. DATA SYNTHESIS: We included 687 outcomes from 167 RCTs, with 32% of RCTs using a patient-important outcome other than mortality as a (co-)primary outcome, most frequently "days alive without"…-type outcomes. Many different functional/cognitive/neurologic (103) and HRQoL (29) outcomes were reported. Handling of deceased patients varied, with analyses frequently restricted to survivors only for functional/cognitive/neurologic (62%) and HRQoL (89%) outcomes. Follow-up was generally longer and missing data proportions higher for functional/cognitive/neurologic and HRQoL outcomes. Most outcomes were analyzed using nonparametric tests (31%), linear regression/ t tests (27%), chi-square-like tests (12%), and proportional odds logistic regression (9%), often without presentation of actual treatment effects estimates (38%). CONCLUSIONS: In this sample of RCTs, substantial variation in practice and suboptimal methodological choices were observed. This calls for increased focus on standardizing outcome choices and definitions, adequate handling of missing data and deceased patients in analyses, and use of statistical methods quantifying effect sizes.

Restriction of Intravenous Fluid in ICU Patients with Septic Shock.

BACKGROUND: Intravenous fluids are recommended for the treatment of patients who are in septic shock, but higher fluid volumes have been associated with harm in patients who are in the intensive care unit (ICU). METHODS: In this international, randomized trial, we assigned patients with septic shock in the ICU who had received at least 1 liter of intravenous fluid to receive restricted intravenous fluid or standard intravenous fluid therapy; patients were included if the onset of shock had been within 12 hours before screening. The primary outcome was death from any cause within 90 days after randomization. RESULTS: We enrolled 1554 patients; 770 were assigned to the restrictive-fluid group and 784 to the standard-fluid group. Primary outcome data were available for 1545 patients (99.4%). In the ICU, the restrictive-fluid group received a median of 1798 ml of intravenous fluid (interquartile range, 500 to 4366); the standard-fluid group received a median of 3811 ml (interquartile range, 1861 to 6762). At 90 days, death had occurred in 323 of 764 patients (42.3%) in the restrictive-fluid group, as compared with 329 of 781 patients (42.1%) in the standard-fluid group (adjusted absolute difference, 0.1 percentage points; 95% confidence interval [CI], -4.7 to 4.9; P = 0.96). In the ICU, serious adverse events occurred at least once in 221 of 751 patients (29.4%) in the restrictive-fluid group and in 238 of 772 patients (30.8%) in the standard-fluid group (adjusted absolute difference, -1.7 percentage points; 99% CI, -7.7 to 4.3). At 90 days after randomization, the numbers of days alive without life support and days alive and out of the hospital were similar in the two groups. CONCLUSIONS: Among adult patients with septic shock in the ICU, intravenous fluid restriction did not result in fewer deaths at 90 days than standard intravenous fluid therapy. (Funded by the Novo Nordisk Foundation and others; CLASSIC ClinicalTrials.gov number, NCT03668236.).

Acetate- versus lactate-buffered crystalloid solutions: A systematic review with meta-analysis and trial sequential analysis.

OBJECTIVE: There is a widespread use of buffered crystalloid solutions in clinical practice. However, guidelines do not distinguish between specific types of buffered solutions and clinical equipoise exists. We aimed to assess the desirable and undesirable effects of acetate- versus lactate-buffered solutions in hospitalised patients. METHODS: We conducted a systematic review with meta-analysis and trial sequential analysis of randomised clinical trials assessing the use of acetate- versus lactate-buffered solutions for intravenous administration in hospitalised adults and children. The primary outcome was all-cause short-term mortality. We adhered to our published protocol, the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) statement, the Cochrane Handbook and the Grading of Recommendations, Assessment, Development and Evaluation (GRADE) methodology. RESULTS: We included five RCTs enrolling 390 patients. We found no statistically significant difference in short-term mortality (random effects, risk ratio [RR] 0.29; 95% confidence interval [CI] 0.06-1.51, p = .14, I2  = 0%) or hospital length of stay (LOS) (random effects, mean difference [MD]-1.31, 95% CI -3.66 to 1.05, p = .28, I2  = 0%) between acetate- versus lactate-buffered solutions. The quality of evidence was very low. Data regarding intensive care unit LOS were reported by three trials and duration of vasopressor treatment by one trial; none of these data allowed for pooling in meta-analyses. No trials reported data on long-term mortality, health-related quality of life, adverse events, duration of mechanical ventilation or renal replacement therapy. CONCLUSION: In this systematic review, we found very low quantity and quality of evidence on the use of acetate- versus lactate-buffered solutions in hospitalised patients.

Conservative vs. liberal fluid therapy in septic shock - Protocol for secondary Bayesian analyses of the CLASSIC trial.

BACKGROUND: Clinical equipoise exists regarding intravenous (IV) fluid volumes in sepsis. The Conservative vs. Liberal Approach to fluid therapy of Septic Shock in Intensive Care (CLASSIC) trial investigates the effect of restricted vs. standard IV fluid therapy in 1554 adult intensive care unit patients with septic shock. METHODS: This protocol describes secondary Bayesian analyses of the primary outcome (90-day all-cause mortality) and three secondary outcomes at day 90. We will analyse all binary outcomes with adjusted Bayesian logistic regressions and present results as conditional relative risks and risk differences with 95% credibility intervals (CrIs). The secondary count outcome will be analysed using adjusted Bayesian linear regression with results summarised as conditional mean differences and ratios of means with 95% Crls. We will use weakly informative priors for the primary analyses, and sceptical and evidence-based priors in the sensitivity analyses. Exact probabilities will be presented for any benefit/harm, clinically important benefit/harm and no clinically important difference. We will assess whether heterogeneity of treatment effects on mortality is present using Bayesian hierarchical models in subgroups and on the continuous scale using models with interactions according to five baseline variables assessing the overall severity of illness and the degree of circulatory and renal impairment. DISCUSSION: The outlined analyses will supplement the primary analysis of the CLASSIC trial by describing probabilities of beneficial and harmful effects and evaluating heterogeneity of treatment effects in a framework that may be easier to interpret for researchers and clinicians.

Development of a core outcome set for general intensive care unit patients-A protocol.

INTRODUCTION: Different outcomes are reported in randomised clinical trials (RCTs) in intensive care unit (ICU) patients, and no core outcome set (COS) is available for ICU patients in general. Accordingly, we aim to develop a COS for ICU patients in general. METHODS: The COS will be developed in accordance with the Core Outcome Measures in Effectiveness Trials (COMET) Handbook, using a modified Delphi consensus process and semi-structured interviews involving adults who have survived acute admission to an ICU, family members, clinicians, researchers and other stakeholders. The modified Delphi process will include two steps. Step 1: conduction of a modified Delphi survey, developed and informed by combining the outputs of a literature search of outcomes in previous COSs and semi-structured interviews with key stakeholders. We plan at least two survey rounds to obtain consensus and refine the COS. Step 2: a consensus process regarding instruments or definitions to be recommended for the measurements of the outcomes selected in Step 1. A 'patient and public involvement panel' consisting of a smaller group of patients, family members, clinicians and researchers will be included in the development, analysis and interpretation of the COS. DISCUSSION: The outlined multiple method studies will establish a COS for ICU patients in general, which may be used to increase the standardisation and comparability of results of RCTs conducted in patients in the ICU setting.

Patient and public involvement in contemporary large intensive care trials: Protocol for a meta-epidemiological study.

BACKGROUND: Patient and public involvement (PPI) in randomized clinical trials (RCTs) has increased in recent years but remains the exception rather than the rule. We aim to assess the frequency and extent of PPI in large, contemporary RCTs conducted in an intensive care setting. METHODS AND DESIGN: We will conduct a meta-epidemiological study of RCTs conducted in intensive care settings published since 2019 and assess their use of PPI. We will extract trial characteristics and verify the use of PPI with trial authors unless specifically stated in the published paper. The primary outcome will be the proportion of trials that use PPI. Secondary outcomes will explore which groups are consulted, at which stage of the trial process this occurs, and by what means these opinions are collected and implemented. DISCUSSION: This meta-epidemiological study will provide an important insight into the use of PPI in large, contemporary intensive care trials. We wish to reveal ways in which patient involvement could be incorporated more broadly and purposefully here and help to empower clinicians, researchers and patients to collaborate further on future research processes and goals.