Perspective on optimizing clinical trials in critical care: how to puzzle out recurrent failures

Does Early Vasopressin in Septic Shock Improve Outcomes? An Important Piece to This Emerging Puzzle Has Arrived

In this month's Annals of Pharmacotherapy, the largest observational study assessing the early versus later use of vasopressin has been published. When this new study is combined with the other available observational studies, there are 2 important outcomes to focus on. When all the observational studies are pooled together, no reduction in new onset arrhythmias is seen (odds ratio [OR] = 0.91, 95% confidence interval [CI] = 0.41-1.95) with early versus late vasopressin use while the reduction in renal replacement therapy just missed statistical significance (OR = 0.56, 95% CI = 0.32-1.00). Early vasopressin likely does not reduce new onset arrhythmias versus later use but might reduce the need for renal replacement therapy.

Evaluation of a closed loop-blood sampling system in intensive care: A pilot randomised controlled trial. The ENCLOSE trial

OBJECTIVE

To test the feasibility of conducting a randomised controlled trial to evaluate the impact of a closed-loop blood sampling system and blood conservation bundle.

METHODS

Single site, parallel group, pilot randomised control trial comparing open system sampling to closed system sampling and conservation bundle aligned with national guidelines. Randomisation sequence was generated by an independent statistician and allocation concealment maintained via sealed opaque envelopes. The study setting was the general intensive care unit of a major metropolitan public hospital in Queensland, Australia. Participants were ≥ 18 years who had an arterial catheter inserted in intensive care. Main outcome measures included trial feasibility, blood sample loss, haematocrit (HCT) change, and packed red blood cell transfusion use.

RESULTS

Eighty patients were randomised (n = 39 open group, n = 41 closed group). Characteristics in each group were equal at baseline with overall median age 60 years (IQR 48.6-70.4), 58 % male, and median APACHE II score 16 (IQR 11-22). The proportion of patients eligible was 29 % and missed eligible was 65 %. Otherwise, feasibility criteria were met with proportion of eligible patients agreeing to enrolment 99 %, 100 % of patients receiving allocated treatment; only 1 % of data missing. Analysis demonstrated a significant reduction in mean daily blood sample losses (open 32.7 (SD 1.58) mL vs closed 15.5 (SD 5.79) mL, t = -8.454, df = 78, p < 0.001).

CONCLUSIONS

A large, multi-site trial is feasible with enhanced eligibility criteria, increased recruitment support. The intervention reduced daily blood sample volumes and transfusion use. Further trials are required to provide both effectiveness and implementation outcomes.

Recruitment characteristics of randomised trials in critical care: A systematic review

BACKGROUND/AIMS

To summarise the temporal trends of recruitment and methodological characteristics of critical care randomised controlled trials with the primary outcome of mortality.

METHODS

PubMed was searched for articles meeting inclusion and exclusion criteria. Randomised controlled trials, with primary outcome of mortality, of adult and paediatric critical care patients treated in an intensive care unit, were included. Neonatal intensive care unit trials, non-English publications and conference proceedings or abstracts without full-length publications were excluded. Duplicate literature search, article selection and quality assessment were performed by two reviewers with disputes resolved through discussion. Data were extracted into a custom-designed Research Electronic Data Capture database.

RESULTS

The search identified 67,199 records of which 230 were included. The annual number of critical care randomised controlled trials published increased gradually over a 30-year period from 0 in 1990 to 19 in 2014 with stabilisation at 8-11 between 2015 and 2020. Twenty-seven percent of randomised controlled trials were low risk in all categories using the Cochrane Risk of Bias tool. Methodological characteristics such as registration on clinical trials registries and data safety monitoring committee presence significantly (p < 0.001) increased over time. The median recruitment was 376 patients (interquartile range 125-895) with significant increase (p = 0.002) from 62 (interquartile range: 33-486) in 1991 to 725 (interquartile range: 537-2600) in 2020. This was accompanied by an increase in recruitment times. Thus overall, recruitment rates did not increase. Early cessation occurred in 23% (54/230) of randomised controlled trials with no temporal trend.

CONCLUSION

The number, size and some methodological qualities of critical randomised controlled trials with primary outcome of mortality have increased over time, but rates of recruitment and early cessation have been unchanged.

Research Needs for Inpatient Management of Severe Alcohol Withdrawal Syndrome: An Official American Thoracic Society Research Statement

Background: Severe alcohol withdrawal syndrome (SAWS) is highly morbid, costly, and common among hospitalized patients, yet minimal evidence exists to guide inpatient management. Research needs in this field are broad, spanning the translational science spectrum. Goals: This research statement aims to describe what is known about SAWS, identify knowledge gaps, and offer recommendations for research in each domain of the Institute of Medicine T0-T4 continuum to advance the care of hospitalized patients who experience SAWS. Methods: Clinicians and researchers with unique and complementary expertise in basic, clinical, and implementation research related to unhealthy alcohol consumption and alcohol withdrawal were invited to participate in a workshop at the American Thoracic Society 2019 International Conference. The committee was subdivided into four groups on the basis of interest and expertise: T0-T1 (basic science research with translation to humans), T2 (research translating to patients), T3 (research translating to clinical practice), and T4 (research translating to communities). A medical librarian conducted a pragmatic literature search to facilitate this work, and committee members reviewed and supplemented the resulting evidence, identifying key knowledge gaps. Results: The committee identified several investigative opportunities to advance the care of patients with SAWS in each domain of the translational science spectrum. Major themes included 1) the need to investigate non-γ-aminobutyric acid pathways for alcohol withdrawal syndrome treatment; 2) harnessing retrospective and electronic health record data to identify risk factors and create objective severity scoring systems, particularly for acutely ill patients with SAWS; 3) the need for more robust comparative-effectiveness data to identify optimal SAWS treatment strategies; and 4) recommendations to accelerate implementation of effective treatments into practice. Conclusions: The dearth of evidence supporting management decisions for hospitalized patients with SAWS, many of whom require critical care, represents both a call to action and an opportunity for the American Thoracic Society and larger scientific communities to improve care for a vulnerable patient population. This report highlights basic, clinical, and implementation research that diverse experts agree will have the greatest impact on improving care for hospitalized patients with SAWS.

Heparin - Messias or Verschlimmbesserung?

A heightened risk of thrombosis noted early on with the severe acute respiratory syndrome coronavirus 2 infection led to the widespread use of heparin anticoagulation in the coronavirus disease 2019 (COVID-19) pandemic. However, reports soon started appearing in the literature where an apparent failure of heparin to prevent thrombotic events was observed in hospitalized patients with this viral infection. In this review, we explore the likely mechanisms for heparin failure with particular relevance to COVID-19. We also explore the role of anti-Xa assays and global hemostatic tests in this context. The current controversy of dosing heparin in this disease is detailed with some possible mechanistic reasons for anticoagulant failure. We hope that lessons learnt from the use of heparin in COVID-19 could assist us in the appropriate use of this anticoagulant in the future.

Utilizing machine learning to improve clinical trial design for acute respiratory distress syndrome

Heterogeneous patient populations, complex pharmacology and low recruitment rates in the Intensive Care Unit (ICU) have led to the failure of many clinical trials. Recently, machine learning (ML) emerged as a new technology to process and identify big data relationships, enabling a new era in clinical trial design. In this study, we designed a ML model for predictively stratifying acute respiratory distress syndrome (ARDS) patients, ultimately reducing the required number of patients by increasing statistical power through cohort homogeneity. From the Philips eICU Research Institute (eRI) database, no less than 51,555 ARDS patients were extracted. We defined three subpopulations by outcome: (1) rapid death, (2) spontaneous recovery, and (3) long-stay patients. A retrospective univariate analysis identified highly predictive variables for each outcome. All 220 variables were used to determine the most accurate and generalizable model to predict long-stay patients. Multiclass gradient boosting was identified as the best-performing ML model. Whereas alterations in pH, bicarbonate or lactate proved to be strong predictors for rapid death in the univariate analysis, only the multivariate ML model was able to reliably differentiate the disease course of the long-stay outcome population (AUC of 0.77). We demonstrate the feasibility of prospective patient stratification using ML algorithms in the by far largest ARDS cohort reported to date. Our algorithm can identify patients with sufficiently long ARDS episodes to allow time for patients to respond to therapy, increasing statistical power. Further, early enrollment alerts may increase recruitment rate.

Interrater Reliability of Muscle Ultrasonography Image Acquisition by Physical Therapists in Patients Who Have or Who Survived Critical Illness

OBJECTIVE

Previous studies have demonstrated that muscle ultrasound (US) can be reliably performed at the patient bedside by novice assessors with minimal training. The primary objective of this study was to determine the interrater reliability of muscle US image acquisition by physical therapists and physical therapist students. Secondarily, this study was designed to elucidate the process for training physical therapists to perform peripheral skeletal muscle US.

METHODS

This was a cross-sectional observational study. Four novices and 1 expert participated in the study. Novice sonographers engaged in a structured training program prior to implementation. US images were obtained on the biceps brachii, quadriceps femoris, and tibialis anterior muscles in 3 groups: patients in the intensive care unit, patients on the hospital ward, and participants in the outpatient gym who were healthy. Reliability of image acquisition was analyzed compared with the expert sonographer.

RESULTS

Intraclass correlation coefficient values ranged from 0.76 to 0.97 with an average for all raters and all muscles of 0.903, indicating excellent reliability of image acquisition. In general, the experienced physical therapist had higher or similar intraclass correlation coefficient values compared with the physical therapist students in relation to the expert sonographer.

CONCLUSIONS

Excellent interrater reliability for US was observed regardless of the level of experience, severity of patient illness, or patient setting. These findings indicate that the use of muscle US by physical therapists can accurately capture reliable images in patients with a range of illness severity and different clinical practice settings across the continuum of care.

IMPACT

Physical therapists can utilize US to obtain images to assess muscle morphology.

LAY SUMMARY

Physical therapists can use noninvasive US as an imaging tool to assess the size and quality of peripheral skeletal muscle. This study demonstrates that physical therapists can receive training to reliably obtain muscle images in patients admitted to the intensive care unit who may be at risk for muscle wasting and may benefit from early rehabilitation.

Optimisation of the organ donor and effects on transplanted organs: a narrative review on current practice and future directions

Mortality remains high for patients on the waiting list for organ transplantation. A marked imbalance between the number of available organs and recipients that need to be transplanted persists. Organs from deceased donors are often declined due to perceived and actual suboptimal quality. Adequate donor management offers an opportunity to reduce organ injury and maximise the number of organs than can be offered in order to respect the donor's altruistic gift. The cornerstones of management include: correction of hypovolaemia; maintenance of organ perfusion; prompt treatment of diabetes insipidus; corticosteroid therapy; and lung protective ventilation. The interventions used to deliver these goals are largely based on pathophysiological rationale or extrapolations from general critical care patients. There is currently insufficient high-quality evidence that has assessed whether any interventions in the donor after brain death may actually improve immediate post-transplant function and long-term graft survival or recipient survival after transplantation. Improvements in our understanding of the underlying mechanisms following brain death, in particular the role of immunological and metabolic changes in donors, offer promising future therapeutic opportunities to increase organ utilisation. Establishing a UK donor management research programme involves consideration of ethical, logistical and legal issues that will benefit transplanted patients while respecting the wishes of donors and their families.

Does asymmetry in patient recruitment in large critical care trials follow the Pareto principle?

BACKGROUND

Randomised controlled trials (RCT) may be hindered by slow recruitment rates, particularly in critically ill patients. While statistical models to predict recruitment rates have been described, no systematic assessment has been conducted of the distribution of recruitment across sites, temporal trends in site participation and impact of competing trials on patient recruitment.

METHODS

We used recruitment and screening logs from the SAFE, NICE-SUGAR, RENAL, CHEST and ADRENAL trials, five of the largest critical care RCTs. We quantified the extent of recruitment asymmetry between sites using Lorenz curves and Gini coefficients and assessed whether the recruitment distribution across sites follow the Pareto principle, which states that 80% of effects come from 20% of causes. Peak recruitment rates and growth in participating sites were calculated.

RESULTS

In total, 25,412 patients were randomised in 99 intensive care units (ICUs) for the five trials. Distribution of recruitment was asymmetric, with a small number of ICUs recruiting a large proportion of the patients. The Gini coefficients ranged from 0.14 to 0.52. The time to peak recruitment rate ranged from 7 to 41 months and was variable (7, 31, 41, 10 and 40 months). Over time, the proportion of recruitment at non-tertiary ICUs increased from 15% to 34%.

CONCLUSIONS

There is asymmetry of recruitment with a small proportion of ICUs recruiting a large proportion of patients. The distributions of recruitment were not consistent with the Pareto principle. There has been increasing participation of non-tertiary ICUs in clinical trials.