We included six RCTs (n = 833) from previously published meta-analyses [4, 10] addressing the topic [3, 18,19,20,21,22]. The updated search found 759 new citations, from which we included 12 additional RCTs (n = 1993) [7, 23,24,25,26,27,28,29] (e-Fig. 1) for a total of 18 RCTs (n = 2826) that met eligibility criteria. A recent meta-analysis published in JAMA [4] included seven RCTs examining the role of corticosteroids in patients with COVID-19. As not all of these patients were mechanically ventilated or had ARDS, we used data only from the subgroup of patients that received invasive mechanical ventilation (eFigure 1 from the JAMA report) or when not available, contacted individual trial authors for these subgroup results.
Table 1 shows characteristics of all included RCTs which randomized between 11 and 1007 patients. Five studies were conducted in the USA [18, 21, 23, 30], four in China [7, 22, 25, 26], two in Spain [3, 7], two in France [24], two in the UK [29], two in Brazil [27, 28], and one each in Denmark [7], Kuwait [20], Thailand [19], Australia [30], Canada [30], Ireland [30], the Netherlands [30], and New Zealand [30]. All patients included in the review were invasively ventilated, 12 of the RCTs included 1403 patients with AECC or Berlin-criteria ARDS [3, 7, 18,19,20,21,22,23,24,25,26,27], and 6 included 1423 patients with COVID-19 [7, 28, 29]. Additionally, while most non COVID-19 studies provided a breakdown of ARDS etiologies in their demographics, they did not provide outcome-based subgroup data based on specific aetiologies. Six trials used hydrocortisone [7, 19, 22, 24], eight used methylprednisolone [18, 20, 21, 23, 25, 26, 28], and four used dexamethasone [3, 7, 27, 29]. Two of the RCTs [21, 23] initiated corticosteroids late in the course of ARDS (defined as 1 week after diagnosis), whereas the other 16 RCTs initiated corticosteroids within the first week of diagnosis. Eight of the trials provided 7 days or less of corticosteroid therapy [7, 19, 22, 24,25,26, 28], while the rest provided 10 days or more. The median dose of corticosteroid used was 88 mg of methylprednisolone (equivalent to 400 mg of hydrocortisone) per day and seven of the included trials used a dose less than this [7, 19, 22, 24,25,26, 28, 29], while the other 11 used a dose higher than 88 mg. The lowest daily dose used was 30 mg of methylprednisolone [28, 29] while the highest was 120 mg of methylprednisolone [21, 23, 25, 26]. 10 RCTs administered a placebo to their control group [7, 18,19,20,21,22,23,24, 28] while the remainder only provided standard care.
Table 1 Characteristics of included studies We judged three RCTs to be at high ROB, one due to concerns regarding randomization and selection of the reported results [20] and another two due to incomplete reporting regarding randomization, descriptions of interventions, and selection of the reported results [25, 26]. The remainder of the trials were judged either at low ROB or some concern. e-Table 2 summarizes the ROB for each individual trial for the outcome of mortality. Table 2 and e-Table 3 depict the pooled outcomes with associated GRADE certainty of evidence.
Table 2 Summary of findings table Corticosteroids probably reduce 28-day mortality in patients with ARDS (2740 patients in 16 trials, RR 0.82, 95% CI 0.72–0.95, random effects model, absolute risk reduction (ARR) 8.0%, 95% CI 2.2–12.5% reduction, number needed to treat (NNT) 12.5, 95% CI 8.0–45.5, moderate certainty, Fig. 1). Both the initial TSA and posthoc TSA were consistent in that they showed that the optimal information size was not reached (n = 4690, 80% power; n = 6275, 90% power, Supplementary Materials).We rated this outcome down once due to a combination of borderline indirectness as eight of the studies included mechanically ventilated patients with COVID-19 respiratory failure, which were not explicitly defined as ARDS, and for borderline imprecision as although the 95% confidence interval only included benefit with corticosteroids, the optimal information size based on TSA was not met. When including trials that only enrolled patients meeting formal AECC/Berlin ARDS criteria, this conclusion and certainty of evidence did not change (1317 patients in 10 trials, RR 0.77, 95% CI 0.63–0.94, ARR 10.7%, 95% CI 2.8–17.3% reduction, NNT 9.3, 95% CI 5.8–35.7, moderate certainty, Fig. 2). Subgroup analysis based on COVID-19 status (Fig. 1), steroid type (e-Fig. 2), steroid initiation time (e-Fig. 3), steroid dosage (e-Fig. 4), and ROB (e-Fig. 5) did not demonstrate any credible subgroup effects. Meta-regression based on dosage of steroid as a continuous variable also showed no subgroup effect (p = 0.41, e-Fig. 6). Patients who received a longer course of corticosteroids (over 7 days) had higher rates of survival than those who received a shorter course (7 days or less) (p-value for subgroup interaction = 0.04, moderate credibility) (Fig. 3). We performed sensitivity analyses excluding the five studies that reported a mortality endpoint other than at 28 days [3, 20, 21, 23, 30] (e-Fig. 7), and the two studies that initiated corticosteroids late [21, 23] (e-Fig. 17), none of which substantially altered the pooled estimates or conclusions. None of our post-hoc subgroup analyses showed credible subgroup effects (e-Figs. 15, 16, 19).
Corticosteroid use may reduce ICU mortality (RR 0.61, 95% CI 0.38–0.99, ARR 18.6%, 95% CI 0.5–29.6% reduction, low certainty, e-Fig. 8) and probably reduce hospital mortality (RR 0.67, 95% CI 0.46–0.96, ARR 16.6%, 2.0–27.2% reduction, moderate certainty, e-Fig. 9) in critically ill patients with ARDS. The use of corticosteroids may lead to fewer days of mechanical ventilation (MD 4.04 days fewer, 95% CI 2.53–5.53 days fewer, low certainty, e-Fig. 18) and a shorter hospital length of stay (MD 8.05 days fewer, 95% CI 3.12–12.98 days fewer, low certainty, e-Fig. 10). There was an uncertain effect on ICU length of stay with corticosteroids (MD 0.78 days more, 95% CI 4.11 days more to 5.68 days fewer, very low certainty, e-Fig. 11).
There are unclear differences in rates of neuromuscular weakness (271 patients in 2 trials, RR 0.85, 95% CI 0.62–1.18, e-Fig. 12) and gastrointestinal bleeding (436 patients in 5 trials, RR 1.20, 95% CI 0.43–3.34, e-Fig. 13) with corticosteroids although these were all based on low or very low certainty evidence. There was probably an increase in hyperglycemia (915 patients in six trials, RR 1.11, 95% CI 1.01–1.23, moderate certainty evidence, e-Fig. 14) with corticosteroids; however, this outcome was rated down for indirectness, given the variability in definitions of hyperglycemia used across studies. Superinfections due to corticosteroid use are summarized as in e-Table 4. Since some studies individually counted multiple infections in one individual as separate data points and others did not, we opted not to pool this data. Although we could not pool data for this outcome, and understanding these limitations, it did not appear as though there was any signal for increase in superinfection (221 infections in corticosteroid group, 244 infections in control group).