Causal Bayesian machine learning to assess treatment effect heterogeneity by dexamethasone dose for patients with COVID-19 and severe hypoxemia

Abstract The currently recommended dose of dexamethasone for patients with severe or critical COVID-19 is 6 mg per day (mg/d) regardless of patient features and variation. However, patients with severe or critical COVID-19 are heterogenous in many ways (e.g., age, weight, comorbidities, disease severity, and immune features). Thus, it is conceivable that a standardized dosing protocol may not be optimal. We assessed treatment effect heterogeneity in the COVID STEROID 2 trial, which compared 6 mg/d to 12 mg/d, using a causal inference framework with Bayesian Additive Regression Trees, a flexible modeling method that detects interactive effects and nonlinear relationships among multiple patient characteristics simultaneously. We found that 12 mg/d of dexamethasone, relative to 6 mg/d, was probably associated with better long-term outcomes (days alive without life support and mortality after 90 days) among the entire trial population (i.e., no signals of harm), and probably more beneficial among those without diabetes mellitus, that were older, were not using IL-6 inhibitors at baseline, weighed less, or had higher level respiratory support at baseline. This adds more evidence supporting the use of 12 mg/d in practice for most patients not receiving other immunosuppressants and that additional study of dosing could potentially optimize clinical outcomes

Heterogenous treatment effects of dexamethasone 12 mg vs. 6 mg in patients with COVID-19 and severe hypoxaemia - post hoc exploratory analyses of the COVID STEROID 2 trial.

BACKGROUND Corticosteroids improve outcomes in patients with severe COVID-19. In the COVID STEROID 2 randomised clinical trial, we found high probabilities of benefit with dexamethasone 12 mg vs. 6 mg daily. While no statistically significant heterogeneity in treatment effects (HTE) was found in the conventional, dichotomous subgroup analyses, these analyses have limitations, and HTE could still exist. METHODS We assessed whether HTE were present for days alive without life support and mortality at day 90 in the trial according to baseline age, weight, number of comorbidities, category of respiratory failure (type of respiratory support system and oxygen requirements), and predicted risk of mortality using an internal prediction model. We used flexible models for continuous variables and logistic regressions for categorical variables without dichotomisation of the baseline variables of interest. HTE was assessed both visually and with P- and S-values from likelihood ratio tests. RESULTS There was no strong evidence for substantial HTE on either outcome according to any of the baseline variables assessed with all P-values >0.37 (and all S-values <1.43) in the planned analyses and no convincingly strong visual indications of HTE. CONCLUSIONS We found no strong evidence for HTE with 12 vs. 6 mg dexamethasone daily on days alive without life support or mortality at day 90 in patients with COVID-19 and severe hypoxaemia, although these results cannot rule out HTE either. This article is protected by copyright. All rights reserved

Effects of 12 mg vs. 6 mg dexamethasone on thromboembolism and bleeding in patients with critical COVID-19-a post hoc analysis of the randomized, blinded COVID STEROID 2 trial

BackgroundThromboembolism is more common in patients with critical COVID-19 than in other critically ill patients, and inflammation has been proposed as a possible mechanism. The aim of this study was to investigate if 12 mg vs. 6 mg dexamethasone daily reduced the composite outcome of death or thromboembolism in patients with critical COVID-19.MethodsUsing additional data on thromboembolism and bleeding we did a post hoc analysis of Swedish and Danish intensive care unit patients enrolled in the blinded randomized COVID STEROID 2 trial comparing 12 mg vs. 6 mg dexamethasone daily for up to 10 days. The primary outcome was a composite outcome of death or thromboembolism during intensive care. Secondary outcomes were thromboembolism, major bleeding, and any bleeding during intensive care.ResultsWe included 357 patients. Whilst in intensive care, 53 patients (29%) in the 12 mg group and 53 patients (30%) in the 6 mg group met the primary outcome with an unadjusted absolute risk difference of - 0.5% (95% CI - 10 to 9.5%, p = 1.00) and an adjusted OR of 0.93 (CI 95% 0.58 to 1.49, p = 0.77). We found no firm evidence of differences in any of the secondary outcomes.ConclusionsAmong patients with critical COVID-19, 12 mg vs. 6 mg dexamethasone daily did not result in a statistically significant difference in the composite outcome of death or thromboembolism. However, uncertainty remains due to the limited number of patients

Corticosteroids in COVID-19 and non-COVID-19 ARDS: a systematic review and meta-analysis

International audiencePurpose: Corticosteroids are now recommended for patients with severe COVID-19 including those with COVID-related ARDS. This has generated renewed interest regarding whether corticosteroids should be used in non-COVID ARDS as well. The objective of this study was to summarize all RCTs examining the use of corticosteroids in ARDS. Methods: The protocol of this study was pre-registered on PROSPERO (CRD42020200659). We searched online databases including MEDLINE, EMBASE, CDC library of COVID research, CINAHL, and COCHRANE. We included RCTs that compared the effect of corticosteroids to placebo or usual care in adult patients with ARDS, including patients with COVID-19. Three reviewers abstracted data independently and in duplicate using a pre-specified standardized form. We assessed individual study risk of bias using the revised Cochrane ROB-2 tool and rated certainty in outcomes using GRADE methodology. We pooled data using a random effects model. The main outcome for this review was 28-day-mortality. Results: We included 18 RCTs enrolling 2826 patients. The use of corticosteroids probably reduced mortality in patients with ARDS of any etiology (2740 patients in 16 trials, RR 0.82, 95% CI 0.72–0.95, ARR 8.0%, 95% CI 2.2–12.5%, moderate certainty). Patients who received a longer course of corticosteroids (over 7 days) had higher rates of survival compared to a shorter course. Conclusion: The use of corticosteroids probably reduces mortality in patients with ARDS. This effect was consistent between patients with COVID-19 and non-COVID-19 ARDS, corticosteroid types, and dosage