Sixteen RCTs (n=523) were included.
Thirteen RCTs reported adequate allocation concealment. Twelve RCTs were double-blinded.
Surfactant (3 RCTs, n=79): the studies showed that, compared with the control, surfactant had no significant effect on days of ventilation (WMD -2.58 days, 95% CI: -5.34, 0.18, P=0.07) but significantly decreased ICU days (WMD -3.3 days, 95% CI: -6.38, -0.23, P=0.04). Statistically significant heterogeneity was found for both meta-analyses (P<0.00001). One RCT found decreases in days ventilated and ICU days that were much more than in the other two RCTs.
Systemic corticosteroids: the studies used different doses and durations of treatment. There was no statistically significant difference between systemic corticosteroids and control for days of ventilation (3 RCTs, n=137; WMD 0.62 days, 95% CI: -2.78, 1.53, P=0.57). Similarly, there was no significant difference for duration of hospital stay (2 RCTs, n=96; WMD -2.44 days, 95% CI: -9.30, 4.42, P=0.5). Significant between- study heterogeneity was found in the second analysis.
Ribavirin (one meta-analysis of 3 RCTs, n=104): the meta-analysis found that, compared with the control, ribavirin significantly reduced days of ventilation (WMD 1.2 days, 95% CI: -3.4, -0.2, P=0.03) and non-statistically significantly reduced hospital stay (WMD -1.9 days, 95% CI: -4.6, 0.9, P=0.20). There was no significant difference between treatments in mortality (relative risk 0.36, 95% CI: 0.07, 1.77, P=0.21). No significant heterogeneity was found for any of these meta-analyses.
Immune globulin (3 RCTs, n=35; 33 and 25 ventilated): the studies used different interventions. None of the studies found any statistically significant difference between immune globulin and the control for days ventilated or hospital stay.
Helium (1 RCT, n=13): the RCT provided no data on the effects of heliox on ICU stay.
There was no statistically significant difference in ICU days or ventilator days between control and vitamin A (1 RCT, n=9 in ICU), erythropoietin (1 RCT, n=44) or interferon (1 RCT, n=6 ventilated).