How outcomes are defined in clinical trials of mechanically ventilated adults and children

Development of a core outcome set for ventilation trials in neurocritical care patients with acute brain injury: protocol for a Delphi consensus study of international stakeholders

INTRODUCTION

There is little consensus and high heterogeneity on the optimal set of relevant clinical outcomes in research studies regarding extubation in neurocritical care patients with brain injury undergoing mechanical ventilation. The aims of this study are to: (1) develop a core outcome set (COS) and (2) reach consensus on a hierarchical composite endpoint for such studies.

METHODS AND ANALYSIS

The study will include a broadly representative, international panel of stakeholders with research and clinical expertise in this field and will involve four stages: (1) a scoping review to generate an initial list of outcomes represented in the literature, (2) an investigator meeting to review the outcomes for inclusion in the Delphi surveys, (3) four rounds of online Delphi consensus-building surveys and (4) online consensus meetings to finalise the COS and hierarchical composite endpoint.

ETHICS AND DISSEMINATION

This study received ethical approval from the French Society of Anesthesia and Critical Care Medicine Institutional Review Board (SFAR CERAR-IRB 00010254-2023-029). The study results will be disseminated through communication to stakeholders, publication in a peer-reviewed journal, and presentations at conferences.

TRIAL REGISTRATION NUMBER

This study is registered with the Core Outcome Measures in Effectiveness Trials (COMET) Initiative.

Heterogeneity of surrogate outcome measures used in critical care studies: A systematic review

BACKGROUND

The choice of outcome measure is a critical decision in the design of any clinical trial, but many Phase III clinical trials in critical care fail to detect a difference between the interventions being compared. This may be because the surrogate outcomes used to show beneficial effects in early phase trials (which informed the design of the subsequent Phase III trials) are not valid guides to the differences between the interventions for the main outcomes of the Phase III trials. We undertook a systematic review (1) to generate a list of outcome measures used in critical care trials, (2) to determine the variability in the outcome reporting in the respiratory subgroup and (3) to create a smaller list of potential early phase endpoints in the respiratory subgroup.

METHODS

Data related to outcomes were extracted from studies published in the six top-ranked critical care journals between 2010 and 2020. Outcomes were classified into subcategories and categories. A subset of early phase endpoints relevant to the respiratory subgroup was selected for further investigation. The variability of the outcomes and the variability in reporting was investigated.

RESULTS

A total of 6905 references were retrieved and a total of 294 separate outcomes were identified from 58 studies. The outcomes were then classified into 11 categories and 66 subcategories. A subset of 22 outcomes relevant for the respiratory group were identified as potential early phase outcomes. The summary statistics, time points and definitions show the outcomes are analysed and reported in different ways.

CONCLUSION

The outcome measures were defined, analysed and reported in a variety of ways. This creates difficulties for synthesising data in systematic reviews and planning definitive trials. This review once again highlights an urgent need for standardisation and validation of surrogate outcomes reported in critical care trials. Future work should aim to validate and develop a core outcome set for surrogate outcomes in critical care trials.

Evaluation of outcome reporting in clinical trials of physiotherapy in bronchiectasis: The first stage of core outcome set development

INTRODUCTION

The aim of this study is to explore outcomes currently reported in physiotherapy trials for bronchiectasis and investigate the level of consistency in outcome reporting. This mapping of outcomes will be used to inform the development of a core outcome set (COS) for physiotherapy research in bronchiectasis. Outcomes reported in randomised clinical trials (RCTs) and RCT protocols were reviewed and evaluated. We included trials with physiotherapy as the main intervention, including pulmonary rehabilitation, exercise prescription, airway clearance, positive expiratory pressure devices, breathing training, self-management plans, and home exercise program. Medline, CINAHL, Scopus, Cochrane Central Register of Controlled Trials (CENTRAL), and the physiotherapy evidence database (PEDro) were searched from inception using a prespecified search strategy. Records including adult patients with bronchiectasis were included. Outcomes were listed verbatim and categorised into domains based on a pre-specified system, frequency of reporting and sources of variation were inspected.

RESULTS

Of 2158 abstracts screened, 37 trials (1202 participants) and 17 trial protocols were identified. Eighteen different physiotherapy techniques were investigated. A total of 331 outcomes were reported. No single outcome was reported by all trials. The most reported outcomes were lung function (27 trials, 50%), health related quality of life (26 trials, 48.1%), and dyspnoea (18 trials, 33.3%). A list of 104 unique outcomes covering 23 domains was created. Trials focus on physiological outcomes, mainly those related to respiratory system functions. Outcomes related to functioning and life impact are often neglected.

CONCLUSION

Outcome reporting in physiotherapy research for bronchiectasis was found to be inconsistent in terms of choosing and defining outcomes. Developing a core outcome set in this area of research is needed to facilitate aggregation of future trial results in systematic reviews that will in turn inform the strength of evidence for the effectiveness of physiotherapy. Outcome choice should include all stakeholders, including patients.

TRIAL REGISTRATION

This study is registered in the PROSPERO registry under the number CRD42021266247.

Re-analysis of ventilator-free days (VFD) in acute respiratory distress syndrome (ARDS) studies

BACKGROUND

Over recent decades, improvements in healthcare have reduced mortality and morbidity rates in many conditions. This has resulted, in part, from the identification of effective interventions in randomised trials, and in conducting such trials, a composite outcome measure (COM) with multiple components will increase event rates, which allows study completion with a smaller sample size. In critical care research, the COM "ventilator-free days" (VFD) combines mortality and duration of mechanical ventilation (MV) into a single continuous measure, which can be analysed in a variety of ways. This study investigates the usefulness of Poisson and two-part Poisson models compared to t-distribution for the analysis of VFD.

METHODS

Data from four studies (ALbuterol for the Treatment of ALI (ALTA), Early vs. Delayed Enteral Nutrition (EDEN), Hydroxymethylglutaryl-CoA reductase inhibition with simvastatin in Acute Lung Injury (ALI) to reduce pulmonary dysfunction (HARP-2), Statins for Acutely Injured Lungs from Sepsis (SAILS)) were used for analysis, with the VFD results summarised using mean, standard deviation (SD), median, interquartile range (25th and 75th percentiles) and minimum and maximum values. The statistical analyses that are compared used the t-test, Poisson, zero-inflated Poisson (ZIP) and two-part Logit-Poisson hurdle models. The analyses were exploratory in nature, and the significance level for differences in the estimates was set to 0.05.

RESULTS

In HARP-2, which compared simvastatin and placebo, the mean (SD) VFD for all patients was 12.0 (10.2), but this mean value did not represent the data distribution as it falls in a zone between two peaks, with the lowest frequency of occurrence. The mean (SD) VFD after excluding patients who died before day 28 and patients who did not achieve unassisted breathing were 15.9 (8.7) and 18.2 (6.6), respectively. The mean difference (95% CI) between the two groups was 1.1 (95% CI: 0.7 to 2.8; p = 0.20) based on an independent t-test. However, when the two-part hurdle model was used, the simvastatin arm had a significantly higher number of non-zero values compared to the placebo group, which indicated that more patients were alive and free of mechanical ventilation in the simvastatin group. Similarly, in ALTA, this model found that significantly more patients were alive and free of MV in the control group. In EDEN and SAILS, there was no significant difference between the control and intervention groups.

CONCLUSION

Our analyses show that the t-test and Poisson model are not appropriate for bi-modal data (such as VFD) where there is a large number of zero events. The two-part hurdle model was the most promising approach. There is a need for future research to investigate other analysis techniques, such as two-part quantile regression and to determine the impact on sample size requirements for comparative effectiveness trials.

A Core Outcome Set for Critical Care Ventilation Trials

Supplemental Digital Content is available in the text.

Our objective was to obtain international consensus on a set of core outcome measures that should be recorded in all clinical trials of interventions intended to modify the duration of ventilation for invasively mechanically ventilated patients in the ICU.

Reporting of Organ Support Outcomes in Septic Shock Randomized Controlled Trials: A Methodologic Review-The Sepsis Organ Support Study

OBJECTIVES

Many recent randomized controlled trials in the field of septic shock failed to demonstrate a benefit on mortality. Randomized controlled trials increasingly report organ support duration and organ support-free days as primary or secondary outcomes. We conducted a methodologic systematic review to assess how organ support outcomes were defined and reported in septic shock randomized controlled trials.

DATA SOURCES

MEDLINE via PubMed, Embase, Cochrane Central Register of Controlled Trials, and Web of Science.

STUDY SELECTION

We included randomized controlled trials published between January 2004 and March 2018 that involved septic shock adults and assessed organ support duration and/or organ support-free days for hemodynamic support, respiratory support, or renal replacement therapy.

DATA EXTRACTION

For each randomized controlled trial, we extracted the definitions of organ support duration and organ support-free days. We particularly evaluated how nonsurvivors were accounted for. Study authors were contacted to provide any missing information regarding these definitions.

DATA SYNTHESIS

We included 28 randomized controlled trials. Organ support duration and organ support-free days outcomes were reported in 17 and 15 randomized controlled trials, respectively, for hemodynamic support, 15 and 15 for respiratory support, and five and nine for renal replacement therapy. Nonsurvivors were included in the organ support duration calculation in 13 of 14 randomized controlled trials (93%) for hemodynamic support and nine of 10 (90%) for respiratory support. The organ support-free days definition for hemodynamic support, respiratory support, and renal replacement therapy was reported in six of 15 randomized controlled trials (40%), eight of 15 randomized controlled trials (53%), and six of nine randomized controlled trials (67%) reporting an organ support-free days outcome, respectively. Of these, one half assigned "0" to nonsurvivors, and the other half attributed one point per day alive free of organ support up to a predefined time point.

CONCLUSIONS

This study highlights the heterogeneity and infrequency of organ support duration/organ support-free days outcome reporting in septic shock trials. When reported, the definitions of these outcome measures and methods of calculation are also infrequently reported, in particular how nonsurvivors were accounted for, which may have an important impact on interpretation.

Contemporary strategies to improve clinical trial design for critical care research: insights from the First Critical Care Clinical Trialists Workshop

BACKGROUND

Conducting research in critically-ill patient populations is challenging, and most randomized trials of critically-ill patients have not achieved pre-specified statistical thresholds to conclude that the intervention being investigated was beneficial.

METHODS

In 2019, a diverse group of patient representatives, regulators from the USA and European Union, federal grant managers, industry representatives, clinical trialists, epidemiologists, and clinicians convened the First Critical Care Clinical Trialists (3CT) Workshop to discuss challenges and opportunities in conducting and assessing critical care trials. Herein, we present the advantages and disadvantages of available methodologies for clinical trial design, conduct, and analysis, and a series of recommendations to potentially improve future trials in critical care.

CONCLUSION

The 3CT Workshop participants identified opportunities to improve critical care trials using strategies to optimize sample size calculations, account for patient and disease heterogeneity, increase the efficiency of trial conduct, maximize the use of trial data, and to refine and standardize the collection of patient-centered and patient-informed outcome measures beyond mortality.

Review of Outcomes Used in Nutrition Trials in Pediatric Critical Care

BACKGROUND

Generating robust evidence within pediatric intensive care (PIC) can be challenging because of low patient numbers and patient heterogeneity. Systematic reviews may overcome small study biases but are limited by lack of standardization in outcome measures and their definition. Trials of nutrition interventions in PIC are increasing; thus, we wanted to examine the outcome measures being used in these trials.

OBJECTIVE

Our objective was to systematically describe outcome measures used when a nutrition intervention has been evaluated in a PIC randomized controlled trial.

METHODS

A systematic literature review of all studies involving a PIC trial of a nutrition intervention was undertaken from January 1, 1996, until February 20, 2018.

RESULTS

Twenty-nine trials met the criteria and were reviewed. They included a total of 3226 patients across all trials. Thirty-seven primary outcomes and 83 secondary outcomes were found. These were categorized into PIC-related outcomes (infection, intensive care dependency, organ dysfunction, and mortality) and nutrition outcomes (energy targets, nutrition parameters, and feeding tolerance). We found large variation in the outcome measures used. Outcome domains of energy targets, feeding tolerance, and infection were not adequately defined.

CONCLUSIONS

Considerable variation in the outcome measures chosen and their definitions exist within PIC nutrition trials. Optimal nutrition outcomes for PIC must be agreed upon and defined, specifically domains of nutrition efficiency, nutrition tolerance, and non-nutrition PIC outcomes. The next step is to conduct an international Delphi study to gain expert consensus and develop a core outcome set to be reported in future pediatric nutrition trials.

Cut-Off Values of the Post-Intensive Care Syndrome Questionnaire for the Screening of Unplanned Hospital Readmission within One Year

PURPOSE

This study aimed to assign weights for subscales and items of the Post-Intensive Care Syndrome questionnaire and suggest optimal cut-off values for screening unplanned hospital readmissions of critical care survivors.

METHODS

Seventeen experts participated in an analytic hierarchy process for weight assignment. Participants for cut-off analysis were 240 survivors who had been admitted to intensive care units for more than 48 hours in three cities in Korea. We assessed participants using the 18-item Post-Intensive Care Syndrome questionnaire, generated receiver operating characteristic curves, and analysed cut-off values for unplanned readmission based on sensitivity, specificity, and positive likelihood ratios.

RESULTS

Cognitive, physical, and mental subscale weights were 1.13, 0.95, and 0.92, respectively. Incidence of unplanned readmission was 25.4%. Optimal cut-off values were 23.00 for raw scores and 23.73 for weighted scores (total score 54.00), with an area of under the curve (AUC) of .933 and .929, respectively. There was no significant difference in accuracy for original and weighted scores.

CONCLUSION

The optimal cut-off value accuracy is excellent for screening of unplanned readmissions. We recommend that nurses use the Post-Intensive Care Syndrome Questionnaire to screen for readmission risk or evaluating relevant interventions for critical care survivors.

Measuring and Analyzing Length of Stay in Critical Care Trials

BACKGROUND

In randomized clinical trials among critically ill patients, it is uncertain how choices regarding the measurement and analysis of nonmortal outcomes measured in terms of duration, such as intensive care unit (ICU) length of stay (LOS), affect studies' conclusions.

OBJECTIVES

Assess the definitions and analytic methods used for ICU LOS analyses in published randomized clinical trials.

RESEARCH DESIGN

This is a systematic review and statistical simulation study.

RESULTS

Among the 80 of 150 trials providing sufficient information regarding the chosen definition of ICU LOS, 3 different start times (ICU admission, trial enrollment/randomization, receipt of intervention) and 2 end times (discharge readiness, actual discharge) were used. In roughly three quarters of these studies, ICU LOS was compared using approaches that did not explicitly account for death, either by ignoring it entirely or stratifying the analyses by survival status. The remaining studies used time-to-event (discharge) models censoring at death or applied a fixed LOS value to patients who died. In statistical simulations, we showed that each analytic approach tested a different question regarding ICU LOS, and that approaches that do not explicitly account for death often produce misleading or ambiguous conclusions when treatments produce small effects on mortality, even if those are not detected as significant in the trial.

CONCLUSIONS

There is considerable variability in how ICU LOS is measured and analyzed which impairs the ability to compare results across trials and can produce spurious conclusions. Analyses of duration-based outcomes such as LOS should jointly assess the impact of the intervention on mortality to yield correct interpretations.

Ventilator-Free Day Outcomes Can Be Misleading

INTRODUCTION

Acute respiratory distress syndrome often requires invasive mechanical ventilation, with both mortality and mechanical ventilation duration as outcomes of interest. The concept of ventilator-free days has been proposed as an outcome combining these two outcomes. Here we analyzed the construction of the ventilator-free day outcome and provided a hypothetical scenario to alert physicians that such an outcome can lead to misleading interpretations.

METHODS

We proposed the isoventilator-free day curve concept and, using an analytical development, illustrated how a median ventilator-free day value can actually result from very different combinations of death rates and mechanical ventilation durations. We also used a hypothetical example to compare the Student t test, Wilcoxon rank-sum test, and Gray test (which accounts for death as a competing event with extubation) in comparing exposition to mechanical ventilation.

RESULTS

A median ventilator-free day value of 10 days may mean that 10% of the patients died while survivors were ventilated during a median of 14 days or that 40% died while survivors were ventilated during a median of 5 days. Changing the time horizon affected the Student t test but not the Wilcoxon rank-sum result. The Gray test was more relevant than both the Student t test and Wilcoxon rank-sum test in identifying differences in groups showing highly different mechanical ventilation duration, despite equal median ventilator-free days. This approach was also illustrated using real data.

CONCLUSIONS

Use of ventilator-free days as an outcome appears to have many drawbacks. Suitable methods of analyzing time to extubation should be preferred.

Stakeholder Engagement in Trial Design: Survey of Visitors to Critically Ill Patients Regarding Preferences for Outcomes and Treatment Options during Weaning from Mechanical Ventilation

RATIONALE

Stakeholder engagement in research is expected to provide unique insights, make research investments more accountable and transparent, and ensure that future research is applicable to patients and family members.

OBJECTIVES

To inform the design of a trial of strategies for weaning from mechanical ventilation, we sought to identify preferences of patient visitors regarding outcome and treatment measures.

METHODS

We conducted an interviewer-administered questionnaire of visitors of critically ill patients in two family waiting rooms serving three intensive care units (ICUs) in Toronto, Canada. Respondents rated the importance of general and ventilation-related outcomes in two hypothetical scenarios (before a first spontaneous breathing trial, and after a failed spontaneous breathing trial) and selected a preferred technique for the breathing trials. With regard to the patient they were visiting, respondents identified the most important outcome to them at ICU admission, during the ICU stay, and at ICU discharge.

MEASUREMENTS AND MAIN RESULTS

We analyzed 322 questionnaires (95.5% response rate). All outcomes were highly rated (average range: 7.82-9.74). Across scenarios, outcomes rated as most important were ICU and hospital survival (9.72, 9.70), avoiding complications (9.45), quality of life (9.394), patient comfort (9.393), and returning to previous living arrangements (9.31). Overall, the most important ventilation-related outcomes were being ventilator-free (8.95), avoiding reintubation (8.905), and passing a spontaneous breathing trial (8.903). Passing a spontaneous breathing trial assumed greater importance after an initial failed attempt. "Time to event" outcomes were less important to visitors. We did not identify a preferred spontaneous breathing trial technique. Although ICU survival was the most important outcome at ICU admission and during the ICU stay, visitors rated quality of life higher than hospital survival at ICU discharge.

CONCLUSIONS

Visitors to critically ill patients prioritized two general outcomes (ICU and hospital survival) and three ventilation-related outcomes (being ventilator free, avoiding reintubation, passing a spontaneous breathing trial), and valued avoiding complications, maintaining quality of life, comfort, and returning to previous living arrangements. The outcomes preferences of the survey respondents evolved temporally during the ICU stay.

Supplemental Oxygen-Free Days in Hematopoietic Cell Transplant Recipients With Respiratory Syncytial Virus

Background

Clinically meaningful endpoints for respiratory syncytial virus (RSV) treatment trials are lacking for hematopoietic cell transplant (HCT) recipients. We evaluated supplemental oxygen use among HCT recipients with RSV infection.

Methods

Subjects were grouped according to the presence of upper respiratory tract infection (URTI) without lower respiratory tract infection (LRTI), URTI progressing to LRTI, and LRTI at presentation. LRTI was defined as a positive lower respiratory tract sample with or without radiographic abnormality (defined as proven or probable LRTI, respectively) or a positive upper respiratory tract sample with radiographic abnormality (possible LRTI). Supplemental oxygen–free days were defined as any day while alive after diagnosis of RSV infection during which ≤2 L of supplemental oxygen per minute was received.

Results

Among 230 patients, supplemental oxygen use by day 28 after the first diagnosis of RSV infection was lowest in patients presenting with URTI (31 of 197 [16%]). Supplemental oxygen use was lower in patients with possible LRTI (12 of 45 [27%]) than in those with proven/probable LRTI (29 of 42 [69%]). Patients presenting with proven/probable LRTI had a median of 16 fewer supplemental oxygen–free days than those presenting with URTI (P < .0001). Death only occurred among patients with proven/probable LRTI (11 of 42 [26%]).

Conclusions

Confirmation of RSV infection in the lower respiratory tract provides prognostic information that may help prioritize therapies. Supplemental oxygen–free days as a clinical endpoint may allow smaller sample sizes for trials evaluating RSV antivirals.

Duration of Postoperative Mechanical Ventilation as a Quality Metric for Pediatric Cardiac Surgical Programs

BACKGROUND

Few metrics exist to assess quality of care at pediatric cardiac surgical programs, limiting opportunities for benchmarking and quality improvement. Postoperative duration of mechanical ventilation (POMV) may be an important quality metric because of its association with complications and resource utilization. In this study we modelled case-mix-adjusted POMV duration and explored hospital performance across POMV metrics.

METHODS

This study used the Pediatric Cardiac Critical Care Consortium clinical registry to analyze 4,739 hospitalizations from 15 hospitals (October 2013 to August 2015). All patients admitted to pediatric cardiac intensive care units after an index cardiac operation were included. We fitted a model to predict duration of POMV accounting for patient characteristics. Robust estimates of SEs were obtained using bootstrap resampling. We created performance metrics based on observed-to-expected (O/E) POMV to compare hospitals.

RESULTS

Overall, 3,108 patients (65.6%) received POMV; the remainder were extubated intraoperatively. Our model was well calibrated across groups; neonatal age had the largest effect on predicted POMV. These comparisons suggested clinically and statistically important variation in POMV duration across centers with a threefold difference observed in O/E ratios (0.6 to 1.7). We identified 1 hospital with better-than-expected and 3 hospitals with worse-than-expected performance (p < 0.05) based on the O/E ratio.

CONCLUSIONS

We developed a novel case-mix-adjusted model to predict POMV duration after congenital heart operations. We report variation across hospitals on metrics of O/E duration of POMV that may be suitable for benchmarking quality of care. Identifying high-performing centers and practices that safely limit the duration of POMV could stimulate quality improvement efforts.

Comparison of Clinical Trial and Systematic Review Outcomes for the 4 Most Prevalent Eye Diseases

Importance

Suboptimal overlap in outcomes reported in clinical trials and systematic reviews compromises efforts to compare and summarize results across these studies.

Objectives

To examine the most frequent outcomes used in trials and reviews of the 4 most prevalent eye diseases (age-related macular degeneration [AMD], cataract, diabetic retinopathy [DR], and glaucoma) and the overlap between outcomes in the reviews and the trials included in the reviews.

Design, Setting, and Participants

This cross-sectional study examined all Cochrane reviews that addressed AMD, cataract, DR, and glaucoma; were published as of July 20, 2016; and included at least 1 trial and the trials included in the reviews. For each disease, a pair of clinical experts independently classified all outcomes and resolved discrepancies. Outcomes (outcome domains) were then compared separately for each disease.

Main Outcomes and Measures

Proportion of review outcomes also reported in trials and vice versa.

Results

This study included 56 reviews that comprised 414 trials. Although the median number of outcomes per trial and per review was the same (n = 5) for each disease, the trials included a greater number of outcomes overall than did the reviews, ranging from 2.9 times greater (89 vs 30 outcomes for glaucoma) to 4.9 times greater (107 vs 22 outcomes for AMD). Most review outcomes, ranging from 14 of 19 outcomes (73.7%) (for DR) to 27 of 29 outcomes (93.1%) (for cataract), were also reported in the trials. For trial outcomes, however, the proportion also named in reviews was low, ranging from 19 of 107 outcomes (17.8%) (for AMD) to 24 of 89 outcomes (27.0%) (for glaucoma). Only 1 outcome (visual acuity) was consistently reported in greater than half the trials and greater than half the reviews.

Conclusions and Relevance

Although most review outcomes were reported in the trials, most trial outcomes were not reported in the reviews. The current analysis focused on outcome domains, which might underestimate the problem of inconsistent outcomes. Other important elements of an outcome (ie, specific measurement, specific metric, method of aggregation, and time points) might have differed even though the domains overlapped. Inconsistency in trial outcomes may impede research synthesis and indicates the need for disease-specific core outcome sets in ophthalmology.

Extubation Failure in Brain-injured Patients: Risk Factors and Development of a Prediction Score in a Preliminary Prospective Cohort Study

BACKGROUND

The decision to extubate brain-injured patients with residual impaired consciousness holds a high degree of uncertainty of success. The authors developed a pragmatic clinical score predictive of extubation failure in brain-injured patients.

METHODS

One hundred and forty brain-injured patients were prospectively included after the first spontaneous breathing trial success. Assessment of multiparametric hemodynamic, respiratory, and neurologic functions was performed just before extubation. Extubation failure was defined as the need for ventilatory support during intensive care unit stay. Extubation failure within 48 h was also analyzed. Neurologic outcomes were recorded at 6 months.

RESULTS

Extubation failure occurred in 43 (31%) patients with 31 (24%) within 48 h. Predictors of extubation failure consisted of upper-airway functions (cough, gag reflex, and deglutition) and neurologic status (Coma Recovery Scale-Revised visual subscale). From the odds ratios, a four-item predictive score was developed (area under the curve, 0.85; 95% CI, 0.77 to 0.92) and internally validated by bootstrap. Cutoff was determined with sensitivity of 92%, specificity of 50%, positive predictive value of 82%, and negative predictive value of 70% for extubation failure. Failure before and beyond 48 h shared similar risk factors. Low consciousness level patients were extubated with 85% probability of success providing the presence of at least two operating airway functions.

CONCLUSIONS

A simplified clinical pragmatic score assessing cough, deglutition, gag reflex, and neurologic status was developed in a preliminary prospective cohort of brain-injured patients and was internally validated (bootstrapping). Extubation appears possible, providing functioning upper airways and irrespective of neurologic status. Clinical practice generalizability urgently needs external validation.

Variations in Case-Mix-Adjusted Duration of Mechanical Ventilation Among ICUs

OBJECTIVES

To develop a model that predicts the duration of mechanical ventilation and then to use this model to compare observed versus expected duration of mechanical ventilation across ICUs.

DESIGN

Retrospective cohort analysis.

SETTING

Eighty-six eligible ICUs at 48 U.S. hospitals.

PATIENTS

ICU patients receiving mechanical ventilation on day 1 (n = 56,336) admitted from January 2013 to September 2014.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

We developed and validated a multivariable logistic regression model for predicting duration of mechanical ventilation using ICU day 1 patient characteristics. Mean observed minus expected duration of mechanical ventilation was then obtained across patients and for each ICU. The accuracy of the model was assessed using R. We defined better performing units as ICUs that had an observed minus expected duration of mechanical ventilation less than -0.5 days and a p value of less than 0.01; and poorer performing units as ICUs with an observed minus expected duration of mechanical ventilation greater than +0.5 days and a p value of less than 0.01. The factors accounting for the majority of the model's explanatory power were diagnosis (71%) and physiologic abnormalities (24%). For individual patients, the difference between observed and mean predicted duration of mechanical ventilation was 3.3 hours (95% CI, 2.8-3.9) with R equal to 21.6%. The mean observed minus expected duration of mechanical ventilation across ICUs was 3.8 hours (95% CI, 2.1-5.5), with R equal to 69.9%. Among the 86 ICUs, 66 (76.7%) had an observed mean mechanical ventilation duration that was within 0.5 days of predicted. Five ICUs had significantly (p < 0.01) poorer performance (observed minus expected duration of mechanical ventilation, > 0.5 d) and 14 ICUs significantly (p < 0.01) better performance (observed minus expected duration of mechanical ventilation, < -0.5 d).

CONCLUSIONS

Comparison of observed and case-mix-adjusted predicted duration of mechanical ventilation can accurately assess and compare duration of mechanical ventilation across ICUs, but cannot accurately predict an individual patient's mechanical ventilation duration. There are substantial differences in duration of mechanical ventilation across ICU and their association with unit practices and processes of care warrants examination.

Clinical trials in acute respiratory distress syndrome: challenges and opportunities

This year is the 50th anniversary of the first description of acute respiratory distress syndrome (ARDS). Since then, much has been learned about the pathogenesis of lung injury in ARDS, with an emphasis on the mechanisms of injury to the lung endothelium and the alveolar epithelium. In terms of treatment, major progress has been made in reducing mortality from ARDS with lung-protective ventilation, using a tidal volume of 6 mL per kg of predicted bodyweight and a plateau airway pressure of less than 30 cm H₂O. In more severely hypoxaemic patients with ARDS, neuromuscular blockade and prone positioning have further reduced mortality, probably by extending the therapeutic effects of lung protective ventilation. Fluid-conservative therapy has also increased ventilator-free days in patients with ARDS. The lack of success of pharmacological therapies for ARDS, however, presents a continued challenge in the field. In addition to presenting a brief summary of previous experience with clinical trials in ARDS, we focus in this Review on future opportunities to improve clinical trial design to maximise the likelihood of identifying beneficial pharmacological therapies. In view of the heterogeneity in ARDS, both prognostic and predictive enrichment strategies are needed that target therapies toward specific subgroups of patients with ARDS on the basis of both severity and biology. Approaches to reducing heterogeneity in ARDS clinical trials include using physiological, radiographic, and biological criteria to select patients for both phase 2 and 3 trials. Additionally, interest is growing in the design of preventive clinical trials in ARDS and to initiate early treatment of patients with acute lung injury before the need for endotracheal intubation. We also present promising new approaches to treating ARDS, including combination therapies, cell-based therapies, and generic pharmacological compounds with low-risk profiles that are already in routine clinical use for other clinical indications.

Conservative fluid management or deresuscitation for patients with sepsis or acute respiratory distress syndrome following the resuscitation phase of critical illness: a systematic review and meta-analysis

BACKGROUND

It is unknown whether a conservative approach to fluid administration or deresuscitation (active removal of fluid using diuretics or renal replacement therapy) is beneficial following haemodynamic stabilisation of critically ill patients.

PURPOSE

To evaluate the efficacy and safety of conservative or deresuscitative fluid strategies in adults and children with acute respiratory distress syndrome (ARDS), sepsis or systemic inflammatory response syndrome (SIRS) in the post-resuscitation phase of critical illness.

METHODS

We searched Medline, EMBASE and the Cochrane central register of controlled trials from 1980 to June 2016, and manually reviewed relevant conference proceedings from 2009 to the present. Two reviewers independently assessed search results for inclusion and undertook data extraction and quality appraisal. We included randomised trials comparing fluid regimens with differing fluid balances between groups, and observational studies investigating the relationship between fluid balance and clinical outcomes.

RESULTS

Forty-nine studies met the inclusion criteria. Marked clinical heterogeneity was evident. In a meta-analysis of 11 randomised trials (2051 patients) using a random-effects model, we found no significant difference in mortality with conservative or deresuscitative strategies compared with a liberal strategy or usual care [pooled risk ratio (RR) 0.92, 95 % confidence interval (CI) 0.82-1.02, I 2 = 0 %]. A conservative or deresuscitative strategy resulted in increased ventilator-free days (mean difference 1.82 days, 95 % CI 0.53-3.10, I 2 = 9 %) and reduced length of ICU stay (mean difference -1.88 days, 95 % CI -0.12 to -3.64, I 2 = 75 %) compared with a liberal strategy or standard care.

CONCLUSIONS

In adults and children with ARDS, sepsis or SIRS, a conservative or deresuscitative fluid strategy results in an increased number of ventilator-free days and a decreased length of ICU stay compared with a liberal strategy or standard care. The effect on mortality remains uncertain. Large randomised trials are needed to determine optimal fluid strategies in critical illness.

Are physical measures related to patient-centred outcomes in ARDS survivors?

OBJECTIVE

To inform selection of physical measures for studies of acute respiratory distress syndrome (ARDS) survivors within 12 months of ARDS.

METHODS

Secondary analysis of data from 6-month survivors participating in a US multicentre prospective study (ARDSNet Long-Term Outcome Study, N=134) or a multisite prospective study in Baltimore, Maryland, USA (Improving Care of Acute Lung Injury Patients, N=99). Physical measures, assessed at 6-month follow-up, were categorised according to the WHO's International Classification of Disability and Health: body functions and structures, activity and participation. Patient-centred outcomes were evaluated at 6 and 12 months: survival, hospitalisation, alive at home status and health-related quality of life. Pearson correlation, linear and logistic regression models were used to quantify associations of physical measures with patient-centred outcomes.

MAIN RESULTS

No 6-month body functions and structures measure demonstrated consistent association with 6-month or 12-month outcomes in multivariable regression. The 6 min walk test, an activity measure, was associated with 6-month Short-Form 36 (SF-36) physical component scores (PCS, β range: 0.99 to 1.52, p<0.05). Participation measures (Functional Performance Inventory, FPI; Instrumental Activities of Daily Living, IADLs) were associated with SF-36 PCS (β range: FPI, 1.51-1.52; IADL, -1.88 to -1.32; all p<0.05) and Euro-QOL-5D utility score (β range: FPI, 2.00-3.67; IADL, -2.89 to -2.50; all p<0.01) at 6 and 12 months.

CONCLUSIONS

Participation measures better reflect patient's quality of life than measures of body functions and structures within 12 months of ARDS among 6-month survivors, and are recommended for inclusion as a core measure in future studies.

Alpha-2 agonists for sedation of mechanically ventilated adults in intensive care units: a systematic review

BACKGROUND

Care of critically ill patients in intensive care units (ICUs) often requires potentially invasive or uncomfortable procedures, such as mechanical ventilation (MV). Sedation can alleviate pain and discomfort, provide protection from stressful or harmful events, prevent anxiety and promote sleep. Various sedative agents are available for use in ICUs. In the UK, the most commonly used sedatives are propofol (Diprivan(®), AstraZeneca), benzodiazepines [e.g. midazolam (Hypnovel(®), Roche) and lorazepam (Ativan(®), Pfizer)] and alpha-2 adrenergic receptor agonists [e.g. dexmedetomidine (Dexdor(®), Orion Corporation) and clonidine (Catapres(®), Boehringer Ingelheim)]. Sedative agents vary in onset/duration of effects and in their side effects. The pattern of sedation of alpha-2 agonists is quite different from that of other sedatives in that patients can be aroused readily and their cognitive performance on psychometric tests is usually preserved. Moreover, respiratory depression is less frequent after alpha-2 agonists than after other sedative agents.

OBJECTIVES

To conduct a systematic review to evaluate the comparative effects of alpha-2 agonists (dexmedetomidine and clonidine) and propofol or benzodiazepines (midazolam and lorazepam) in mechanically ventilated adults admitted to ICUs.

DATA SOURCES

We searched major electronic databases (e.g. MEDLINE without revisions, MEDLINE In-Process & Other Non-Indexed Citations, EMBASE and Cochrane Central Register of Controlled Trials) from 1999 to 2014.

METHODS

Evidence was considered from randomised controlled trials (RCTs) comparing dexmedetomidine with clonidine or dexmedetomidine or clonidine with propofol or benzodiazepines such as midazolam, lorazepam and diazepam (Diazemuls(®), Actavis UK Limited). Primary outcomes included mortality, duration of MV, length of ICU stay and adverse events. One reviewer extracted data and assessed the risk of bias of included trials. A second reviewer cross-checked all the data extracted. Random-effects meta-analyses were used for data synthesis.

RESULTS

Eighteen RCTs (2489 adult patients) were included. One trial at unclear risk of bias compared dexmedetomidine with clonidine and found that target sedation was achieved in a higher number of patients treated with dexmedetomidine with lesser need for additional sedation. The remaining 17 trials compared dexmedetomidine with propofol or benzodiazepines (midazolam or lorazepam). Trials varied considerably with regard to clinical population, type of comparators, dose of sedative agents, outcome measures and length of follow-up. Overall, risk of bias was generally high or unclear. In particular, few trials blinded outcome assessors. Compared with propofol or benzodiazepines (midazolam or lorazepam), dexmedetomidine had no significant effects on mortality [risk ratio (RR) 1.03, 95% confidence interval (CI) 0.85 to 1.24, I (2) = 0%; p = 0.78]. Length of ICU stay (mean difference -1.26 days, 95% CI -1.96 to -0.55 days, I (2) = 31%; p = 0.0004) and time to extubation (mean difference -1.85 days, 95% CI -2.61 to -1.09 days, I (2) = 0%; p < 0.00001) were significantly shorter among patients who received dexmedetomidine. No difference in time to target sedation range was observed between sedative interventions (I (2) = 0%; p = 0.14). Dexmedetomidine was associated with a higher risk of bradycardia (RR 1.88, 95% CI 1.28 to 2.77, I (2) = 46%; p = 0.001).

LIMITATIONS

Trials varied considerably with regard to participants, type of comparators, dose of sedative agents, outcome measures and length of follow-up. Overall, risk of bias was generally high or unclear. In particular, few trials blinded assessors.

CONCLUSIONS

Evidence on the use of clonidine in ICUs is very limited. Dexmedetomidine may be effective in reducing ICU length of stay and time to extubation in critically ill ICU patients. Risk of bradycardia but not of overall mortality is higher among patients treated with dexmedetomidine. Well-designed RCTs are needed to assess the use of clonidine in ICUs and identify subgroups of patients that are more likely to benefit from the use of dexmedetomidine.

STUDY REGISTRATION

This study is registered as PROSPERO CRD42014014101.

FUNDING

The National Institute for Health Research Health Technology Assessment programme. The Health Services Research Unit is core funded by the Chief Scientist Office of the Scottish Government Health and Social Care Directorates.

Confronting the frustrations of negative clinical trials in acute respiratory distress syndrome

Despite robust successes in trials of mechanical ventilation, pharmacologic interventions in acute respiratory distress syndrome have been disappointing. Although ineffective therapy remains the compelling explanation for these negative trials, other possible explanations exist. These negative trials, better termed "statistically negative trials" or "indeterminate trials," cannot prove that a therapy is ineffective. It is important for clinicians and investigators to appreciate the alternative explanations for negative trials of potentially effective therapies because these indicate options for improving clinical trials in acute respiratory distress syndrome. These options can be organized into strategies that increase sample size, increase the signal from the therapy, and reduce the noise or variation in the study. Each of the strategies to improve the likelihood of a positive clinical trial poses a potential tradeoff in generalizability, cost, sample size, signal, or noise.

Parents' and young people's involvement in designing a trial of ventilator weaning

Consulting with users is considered best practice and is highly recommended in designing new trials. As part of our feasibility work, we undertook a consultation exercise with parents, ex-patients and young people prior to designing a trial of protocol-based ventilator weaning. Our aims were to (1) ascertain views on the relevance and importance of the trial; (2) determine the important parent/patient outcome measures; and (3) ascertain views on informed consent in a cluster randomized controlled trial. We conducted audio-recorded face-to-face, telephone and focus group interviews with parents and young people. Data were content analysed to generate information to address our specific consultation objectives. The setting was the north-western region of England. A total of 16 participants were interviewed: 2 parents of paediatric intensive care unit (PICU) survivors; 1 PICU survivor; and 13 young people from the former Medicines for Children Research Network. The trial objectives were deemed important and relevant, and participants considered the most important outcome measure to be the length of time on ventilation. Parents and young people did not consider written informed consent to be a necessary requirement in the context of this trial, rather awareness of unit participation in the trial was important with the opportunity of opting out of data collection. This consultation provided useful, pragmatic insights to inform trial design. We encountered significant challenges in recruiting parents and young people for this consultation exercise, and novel recruitment methods need to be considered for future work in this field. Patient and public involvement is essential to ensure that future trials answer parent-relevant questions and have meaningful outcome measures, as well as involving parents and young people in the general development of health care services.

Core Outcomes in Ventilation Trials (COVenT): protocol for a core outcome set using a Delphi survey with a nested randomised trial and observational cohort study

BACKGROUND

Among clinical trials of interventions that aim to modify time spent on mechanical ventilation for critically ill patients there is considerable inconsistency in chosen outcomes and how they are measured. The Core Outcomes in Ventilation Trials (COVenT) study aims to develop a set of core outcomes for use in future ventilation trials in mechanically ventilated adults and children.

METHODS/DESIGN

We will use a mixed methods approach that incorporates a randomised trial nested within a Delphi study and a consensus meeting. Additionally, we will conduct an observational cohort study to evaluate uptake of the core outcome set in published studies at 5 and 10 years following core outcome set publication. The three-round online Delphi study will use a list of outcomes that have been reported previously in a review of ventilation trials. The Delphi panel will include a range of stakeholder groups including patient support groups. The panel will be randomised to one of three feedback methods to assess the impact of the feedback mechanism on subsequent ranking of outcomes. A final consensus meeting will be held with stakeholder representatives to review outcomes.

DISCUSSION

The COVenT study aims to develop a core outcome set for ventilation trials in critical care, explore the best Delphi feedback mechanism for achieving consensus and determine if participation increases use of the core outcome set in the long term.

Is critical care ready for an economic surrogate endpoint?

Intensive care is expensive, and thus a body of research has focused on strategies to reduce its costs. However, efforts to reduce the total cost of intensive care have met with limited success, partly because of the challenges of calculating how much a day in the ICU actually costs. We discuss these challenges and introduce the concept of total cost savings as an outcome of critical care trials, assuming statistically negative effects on mortality and quality of life.

Intensive care diaries to promote recovery for patients and families after critical illness: A Cochrane Systematic Review

OBJECTIVES

To assess the effect of an intensive care unit (ICU) diary versus no ICU diary on patients, and their caregivers or families, during the patient's recovery from admission to an ICU.

DESIGN

Systematic review of randomized controlled trials (RCTs) and clinical controlled trials.

DATA SOURCES

CENTRAL, MEDLINE, CINAHL, EMBASE, PsycINFO, PILOT; Web of Science Conference Proceedings, clinical trial registries and reference lists of identified trials.

REVIEW METHODS

Studies evaluated the effectiveness of patient diaries, when compared to no ICU diary, for patients or family members to promote recovery after admission to ICU were included. Outcome measures for describing recovery from ICU included the risk of post-traumatic stress disorder (PTSD), anxiety, depression and post-traumatic stress symptomatology, health-related quality of life and costs. We used standard methodological approaches as expected by The Cochrane Collaboration. Two review authors independently reviewed titles for inclusion, extracted data and undertook risk of bias according to pre-specified criteria.

RESULTS

We identified three eligible studies; two describing ICU patients (N=358), and one describing relatives of ICU patients (N=30). No study adequately reported on risk of PTSD as described using a clinical interview, family or caregiver anxiety or depression, health-related quality of life or costs. Within a single study there was no clear evidence of a difference in risk for developing anxiety (RR 0.29, 95% CI 0.07-1.19) or depression (RR 0.38, 95% CI 0.12-1.19) in participants who received ICU diaries, in comparison to those that did not receive a patient diary. Within a single study there was no evidence of difference in median post-traumatic stress symptomatology scores (diaries 24, SD 11.6; no diary 24, SD 11.6) and delusional ICU memory recall (RR 1.04, 95% CI 0.84-1.28) between the patients recovering from ICU admission who received patient diaries, and those who did not. One study reported reduced post-traumatic stress symptomatology in family members of patients recovering from admission to ICU who received patient diaries (median 19; range 14-28), in comparison to no diary (median 28; range 14-38).

CONCLUSIONS

Currently there is minimal evidence from RCTs of the benefits or harms of patient diaries for patients and their caregivers or family members. A small study has described their potential to reduce post-traumatic stress symptomatology in family members. However, there is currently inadequate evidence to support their effectiveness in improving psychological recovery after critical illness for patients and their family members.

Predictive models of prolonged mechanical ventilation yield moderate accuracy

PURPOSE

To develop a model to predict prolonged mechanical ventilation within 48 hours of its initiation.

MATERIALS AND METHODS

In 282 general intensive care unit patients, multiple variables from the first 2 days on mechanical ventilation and their total ventilation duration were prospectively collected. Three models accounting for early deaths were developed using different analyses: (a) multinomial logistic regression to predict duration > 7 days vs duration ≤ 7 days alive vs duration ≤ 7 days death; (b) binary logistic regression to predict duration > 7 days for the entire cohort and for survivors only, separately; and (c) Cox regression to predict time to being free of mechanical ventilation alive.

RESULTS

Positive end-expiratory pressure, postoperative state (negatively), and Sequential Organ Failure Assessment score were independently associated with prolonged mechanical ventilation. The multinomial regression model yielded an accuracy (95% confidence interval) of 60% (53%-64%). The binary regression models yielded accuracies of 67% (61%-72%) and 69% (63%-75%) for the entire cohort and for survivors, respectively. The Cox regression model showed an equivalent to area under the curve of 0.67 (0.62-0.71).

CONCLUSIONS

Different predictive models of prolonged mechanical ventilation in general intensive care unit patients achieve a moderate level of overall accuracy, likely insufficient to assist in clinical decisions.

Diaries for recovery from critical illness

BACKGROUND

During intensive care unit (ICU) admission, patients experience extreme physical and psychological stressors, including the abnormal ICU environment. These experiences impact on a patient's recovery from critical illness and may result in both physical and psychological disorders. One strategy that has been developed and implemented by clinical staff to treat the psychological distress prevalent in ICU survivors is the use of patient diaries. These provide a background to the cause of the patient's ICU admission and an ongoing narrative outlining day-to-day activities.

OBJECTIVES

To assess the effect of a diary versus no diary on patients, and their caregivers or families, during the patient's recovery from admission to an ICU.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL; 2014, Issue 1), Ovid MEDLINE (1950 to January 2014), EBSCOhost CINAHL (1982 to January 2014), Ovid EMBASE (1980 to January 2014), PsycINFO (1950 to January 2014), Published International Literature on Traumatic Stress (PILOTS) database (1971 to January 2014); Web of Science Conference Proceedings Citation Index - Science and Social Science and Humanities (1990 to January 2014); seven clinical trial registries and reference lists of identified trials. We applied no language restriction.

SELECTION CRITERIA

We included randomized controlled trials (RCTs) or clinical controlled trials (CCTs) that evaluated the effectiveness of patient diaries, when compared to no ICU diary, for patients or family members to promote recovery after admission to ICU. Outcome measures for describing recovery from ICU included the risk of post-traumatic stress disorder (PTSD), anxiety, depression and post-traumatic stress symptomatology, health-related quality of life and costs.

DATA COLLECTION AND ANALYSIS

We used standard methodological approaches as expected by The Cochrane Collaboration. Two review authors independently reviewed titles for inclusion, extracted data and undertook risk of bias according to prespecified criteria.

MAIN RESULTS

We identified three eligible studies; two describing ICU patients (N = 358), and one describing relatives of ICU patients (N = 30). The study involving relatives of ICU patients was a substudy of family members from one of the ICU patient studies. There was a mixed risk of bias within the included studies. Blinding of participants to allocation was not possible and blinding of the outcome assessment was not adequately achieved or reported. Overall the quality of the evidence was low to very low. The patient diary intervention was not identical between studies. However, each provided a prospectively prepared, day-to-day description of the participants' ICU admission.No study adequately reported on risk of PTSD as described using a clinical interview, family or caregiver anxiety or depression, health-related quality of life or costs. Within a single study there was no clear evidence of a difference in risk for developing anxiety (risk ratio (RR) 0.29, 95% confidence interval (CI) 0.07 to 1.19) or depression (RR 0.38, 95% CI 0.12 to 1.19) in participants who received ICU diaries, in comparison to those that did not receive a patient diary. However, the results were imprecise and consistent with benefit in either group, or no difference. Within a single study there was no evidence of difference in median post-traumatic stress symptomatology scores (diaries 24, SD 11.6; no diary 24, SD 11.6) and delusional ICU memory recall (RR 1.04, 95% CI 0.84 to 1.28) between the patients recovering from ICU admission who received patient diaries, and those who did not. One study reported reduced post-traumatic stress symptomatology in family members of patients recovering from admission to ICU who received patient diaries (median 19; range 14 to 28), in comparison to no diary (median 28; range 14 to 38).

AUTHORS' CONCLUSIONS

Currently there is minimal evidence from RCTs of the benefits or harms of patient diaries for patients and their caregivers or family members. A small study has described their potential to reduce post-traumatic stress symptomatology in family members. However, there is currently inadequate evidence to support their effectiveness in improving psychological recovery after critical illness for patients and their family members.

Preventing ARDS: progress, promise, and pitfalls

Advances in critical care practice have led to a substantial decline in the incidence of ARDS over the past several years. Low tidal volume ventilation, timely resuscitation and antimicrobial administration, restrictive transfusion practices, and primary prevention of aspiration and nosocomial pneumonia have likely contributed to this reduction. Despite decades of research, there is no proven pharmacologic treatment of ARDS, and mortality from ARDS remains high. Consequently, recent initiatives have broadened the scope of lung injury research to include targeted prevention of ARDS. Prediction scores have been developed to identify patients at risk for ARDS, and clinical trials testing aspirin and inhaled budesonide/formoterol for ARDS prevention are ongoing. Future trials aimed at preventing ARDS face several key challenges. ARDS has not been validated as an end point for pivotal clinical trials, and caution is needed when testing toxic therapies that may prevent ARDS yet potentially increase mortality.

Clinical trial design in prevention and treatment of acute respiratory distress syndrome

Our ability to define appropriate molecular targets for preclinical development and develop better methods needs to be improved, to determine the clinical value of novel acute respiratory distress syndrome (ARDS) agents. Clinical trials must have realistic sample sizes and meaningful end points and use the available observation and meta-analytical data to inform design. Biomarker-driven studies or defined ARDS subsets should be considered to categorize specific at-risk populations most likely to benefit from a new treatment. Innovations in clinical trial design should be pursued to improve the outlook for future interventional trials in ARDS.

Survey of new 2007 and 2011 Cochrane reviews found 37% of prespecified outcomes not reported

OBJECTIVES

To survey the outcomes used in Cochrane Reviews, as part of our work within the Core Outcome Measures in Effectiveness Trials Initiative.

STUDY DESIGN AND SETTING

A descriptive survey of Cochrane Reviews, divided by Cochrane Review Group (CRG), published in full for the first time in 2007 and 2011. Outcomes specified in the methods section of each review and outcomes reported in the results section of each review were of interest, in this exploration of the common use of outcomes and core outcome sets (COS).

RESULTS

Seven hundred eighty-eight reviews, specifying 6,127 outcomes, were included. When we excluded specified outcomes from the 86 reviews that did not include any studies, we found that 1,996 (37%) specified outcomes were not reported. Of the 361 new reviews with studies from 2011, 113 (31%) had a "summary of findings" table (SoF). Fifteen broad outcome categories were identified and used to manage the outcome data. We found consistency in the use of these categories across CRGs but inconsistency in outcomes within these categories.

CONCLUSION

COS have been used rarely in Cochrane Reviews, but the introduction of SoF makes the development and application of COS timelier than ever.

Protocolized versus non-protocolized weaning for reducing the duration of mechanical ventilation in critically ill adult patients

BACKGROUND

This is an update of a review last published in Issue 5, 2010, of The Cochrane Library. Reducing weaning time is desirable in minimizing potential complications from mechanical ventilation. Standardized weaning protocols are purported to reduce time spent on mechanical ventilation. However, evidence supporting their use in clinical practice is inconsistent.

OBJECTIVES

The first objective of this review was to compare the total duration of mechanical ventilation of critically ill adults who were weaned using protocols versus usual (non-protocolized) practice.The second objective was to ascertain differences between protocolized and non-protocolized weaning in outcomes measuring weaning duration, harm (adverse events) and resource use (intensive care unit (ICU) and hospital length of stay, cost).The third objective was to explore, using subgroup analyses, variations in outcomes by type of ICU, type of protocol and approach to delivering the protocol (professional-led or computer-driven).

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library Issue 1, 2014), MEDLINE (1950 to January 2014), EMBASE (1988 to January 2014), CINAHL (1937 to January 2014), LILACS (1982 to January 2014),  ISI Web of Science and ISI Conference Proceedings (1970 to February 2014), and reference lists of articles. We did not apply language restrictions. The original search was performed in January 2010 and updated in January 2014.

SELECTION CRITERIA

We included randomized controlled trials (RCTs) and quasi-RCTs of protocolized weaning versus non-protocolized weaning from mechanical ventilation in critically ill adults.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed trial quality and extracted data. We performed a priori subgroup and sensitivity analyses. We contacted study authors for additional information.

MAIN RESULTS

We included 17 trials (with 2434 patients) in this updated review. The original review included 11 trials. The total geometric mean duration of mechanical ventilation in the protocolized weaning group was on average reduced by 26% compared with the usual care group (N = 14 trials, 95% confidence interval (CI) 13% to 37%, P = 0.0002). Reductions were most likely to occur in medical, surgical and mixed ICUs, but not in neurosurgical ICUs. Weaning duration was reduced by 70% (N = 8 trials, 95% CI 27% to 88%, P = 0.009); and ICU length of stay by 11% (N = 9 trials, 95% CI 3% to 19%, P = 0.01). There was significant heterogeneity among studies for total duration of mechanical ventilation (I(2) = 67%, P < 0.0001) and weaning duration (I(2) = 97%, P < 0.00001), which could not be explained by subgroup analyses based on type of unit or type of approach.

AUTHORS' CONCLUSIONS

There is evidence of reduced duration of mechanical ventilation, weaning duration and ICU length of stay with use of standardized weaning protocols. Reductions are most likely to occur in medical, surgical and mixed ICUs, but not in neurosurgical ICUs. However, significant heterogeneity among studies indicates caution in generalizing results. Some study authors suggest that organizational context may influence outcomes, however these factors were not considered in all included studies and could not be evaluated. Future trials should consider an evaluation of the process of intervention delivery to distinguish between intervention and implementation effects. There is an important need for further development and research in the neurosurgical population.

Outcomes and statistical power in adult critical care randomized trials

RATIONALE

Intensive care unit (ICU)-based randomized clinical trials (RCTs) among adult critically ill patients commonly fail to detect treatment benefits.

OBJECTIVES

Appraise the rates of success, outcomes used, statistical power, and design characteristics of published trials.

METHODS

One hundred forty-six ICU-based RCTs of diagnostic, therapeutic, or process/systems interventions published from January 2007 to May 2013 in 16 high-impact general or critical care journals were studied.

MEASUREMENT AND MAIN RESULTS

Of 146 RCTs, 54 (37%) were positive (i.e., the a priori hypothesis was found to be statistically significant). The most common primary outcomes were mortality (n = 40 trials), infection-related outcomes (n = 33), and ventilation-related outcomes (n = 30), with positive results found in 10, 58, and 43%, respectively. Statistical power was discussed in 135 RCTs (92%); 92 cited a rationale for their power parameters. Twenty trials failed to achieve at least 95% of their reported target sample size, including 11 that were stopped early due to insufficient accrual/logistical issues. Of 34 superiority RCTs comparing mortality between treatment arms, 13 (38%) accrued a sample size large enough to find an absolute mortality reduction of 10% or less. In 22 of these trials the observed control-arm mortality rate differed from the predicted rate by at least 7.5%.

CONCLUSIONS

ICU-based RCTs are commonly negative and powered to identify what appear to be unrealistic treatment effects, particularly when using mortality as the primary outcome. Additional concerns include a lack of standardized methods for assessing common outcomes, unclear justifications for statistical power calculations, insufficient patient accrual, and incorrect predictions of baseline event rates.

When the value of gold is zero

This manuscript presents the concerns around the increasingly common problem of not having readily available or useful “gold standard” measurements. This issue is particularly important in critical care where many measurements used in decision making are surrogates of what we would truly wish to use. However, the question is broad, important and applicable in many other areas.

In particular, a gold standard measurement often exists, but is not clinically (or ethically in some cases) feasible. The question is how does one even begin to develop new measurements or surrogates if one has no gold standard to compare with?

We raise this issue concisely with a specific example from mechanical ventilation, a core bread and butter therapy in critical care that is also a leading cause of length of stay and cost of care. Our proposed solution centers around a hierarchical validation approach that we believe would ameliorate ethics issues around radiation exposure that make current gold standard measures clinically infeasible, and thus provide a pathway to create a (new) gold standard.