Protocol and statistical analysis plan for the mega randomised registry trial comparing conservative vs. liberal oxygenation targets in adults in the intensive care unit with suspected hypoxic ischaemic encephalopathy following a cardiac arrest (Mega-ROX HIE).

Background: The effect of conservative vs. liberal oxygen therapy on 90-day in-hospital mortality in adults with hypoxic ischaemic encephalopathy (HIE) following a cardiac arrest who are receiving invasive mechanical ventilation in the intensive care unit (ICU) is uncertain. Objective: To summarise the protocol and statistical analysis plan for the Mega-ROX HIE trial. Design setting and participants: Mega-ROX HIE is an international randomised clinical trial that will be conducted within an overarching 40,000-participant registry-embedded clinical trial comparing conservative and liberal ICU oxygen therapy regimens. We expect to enrol approximately 4000 participants with suspected HIE following a cardiac arrest who are receiving invasive mechanical ventilation in the ICU. Main outcome measures: The primary outcome is in-hospital all-cause mortality up to 90 days from the date of randomisation. Secondary outcomes include duration of survival, duration of mechanical ventilation, ICU length of stay, hospital length of stay, and the proportion of participants discharged home. Results and conclusions: Mega-ROX HIE will compare the effect of conservative vs. liberal oxygen therapy regimens on day-90 in-hospital mortality in adults in the ICU with suspected HIE following a cardiac arrest. The protocol and planned analyses are reported here to mitigate analysis bias. Trial registration: Australian and New Zealand Clinical Trials Registry (ACTRN 12620000391976).

The Effects of Early-Phase, Low- or Standard-Intensity Continuous Renal Replacement Therapy on Acid-Base Control and Clinical Outcomes: An Observational Study.

INTRODUCTION: The Kidney Disease Improving Global Outcomes (KDIGO) clinical practice guideline recommends administering an effluent volume of 20-25 mL/kg/h during continuous renal replacement therapy (CRRT) for acute kidney injury. Recent evidence on CRRT initiation showed that less intervention might be beneficial for renal recovery. This study aimed to explore the association between early-phase low CRRT intensity and acid-base balance corrections and clinical outcomes. METHODS: This was a single-centre, retrospective, observational study at a tertiary intensive care unit (ICU) in Japan. All adult patients requiring CRRT in the ICU were included. Eligible patients were classified into the Low group (dialysate flow rate [QD] 10.0-19.9 mL/kg/h) and the Standard group (QD ≥20 mL/kg/h) by the intensity of CRRT at the beginning. The primary outcomes were acid-base parameters 6 h after CRRT initiation. We used an inverse probability of treatment weighting analysis to estimate the association between the intensity group and the outcomes. RESULTS: Overall, 194 patients were classified into the Low group (n = 144) and the Standard group (n = 50). The Standard group presented with more severe acid-base disturbances, including lower pH and base excess (BE) at baseline. At 6 h after CRRT initiation, pH, BE, and strong ion difference values were comparable, even after adjusting for baseline severity. Despite the efficient correction, no evident differences were observed in clinical outcomes between the two groups. CONCLUSIONS: The initial standard intensity appeared to be efficient in correcting acid-base imbalance at the early phase of CRRT; however, further studies are needed to assess the impact on clinical outcomes.

From ICU Syndromes to ICU Subphenotypes: Consensus Report and Recommendations for Developing Precision Medicine in the ICU.

Critical care uses syndromic definitions to describe patient groups for clinical practice and research. There is growing recognition that a "precision medicine" approach is required and that integrated biologic and physiologic data identify reproducible subpopulations that may respond differently to treatment. This article reviews the current state of the field and considers how to successfully transition to a precision medicine approach. To impact clinical care, identification of subpopulations must do more than differentiate prognosis. It must differentiate response to treatment, ideally by defining subgroups with distinct functional or pathobiological mechanisms (endotypes). There are now multiple examples of reproducible subpopulations of sepsis, acute respiratory distress syndrome, and acute kidney or brain injury described using clinical, physiological, and/or biological data. Many of these subpopulations have demonstrated the potential to define differential treatment response, largely in retrospective studies, and that the same treatment-responsive subpopulations may cross multiple clinical syndromes (treatable traits). To bring about a change in clinical practice, a precision medicine approach must be evaluated in prospective clinical studies requiring novel adaptive trial designs. Several such studies are underway, but there are multiple challenges to be tackled. Such subpopulations must be readily identifiable and be applicable to all critically ill populations around the world. Subdividing clinical syndromes into subpopulations will require large patient numbers. Global collaboration of investigators, clinicians, industry, and patients over many years will therefore be required to transition to a precision medicine approach and ultimately realize treatment advances seen in other medical fields.

Dose of nafamostat mesylate during continuous kidney replacement therapy in critically ill patients: a two-centre observational study.

BACKGROUND: Nafamostat mesylate is an anticoagulant used for critically ill patients during continuous kidney replacement therapy (CKRT), characterised by its short half-life. However, its optimal dosage remains unclear. This study aimed to explore the optimal dosage of nafamostat mesylate during CKRT. METHODS: We conducted a two-centre observational study. We screened all critically ill adult patients who required CKRT in the intensive care unit (ICU) from September 2013 to August 2021; we included patients aged ≥ 18 years who received nafamostat mesylate during CKRT. The primary outcome was filter life, defined as the time from CKRT initiation to the end of the first filter use due to filter clotting. The secondary outcomes included safety and other clinical outcomes. The survival analysis of filter patency by the nafamostat mesylate dosage adjusted for bleeding risk and haemofiltration was performed using a Cox proportional hazards model. RESULTS: We included 269 patients. The mean dose of nafamostat mesylate was 15.8 mg/hr (Standard deviation (SD), 8.8; range, 5.0 to 30.0), and the median filter life was 18.3 h (Interquartile range (IQR), 9.28 to 36.7). The filter survival analysis showed no significant association between the filter life and nafamostat mesylate dosage (hazard ratio 1.12; 95 CI 0.74-1.69, p = 0.60) after adjustment for bleeding risk and addition of haemofiltration to haemodialysis. CONCLUSIONS: We observed no dose-response relationship between the dose of nafamostat mesylate (range: 5 to 30 mg/h) and the filter life during CKRT in critically ill patients. The optimal dose to prevent filter clotting safely needs further study in randomised controlled trials. TRIAL REGISTRATION: Not applicable.

Optimal timing for intubation in patients on non-invasive ventilation: A retrospective cohort study.

Background and Aims: The timing of transition from non-invasive ventilation (NIV) to invasive ventilation in the intensive care unit (ICU) is uncertain due to a lack of clinical evidence. This study aimed to identify the optimal timing of intubation in patients with respiratory failure managed with NIVs. Methods: A single-center observational study was conducted in Tokyo, Japan. Patients in the ICU managed with NIV between 2013 and 2022 were screened. The primary outcome was 28-day invasive ventilator-free days. Statistical analyses used locally estimated scatter plot smoothing (LOESS) and generalized linear mixed models to estimate the association between the timing of transition and prolonged intubation duration. Results: During the study period, 139 of 589 adult ICU patients receiving NIV transitioned to invasive ventilation. The LOESS curve indicated the longest 28-day ventilator-free days around 24 h after NIV initiation, after which the primary outcome decreased linearly. Late intubation after 24 h of NIV initiation was associated with fewer 28-day ventilator-free days (adjusted mean difference: -0.22 days [95% confidence interval: -0.31, -0.13]). Conclusion: We identified a non-linear association between the timing of intubation and 28-day invasive ventilator-free days. The critical 24-h time window for patients on NIV was associated with longer 28-day invasive ventilator-free days.

Protocol and statistical analysis plan for the mega randomised registry trial comparing conservative vs. liberal oxygenation targets in adults with sepsis in the intensive care unit (Mega-ROX Sepsis).

Background: The effect of conservative vs. liberal oxygen therapy on 90-day in-hospital mortality in adults with sepsis receiving unplanned invasive mechanical ventilation in the intensive care unit (ICU) is uncertain. Objective: The objective of this study was to summarise the protocol and statistical analysis plan for the Mega-ROX Sepsis trial. Design setting and participants: The Mega-ROX Sepsis trial is an international randomised clinical trial that will be conducted within an overarching 40,000-patient registry-embedded clinical trial comparing conservative and liberal ICU oxygen therapy regimens. We anticipate that between 10,000 and 13,000 patients with sepsis who are receiving unplanned invasive mechanical ventilation in the ICU will be enrolled in this trial. Main outcome measures: The primary outcome is in-hospital all-cause mortality up to 90 days from the date of randomisation. Secondary outcomes include duration of survival, duration of mechanical ventilation, ICU length of stay, hospital length of stay, and the proportion of patients discharged home. Results and conclusions: Mega-ROX Sepsis will compare the effect of conservative vs. liberal oxygen therapy on 90-day in-hospital mortality in adults with sepsis who are receiving unplanned invasive mechanical ventilation in the ICU. The protocol and a prespecified approach to analyses are reported here to mitigate analysis bias.

Protocol and statistical analysis plan for the mega randomised registry trial comparing conservative vs. liberal oxygenation targets in adults with nonhypoxic ischaemic acute brain injuries and conditions in the intensive care unit (Mega-ROX Brains).

Background: The effect of conservative vs. liberal oxygen therapy on 90-day in-hospital mortality in adults who have nonhypoxic ischaemic encephalopathy acute brain injuries and conditions and are receiving invasive mechanical ventilation in the intensive care unit (ICU) is uncertain. Objective: The objective of this study was to summarise the protocol and statistical analysis plan for the Mega-ROX Brains trial. Design setting and participants: Mega-ROX Brains is an international randomised clinical trial, which will be conducted within an overarching 40,000-participant, registry-embedded clinical trial comparing conservative and liberal ICU oxygen therapy regimens. We expect to enrol between 7500 and 9500 participants with nonhypoxic ischaemic encephalopathy acute brain injuries and conditions who are receiving unplanned invasive mechanical ventilation in the ICU. Main outcome measures: The primary outcome is in-hospital all-cause mortality up to 90 d from the date of randomisation. Secondary outcomes include duration of survival, duration of mechanical ventilation, ICU length of stay, hospital length of stay, and the proportion of participants discharged home. Results and conclusions: Mega-ROX Brains will compare the effect of conservative vs. liberal oxygen therapy regimens on 90-day in-hospital mortality in adults in the ICU with acute brain injuries and conditions. The protocol and planned analyses are reported here to mitigate analysis bias. Trial Registration: Australian and New Zealand Clinical Trials Registry (ACTRN 12620000391976).

Factors associated with non-initiation of osteoporosis pharmacotherapy after hip fracture: analysis of claims data in Japan.

In an analysis of claims data from a city in Japan, male patients and patients with dementia were less likely to receive osteoporosis pharmacotherapy after hip fracture. Treatment initiation rate has improved between 2014 and 2017. PURPOSE: Older adults with recent hip fractures are at a high risk of recurrent fractures. However, the post-fracture care gap has been reported globally. This study examines factors associated with pharmacotherapy non-initiation within 1 year after hip surgery. METHODS: Using medical and long-term care (LTC) claims, and LTC needs certification data in Tsukuba City, Japan, we identified individuals aged 65 years or older who had hip fractures with subsequent surgical procedures between October 1, 2014, and December 31, 2017. Patient (age, sex, dementia, and comorbidities) and health service-related characteristics (fiscal year, type of hospital, number of hospital beds, and admission to recovery phase rehabilitation wards) were examined. The association of these factors with non-pharmacotherapy for osteoporosis within 1 year after hip fracture using multivariable logistic models was analyzed. RESULTS: We identified 275 patients with hip fractures who did not receive pharmacotherapy pre-fracture. Forty percent of them received pharmacotherapy within 1 year of post-fracture. Male sex (odds ratio (OR) = 4.49 [2.14-9.44]) and dementia (OR = 1.90 [1.03-3.52]) were associated with no pharmacotherapy, whereas later fiscal year (OR = 0.64 [0.48-0.87]) and admission to rehabilitation wards (OR = 0.25 [0.14-0.46]) were associated with pharmacotherapy initiation within 1 year of post-fracture. Comorbidities were not associated with the initiation of pharmacotherapy. CONCLUSION: Pharmacotherapy for osteoporosis was less likely to be initiated after a hip fracture in male patients and patients with dementia. These patients should be considered for pharmacotherapy because they are at high risk of recurrent fractures.

Intravenous vitamin C therapy in adult patients with sepsis: A rapid practice guideline.

BACKGROUND: This Rapid Practice Guideline provides an evidence-based recommendation to address the question: in adults with sepsis or septic shock, should we recommend using or not using intravenous vitamin C therapy? METHODS: The panel included 21 experts from 16 countries and used a strict policy for potential financial and intellectual conflicts of interest. Methodological support was provided by the Guidelines in Intensive Care, Development, and Evaluation (GUIDE) group. Based on an updated systematic review, and the grading of recommendations, assessment, development, and evaluation approach, we evaluated the certainty of evidence and developed recommendations using the evidence-to-decision framework. We conducted an electronic vote, requiring >80% agreement among the panel for a recommendation to be adopted. RESULTS: At longest follow-up, 90 days, intravenous vitamin C probably does not substantially impact (relative risk 1.05, 95% confidence interval [CI] 0.94 to 1.17; absolute risk difference 1.8%, 95% CI -2.2 to 6.2; 6 trials, n = 2148, moderate certainty). Effects of vitamin C on mortality at earlier timepoints was of low or very low certainty due to risk of bias of the included studies and significant heterogeneity between study results. Few adverse events were reported with the use of vitamin C. The panel did not identify any major differences in other outcomes, including duration of mechanical ventilation, ventilator free days, hospital or intensive care unit length of stay, acute kidney injury, need for renal replacement therapy. Vitamin C may result in a slight reduction in duration of vasopressor support (MD -18.9 h, 95% CI -26.5 to -11.4; 21 trials, n = 2661, low certainty); but may not reduce sequential organ failure assessment scores (MD -0.69, 95% CI -1.55 to 0.71; 24 trials, n = 4002, low certainty). The panel judged the undesirable consequences of using IV vitamin C to probably outweigh the desirable consequences, and therefore issued a conditional recommendation against using IV vitamin C therapy in sepsis. CONCLUSIONS: The panel suggests against use of intravenous vitamin C in adult patients with sepsis, beyond that of standard nutritional supplementation. Small and single center trials on this topic should be discouraged.

Sodium Bicarbonate for Metabolic Acidosis in the ICU: Results of a Pilot Randomized Double-Blind Clinical Trial.

OBJECTIVES: To identify the best population, design of the intervention, and to assess between-group biochemical separation, in preparation for a future phase III trial. DESIGN: Investigator-initiated, parallel-group, pilot randomized double-blind trial. SETTING: Eight ICUs in Australia, New Zealand, and Japan, with participants recruited from April 2021 to August 2022. PATIENTS: Thirty patients greater than or equal to 18 years, within 48 hours of admission to the ICU, receiving a vasopressor, and with metabolic acidosis (pH < 7.30, base excess [BE] < -4 mEq/L, and Pa co2 < 45 mm Hg). INTERVENTIONS: Sodium bicarbonate or placebo (5% dextrose). MEASUREMENTS AND MAIN RESULT: The primary feasibility aim was to assess eligibility, recruitment rate, protocol compliance, and acid-base group separation. The primary clinical outcome was the number of hours alive and free of vasopressors on day 7. The recruitment rate and the enrollment-to-screening ratio were 1.9 patients per month and 0.13 patients, respectively. Time until BE correction (median difference, -45.86 [95% CI, -63.11 to -28.61] hr; p < 0.001) and pH correction (median difference, -10.69 [95% CI, -19.16 to -2.22] hr; p = 0.020) were shorter in the sodium bicarbonate group, and mean bicarbonate levels in the first 24 hours were higher (median difference, 6.50 [95% CI, 4.18 to 8.82] mmol/L; p < 0.001). Seven days after randomization, patients in the sodium bicarbonate and placebo group had a median of 132.2 (85.6-139.1) and 97.1 (69.3-132.4) hours alive and free of vasopressor, respectively (median difference, 35.07 [95% CI, -9.14 to 79.28]; p = 0.131). Recurrence of metabolic acidosis in the first 7 days of follow-up was lower in the sodium bicarbonate group (3 [20.0%] vs. 15 [100.0%]; p < 0.001). No adverse events were reported. CONCLUSIONS: The findings confirm the feasibility of a larger phase III sodium bicarbonate trial; eligibility criteria may require modification to facilitate recruitment.

Update on the management of acute respiratory failure using non-invasive ventilation and pulse oximetry.

This article is one of ten reviews selected from the Annual Update in Intensive Care and Emergency Medicine 2023. Other selected articles can be found online at  https://www.biomedcentral.com/collections/annualupdate2023 . Further information about the Annual Update in Intensive Care and Emergency Medicine is available from  https://link.springer.com/bookseries/8901 .

Intravenous ravulizumab in mechanically ventilated patients hospitalised with severe COVID-19: a phase 3, multicentre, open-label, randomised controlled trial.

BACKGROUND: The complement pathway is a potential target for the treatment of severe COVID-19. We evaluated the safety and efficacy of ravulizumab, a terminal complement C5 inhibitor, in patients hospitalised with severe COVID-19 requiring invasive or non-invasive mechanical ventilation. METHODS: This phase 3, multicentre, open-label, randomised controlled trial (ALXN1210-COV-305) enrolled adult patients (aged ≥18 years) from 31 hospitals in France, Japan, Spain, the UK, and the USA. Eligible patients had a confirmed diagnosis of SARS-CoV-2 that required hospitalisation and either invasive or non-invasive mechanical ventilation, with severe pneumonia, acute lung injury, or acute respiratory distress syndrome confirmed by CT scan or x-ray. We randomly assigned participants (2:1) to receive intravenous ravulizumab plus best supportive care (BSC) or BSC alone using a web-based interactive response system. Randomisation was in permuted blocks of six with stratification by intubation status. Bodyweight-based intravenous doses of ravulizumab were administered on days 1, 5, 10, and 15. The primary efficacy endpoint was survival based on all-cause mortality at day 29 in the intention-to-treat (ITT) population. Safety endpoints were analysed in all randomly assigned patients in the ravulizumab plus BSC group who received at least one dose of ravulizumab, and in all randomly assigned patients in the BSC group. The trial is registered with ClinicalTrials.gov, NCT04369469, and was terminated at interim analysis due to futility. FINDINGS: Between May 10, 2020, and Jan 13, 2021, 202 patients were enrolled in the study and randomly assigned to ravulizumab plus BSC or BSC. 201 patients were included in the ITT population (135 in the ravulizumab plus BSC group and 66 in the BSC group). The ravulizumab plus BSC group comprised 96 (71%) men and 39 (29%) women with a mean age of 63·2 years (SD 13·23); the BSC group comprised 43 (65%) men and 23 (35%) women with a mean age of 63·5 years (12·40). Most patients (113 [84%] of 135 in the ravulizumab plus BSC group and 53 [80%] of 66 in the BSC group) were on invasive mechanical ventilation at baseline. Overall survival estimates based on multiple imputation were 58% for patients receiving ravulizumab plus BSC and 60% for patients receiving BSC (Mantel-Haenszel analysis: risk difference -0·0205; 95% CI -0·1703 to 0·1293; one-sided p=0·61). In the safety population, 113 (89%) of 127 patients in the ravulizumab plus BSC group and 56 (84%) of 67 in the BSC group had a treatment-emergent adverse event. Of these events, infections and infestations (73 [57%] vs 24 [36%] patients) and vascular disorders (39 [31%] vs 12 [18%]) were observed more frequently in the ravulizumab plus BSC group than in the BSC group. Five patients had serious adverse events considered to be related to ravulizumab. These events were bacteraemia, thrombocytopenia, oesophageal haemorrhage, cryptococcal pneumonia, and pyrexia (in one patient each). INTERPRETATION: Addition of ravulizumab to BSC did not improve survival or other secondary outcomes. Safety findings were consistent with the known safety profile of ravulizumab in its approved indications. Despite the lack of efficacy, the study adds value for future research into complement therapeutics in critical illnesses by showing that C5 inhibition can be accomplished in severely ill patients. FUNDING: Alexion, AstraZeneca Rare Disease.

Unfractionated heparin versus nafamostat mesylate for anticoagulation during continuous kidney replacement therapy: an observational study.

BACKGROUND: Unfractionated heparin sodium and nafamostat mesylate have long been used as anticoagulants in continuous kidney replacement therapy (CKRT) where citrate is unavailable. This study aimed to determine whether heparin or nafamostat mesylate used during CKRT was associated with a longer filter life. METHODS: In this single-centre observational study, we included adult patients who required CKRT and used heparin or nafamostat mesylate for their first CKRT in the intensive care unit from September 1, 2013, to December 31, 2020. The primary outcome was filter life (from the start to the end of using the first filter). We used propensity score matching to adjust for the imbalance in patients' characteristics and laboratory data at the start of CKRT and compared the outcomes between the two groups. We also performed restricted mean survival time analysis to compare the filter survival times. RESULTS: We included 286 patients, 157 patients on heparin and 129 patients on nafamostat mesylate. After propensity score matching, the mean filter life with heparin was 1.58 days (N = 91, Standard deviation [SD], 1.52) and with nafamostat mesylate was 1.06 days (N = 91, SD, 0.94, p = 0.006). Multivariable regression analysis adjusted for confounding factors supported that heparin was associated with a longer filter life compared with nafamostat mesylate (regression coefficient, days, 0.52 [95% CI, 0.15, 0.89]). The between group difference of the restricted mean filter survival time in the matched cohort was 0.29 (95% CI, 0.07-0.50, p = 0.008). CONCLUSION: Compared to nafamostat mesylate, heparin was associated with one-third to one-half a day longer filter life. TRIAL REGISTRATION: Not applicable.

Thromboembolic events in hospitalised patients with COVID-19: ecological assessment with a scoping review.

OBJECTIVES: Thrombosis is a common complication of the novel COVID-19. Pre-COVID-19 studies reported racial differences in the risk of developing thrombosis. This study aimed to describe the geographical variations in the reported incidences and outcomes of thromboembolic events and thromboprophylaxis in hospitalised patients with COVID-19. The final search for randomised clinical trials was carried out in January 2022. Screening eligible articles and data extraction were independently performed in duplicate by multiple reviewers. DESIGN: Scoping review. MEDLINE, Embase, Cochrane Libraries were searched using terms related to COVID-19 and thromboembolism. SETTING: Hospitals all over the world. PARTICIPANTS: In-hospital patients with COVID-19. OUTCOME MEASURES: The incidence of deep venous thrombosis (DVT) and pulmonary embolism (PE), and the prophylactic anticoagulation therapy. RESULTS: In total, 283 studies were eligible, representing (239 observational studies, 39 case series and 7 interventional studies). The incidence of DVT was the highest in Asia (40.8%) and hospital mortality was high (22.7%). However, the incidence of PE was not very high in Asia (3.2%). On the contrary, the incidence of PE was the highest in the Middle East (16.2%) and Europe (14. 6%). Prophylactic anticoagulation therapy with low-molecular-weight heparin was the main treatment provided in all areas. Four of the seven randomised clinical trials were conducted internationally. CONCLUSIONS: The incidence of DVT was the highest in Asia. The incidence of PE was higher in the Middle East and Europe; however, detection bias during the pandemic cannot be ruled out. There were no major differences in the type or dose of prophylactic anticoagulants used for thromboprophylaxis among the regions.

The Sequential Organ Failure Assessment (SOFA) Score: has the time come for an update?

The Sequential Organ Failure Assessment (SOFA) score was developed more than 25 years ago to provide a simple method of assessing and monitoring organ dysfunction in critically ill patients. Changes in clinical practice over the last few decades, with new interventions and a greater focus on non-invasive monitoring systems, mean it is time to update the SOFA score. As a first step in this process, we propose some possible new variables that could be included in a SOFA 2.0. By so doing, we hope to stimulate debate and discussion to move toward a new, properly validated score that will be fit for modern practice.

Proportion attributable to contextual effects in general medicine: a meta-epidemiological study based on Cochrane reviews.

OBJECTIVES: Our objectives were to examine the magnitude of the proportion attributable to contextual effects (PCE), which shows what proportion of the treatment arm response can be achieved by the placebo arm across various interventions, and to examine PCE variability by outcome type and condition. DESIGN: We conducted a meta-epidemiological study. SETTING: We searched the Cochrane Database of Systematic Reviews with the keyword 'placebo' in titles, abstracts and keywords on 1 January 2020. PARTICIPANTS: We included reviews that showed statistically significant beneficial effects of the intervention over placebo for the first primary outcome. MAIN OUTCOME MEASURES: We performed a random-effects meta-analysis to calculate PCEs based on the pooled result of each included review, grouped by outcome type and condition. The PCE quantifies how much of the observed treatment response can be achieved by the contextual effects. PUBLIC AND PATIENT INVOLVEMENT STATEMENT: No patient or member of the public was involved in conducting this research. RESULTS: We included 328 out of 3175 Cochrane systematic reviews. The results of meta-analyses showed that PCEs varied greatly depending on outcome type (I2=98%) or condition (I2=98%), but mostly lie between 0.40 and 0.95. Overall, the PCEs were 0.65 (95% CI 0.59 to 0.72) on average. Subjective outcomes were 0.50 (95% CI 0.41 to 0.59), which was significantly smaller than those of semiobjective (PCE 0.78; 95% CI 0.72 to 0.85) or objective outcomes (PCE 0.94; 95% CI 0.91 to 0.97). CONCLUSIONS: The results suggest that much of the observed benefit is not just due to the specific effect of the interventions. The specific effects of interventions may be larger for subjective outcomes than for objective or semiobjective outcomes. However, PCEs were exceptionally variable. When we evaluate the magnitude of PCEs, we should consider each PCE individually, for each condition, intervention and outcome in its context, to assess the importance of an intervention for each specific clinical setting.