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.

Platelet transfusions in adult thrombocytopenic ICU patients: Protocol for a sub-study of the PLOT-ICU cohort.

INTRODUCTION: Platelet transfusions are frequently used in intensive care unit (ICU) patients, but contemporary epidemiological data are sparse. We aim to present contemporary international data on the use of platelet transfusions in adult ICU patients with thrombocytopenia. METHODS: This is a protocol and statistical analysis plan for a post hoc sub-study of 504 thrombocytopenic patients from the 'Thrombocytopenia and platelet transfusions in ICU patients: an international inception cohort study (PLOT-ICU)'. The primary outcome will be the number of patients receiving platelet transfusion in the ICU reported according to the type of product received (apheresis-derived versus pooled whole-blood-derived transfusions). Secondary platelet transfusion outcomes will include platelet transfusion volumes; timing of platelet transfusion; approach to platelet transfusion dosing (fixed dosing versus weight-based dosing) and platelet count increments for prophylactic transfusions. Secondary clinical outcomes will include the number of patients receiving red blood cell- and plasma transfusions during ICU stay; the number of patients who bled in the ICU, the number of patients who had a new thrombosis in the ICU, and the number of patients who died. The duration of follow-up was 90 days. Baseline characteristics and secondary clinical outcomes will be stratified according to platelet transfusion status in the ICU and severity of thrombocytopenia. Data will be presented descriptively. CONCLUSIONS: The outlined study will provide detailed epidemiological data on the use of platelet transfusions in adult ICU patients with thrombocytopenia using data from the large international PLOT-ICU cohort study. The findings will inform the design of future randomised trials evaluating platelet transfusions in ICU patients.

Platelet transfusions in adult ICU patients with thrombocytopenia: A sub-study of the PLOT-ICU inception cohort study.

BACKGROUND: Platelet transfusions are frequently used in the intensive care unit (ICU), but current practices including used product types, volumes, doses and effects are unknown. STUDY DESIGN AND METHODS: Sub-study of the inception cohort study 'Thrombocytopenia and Platelet Transfusions in the ICU (PLOT-ICU)', including acutely admitted, adult ICU patients with thrombocytopenia (platelet count <150 × 109/L). The primary outcome was the number of patients receiving platelet transfusion in ICU by product type. Secondary outcomes included platelet transfusion details, platelet increments, bleeding, other transfusions and mortality. RESULTS: Amongst 504 patients with thrombocytopenia from 43 hospitals in 10 countries in Europe and the United States, 20.8% received 565 platelet transfusions; 61.0% received pooled products, 21.9% received apheresis products and 17.1% received both with a median of 2 (interquartile range 1-4) days from admission to first transfusion. The median volume per transfusion was 253 mL (180-308 mL) and pooled products accounted for 59.1% of transfusions, however, this varied across countries. Most centres (73.8%) used fixed dosing (medians ranging from 2.0 to 3.5 × 1011 platelets/transfusion) whilst some (mainly in France) used weight-based dosing (ranging from 0.5 to 0.7 × 1011 platelets per 10 kg body weight). The median platelet count increment for a single prophylactic platelet transfusion was 2 (-1 to 8) × 109/L. Outcomes of patients with thrombocytopenia who did and did not receive platelet transfusions varied. CONCLUSIONS: Among acutely admitted, adult ICU patients with thrombocytopenia, 20.8% received platelet transfusions in ICU of whom most received pooled products, but considerable variation was observed in product type, volumes and doses across countries. Prophylactic platelet transfusions were associated with limited increases in platelet counts.

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.

Platelet transfusions and thrombocytopenia in intensive care units: Protocol for an international inception cohort study (PLOT-ICU).

INTRODUCTION: Thrombocytopenia is frequent in intensive care unit (ICU) patients and has been associated with worse outcome. Platelet transfusions are often used in the management of ICU patients with severe thrombocytopenia. However, the reported frequencies of thrombocytopenia and platelet transfusion practices in the ICU vary considerably. Therefore, we aim to provide contemporary epidemiological data on thrombocytopenia and platelet transfusion practices in the ICU. METHODS: We will conduct an international inception cohort, including at least 1000 acutely admitted adult ICU patients. Routinely available data will be collected at baseline (ICU admission), and daily during ICU stay up to a maximum of 90 days. The primary outcome will be the number of patients with thrombocytopenia (a recorded platelet count < 150 × 109 /L) at baseline and/or during ICU stay. Secondary outcomes include mortality, days alive and out of hospital, days alive without life-support, the number of patients with at least one bleeding episode, at least one thromboembolic event and at least one platelet transfusion in the ICU, the number of platelet transfusions and the indications for transfusion. The primary and secondary outcomes will be presented descriptively. In addition, we will assess risk factors for developing thrombocytopenia during ICU stay and the association between thrombocytopenia at baseline and 90-day mortality using logistic regression analyses. CONCLUSION: The outlined international PLOT-ICU cohort study will provide contemporary epidemiological data on the burden and clinical significance of thrombocytopenia in adult ICU patients and describe the current platelet transfusion practice.

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 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.

Patient-important outcomes other than mortality in recent ICU trials: Protocol for a scoping review.

BACKGROUND: Randomised clinical trials (RCTs) conducted in intensive care units (ICUs) frequently focus on all-cause mortality, but other patient-important outcomes are increasingly used and recommended. Their use, however, is not straightforward: choices and definitions, operationalisation of death, handling of missing data, choice of effect measures, and statistical analyses for these outcomes vary greatly. METHODS: We will conduct a scoping review in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses Extension for Scoping Reviews. We will search 10 selected general and speciality journals for RCTs conducted in adult ICU patients from 2018 and onwards reporting at least 1 patient-important outcome other than mortality (including days alive without life support/days alive and out of hospital-type outcomes, health-related quality of life, functional/cognitive/neurological outcomes, and other general patient-important outcomes). We will summarise data on outcome measures and definitions, assessment time points, proportions and handling of death, proportions and handling of missing data, and effect measures and statistical methods used for analysis. DISCUSSION: The outlined scoping review will provide an overview of choices, definitions and handling of patient-important outcomes other than mortality in contemporary RCTs conducted in adult ICU patients. This may guide discussions with patients and relatives, the design of future RCTs, and research on optimal outcome choices and handling.

Bias and sample size in intensive care unit trials: Protocol for a meta-epidemiological study.

BACKGROUND: Systematic errors (bias) and random errors result in inflated and imprecise intervention effect estimates in randomised clinical trials (RCT) and meta-analyses. We aim to assess time trends in the Cochrane risk of bias domains and sample size in RCTs of intensive care unit (ICU) interventions. METHODS AND DESIGN: We will conduct a meta-epidemiologic study of RCTs included in Cochrane systematic reviews assessing any intervention used in adult patients admitted to the ICU. We will search the Cochrane Database of Systematic Reviews and include reviews published from March 2011 corresponding to the latest update in the Cochrane risk of bias tool. We will extract data on risk of bias judgments in the seven Cochrane bias domains and trial sample sizes and evaluate time trends using run charts. The primary outcome will be time trends in the annual proportion of trials with overall low risk of bias (low risk of bias in all bias domains). The secondary outcomes include time trends in the annual median trial sample size, and the annual proportion of trials with low-, unclear- and high risk of bias in each of the seven Cochrane bias domains. DISCUSSION: The outlined meta-epidemiologic study will assess time trends in risk of bias and sample sizes in RCTs assessing ICU interventions. This will inform researchers, healthcare personnel and policymakers on the general reliability of findings from RCTs of ICU interventions over time, and inform future RCT design and reporting.

Time to onset of gastrointestinal bleeding in the SUP-ICU trial: A pre-planned substudy.

BACKGROUND: The aetiology and risk factors for clinically important gastrointestinal bleeding (CIB) in adult ICU patients may differ according to the onset of CIB, which could affect the balance between benefits and harms of stress ulcer prophylaxis (SUP). METHODS: We assessed the time to CIB in the Stress Ulcer Prophylaxis in the Intensive Care Unit (SUP-ICU) trial. We assessed if associations between baseline characteristics including allocation to SUP and CIB changed during time in the ICU, specifically in the later (after day 2) compared to the earlier (first 2 days) period, using Cox models adjusted for SAPS II and allocation to SUP. Additionally, we described baseline characteristics and CIB episodes stratified by earlier/later/no CIB and 90-day mortality status. RESULTS: Clinically important gastrointestinal bleeding occurred in 110/3291 (3.3%) patients after a median of 6 (interquartile range 2-13) days; 25.5% of the episodes occurred early. Higher SAPS II was consistently associated with increased risk of CIB (hazard ratio (HR) 1.03, 95% confidence interval (CI) 1.01-1.05 in the earlier period vs HR 1.02, 95% CI 1.01-1.03 in the later period; P = .37); university hospital admission was associated with decreased risk of earlier CIB (HR 0.30, 95% CI 0.14-0.63); this significantly increased in the later period (to HR 0.85, 95% CI 0.53-1.37; P = .02). Patients with later compared to earlier CIB received more transfusions and had more diagnostic/therapeutic procedures for CIB. CONCLUSIONS: Clinically important gastrointestinal bleeding mostly occurred more than 2 days after randomization. University hospital admission was associated with significantly decreased risk of CIB in the earlier period only.

Thrombocytopenia and platelet transfusions in ICU patients: an international inception cohort study (PLOT-ICU).

PURPOSE: Thrombocytopenia (platelet count < 150 × 109/L) is common in intensive care unit (ICU) patients and is likely associated with worse outcomes. In this study we present international contemporary data on thrombocytopenia in ICU patients. METHODS: We conducted a prospective cohort study in adult ICU patients in 52 ICUs across 10 countries. We assessed frequencies of thrombocytopenia, use of platelet transfusions and clinical outcomes including mortality. We evaluated pre-selected potential risk factors for the development of thrombocytopenia during ICU stay and associations between thrombocytopenia at ICU admission and 90-day mortality using pre-specified logistic regression analyses. RESULTS: We analysed 1166 ICU patients; the median age was 63 years and 39.5% were female. Overall, 43.2% (95% confidence interval (CI) 40.4-46.1) had thrombocytopenia; 23.4% (20-26) had thrombocytopenia at ICU admission, and 19.8% (17.6-22.2) developed thrombocytopenia during their ICU stay. Absence of acquired immune deficiency syndrome (AIDS), non-cancer-related immune deficiency, liver failure, male sex, septic shock, and bleeding at ICU admission were associated with the development of thrombocytopenia during ICU stay. Among patients with thrombocytopenia, 22.6% received platelet transfusion(s), and 64.3% of in-ICU transfusions were prophylactic. Patients with thrombocytopenia had higher occurrences of bleeding and death, fewer days alive without the use of life-support, and fewer days alive and out of hospital. Thrombocytopenia at ICU admission was associated with 90-day mortality (adjusted odds ratio 1.7; 95% CI 1.19-2.42). CONCLUSION: Thrombocytopenia occurred in 43% of critically ill patients and was associated with worse outcomes including increased mortality. Platelet transfusions were given to 23% of patients with thrombocytopenia and most were prophylactic.

Overall bias and sample sizes were unchanged in ICU trials over time: a meta-epidemiological study.

OBJECTIVE: To assess time trends in risk of bias (RoB) and sample sizes in randomized clinical trials (RCTs) of adult intensive care unit (ICU) patients. STUDY DESIGN AND SETTING: A meta-epidemiological study of RCTs from Cochrane systematic reviews assessing interventions in adult ICU patients. Using run charts, we assessed time trends in the annual proportion of RCTs with overall low RoB, the annual median sample sizes, and the annual proportion of RCTs with low, unclear, and high RoB in individual bias domains. RESULTS: We included 604 RCTs published between 1977 and 2018 from 53 Cochrane systematic reviews. Only 6.8% of the RCTs had overall low RoB. We observed only random variation in the annual proportions of RCTs with overall low RoB, in the annual median sample sizes and in most individual bias domains. For "allocation concealment," we observed an increase in the proportion of low RoB RCTs and a decrease in the unclear RoB RCTs. CONCLUSIONS: Few RCTs in adult ICU patients had overall low RoB. We found no evidence of an increase in RCTs with overall low RoB or in the median sample sizes over time. The only individual RoB domain with better ratings over time was "allocation concealment."

Stress ulcer prophylaxis with proton pump inhibitors or histamin-2 receptor antagonists in adult intensive care patients: a systematic review with meta-analysis and trial sequential analysis.

PURPOSE: Most intensive care unit (ICU) patients receive stress ulcer prophylaxis. We present updated evidence on the effects of prophylactic proton pump inhibitors (PPIs) or histamine 2 receptor antagonists (H2RAs) versus placebo/no prophylaxis on patient-important outcomes in adult ICU patients. METHODS: We conducted a systematic review with meta-analysis and trial sequential analysis (TSA) of randomised clinical trials assessing the effects of PPI/H2RA versus placebo/no prophylaxis on mortality, gastrointestinal (GI) bleeding, serious adverse events (SAEs), health-related quality of life (HRQoL), myocardial ischemia, pneumonia, and Clostridium (Cl.) difficile enteritis in ICU patients. RESULTS: We identified 42 trials randomising 6899 ICU patients; 3 had overall low risk of bias. We did not find an effect of stress ulcer prophylaxis on mortality [relative risk 1.03, 95% confidence interval (CI) 0.94-1.14; TSA-adjusted CI 0.94-1.14], but the occurrence of any GI bleeding was reduced as compared with placebo/no prophylaxis (0.60, 95% CI 0.47-0.77; TSA-adjusted CI 0.36-1.00). The conventional meta-analysis indicated that clinically important GI bleeding was reduced (RR 0.63, 95% CI 0.48-0.81), but the TSA-adjusted CI 0.35-1.13 indicated lack of firm evidence. The effects of stress ulcer prophylaxis on SAEs, HRQoL, pneumonia, myocardial ischemia and Cl. difficile enteritis are uncertain. CONCLUSIONS: In this updated systematic review, we were able to refute a relative change of 20% of mortality. The occurrence of GI bleeding was reduced, but we lack firm evidence for a reduction in clinically important GI bleeding. The effects on SAEs, HRQoL, pneumonia, myocardial ischemia and Cl. difficile enteritis remain inconclusive.

No firm evidence that lack of blinding affects estimates of mortality in randomized clinical trials of intensive care interventions: a systematic review and meta-analysis.

OBJECTIVE: To evaluate the effect of blinding on mortality effect estimates in randomized clinical trials (RCTs) in adult intensive care unit (ICU) patients. STUDY DESIGN AND SETTING: A systematic review and meta-analysis of RCTs reporting mortality effect estimates of ICU interventions in adult ICU patients. We assessed differences in summarized risk ratios with 95% confidence intervals between blinded and unblinded RCTs. P < 0.10 was considered statistically significant (test of interaction). RESULTS: We included 22 ICU interventions assessed in 269 RCTs enrolling a total of 42,007 adult ICU patients in the primary analyses. We observed statistically significant differences between blinded and unblinded RCTs for all-cause mortality at longest follow-up in one of 22 interventions (5%), for in-hospital mortality in one of 12 interventions (8%) but not for in-ICU mortality. Combining all interventions, unblinded trials reported larger summary effect estimates on all-cause mortality at longest follow-up compared to blinded trials (test of interaction, P = 0.09). However, the difference was not statistically significant following adjustment for other risk of bias domains. CONCLUSIONS: We observed no firm evidence that lack of blinding affects estimates of mortality in RCTs of ICU interventions.

The effect of blinding on estimates of mortality in randomised clinical trials of intensive care interventions: protocol for a systematic review and meta-analysis.

INTRODUCTION: Evidence exists that unblinded randomised clinical trials (RCTs) overestimate intervention effects compared with blinded RCTs. It has been suggested that this is less pronounced for objective (ie, not subject to interpretation) outcome measures, including mortality. This may not apply in the intensive care unit (ICU), as most deaths are preceded by decisions to withhold or withdraw treatments. Lack of blinding of physicians in RCTs of ICU interventions may potentially influence the decision towards a higher threshold for discontinuing treatment in patients who receive the investigational treatment and/or a lower threshold for discontinuing treatment in patients who receive the comparator (control). This may have important implications for patients, caregivers, researchers and society. Accordingly, we aim to assess whether lack of blinding affects mortality effect estimates in RCTs of ICU interventions. METHODS AND ANALYSIS: We will conduct a systematic review with meta-analyses and assess the effect of blinding versus no blinding on mortality effect estimates in RCTs of interventions used in adult ICU patients.We will systematically search the Cochrane Library for systematic reviews reporting mortality effect estimates of any intervention used in adult ICU patients which includes at least one RCT with 'low risk of bias' in the bias domains 'blinding of participants and personnel' and/or 'blinding of outcome assessment' and one RCT with 'unclear' or 'high risk of bias' in the same bias domain(s). For each intervention, we will compare summary mortality effect estimates in blinded versus unblinded trials. ETHICS AND DISSEMINATION: This research does not require ethical approval as we will use summary data from trials already approved by relevant ethical institutions. We will report the results in accordance with the Preferred Reporting Items for Systematic Review and Meta-Analysis (PRISMA) statement and submit the final paper to an international peer-reviewed journal. TRIAL REGISTRATION NUMBER: PROSPERO, registration number: CRD42017056212.

Stress ulcer prophylaxis versus placebo or no prophylaxis in adult hospitalised acutely ill patients-protocol for a systematic review with meta-analysis and trial sequential analysis.

BACKGROUND: Stress ulcer prophylaxis is considered standard of care in many critically ill patients in the intensive care unit (ICU). However, the quality of evidence supporting this has recently been questioned, and clinical equipoise exists. Whether there is overall benefit or harm of stress ulcer prophylaxis in adult hospitalised acutely ill patients is unknown. Accordingly, we aim to assess patient-important benefits and harms of stress ulcer prophylaxis versus placebo or no treatment in adult hospitalised acutely ill patients with high risk of gastrointestinal bleeding irrespective of hospital setting. METHODS/DESIGN: We will conduct a systematic review of randomised clinical trials with meta-analysis and trial sequential analysis and assess use of proton pump inhibitors (PPIs) or histamine-2-receptor antagonists (H2RAs) in any dose, formulation and duration. We will accept placebo or no prophylaxis as control interventions. The participants will be adult hospitalised acutely ill patients with high risk of gastrointestinal bleeding. We will systematically search the Cochrane Library, MEDLINE, EMBASE, Science Citation Index, BIOSIS and Epistemonikos for relevant literature. We will follow the recommendations by the Cochrane Collaboration and the Preferred Reporting Items for Systematic Review and Meta-Analysis (PRISMA) statement. The risk of systematic errors (bias) and random errors will be assessed, and the overall quality of evidence will be evaluated using the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) approach. DISCUSSION: There is a need for a high-quality systematic review to summarise the benefits and harms of stress ulcer prophylaxis in hospitalised patients to inform practice and future research. Although stress ulcer prophylaxis is used worldwide, no firm evidence for benefit or harm as compared to placebo or no treatments has been established. Critical illness is a continuum not limited to the ICU setting, which is why it is important to assess the benefits and harms of stress ulcer prophylaxis in a wider perspective than exclusively in ICU patients. SYSTEMATIC REVIEW REGISTRATION: PROSPERO CRD42017055676.