Efficacy of Progesterone for Acute Traumatic Brain Injury: a Meta-analysis of Randomized Controlled Trials

Progesterone, a steroid hormone, has been shown to have multifactorial neuroprotective effects in a variety of animal models of acute traumatic brain injury (TBI). Translation to humans showed positive effects in previous phase II trials, but unfortunately, negative results were observed in two recent phase III trials. The present study focuses on the efficacy of progesterone on acute TBI based on the published data of randomized controlled trials (RCTs). MEDLINE, EMBASE, and Cochrane Library were used to search from January 1980 to August 2015 for English language studies. The primary outcome was a favorable outcome in the Glasgow outcome scale (GOS). The secondary outcomes included mortality and adverse events. A total of 2396 patients from 5 RCTs were included in the present study. There were no significant differences in favorable outcome (relative risk (RR) 1.07, 95 % confidence interval (CI) 0.91 to 1.27, P = 0.41) and mortality rate (RR 0.85, 95 % CI 0.65 to 1.13, P = 0.27) between progesterone and placebo groups. In a subgroup analysis, favorable outcome (RR 1.45, 95 % CI 1.11 to 1.89, P = 0.007) and decreased mortality rate (RR 0.58, 95 % CI 0.41 to 0.84, P = 0.004) are only observed in the phase II RCTs. The included factors were the severity of TBI, method of drug administration, and duration of observation and had no influence on the observed outcomes. Sensitivity analysis showed that all the outcomes were stable after excluding Shakeri (Clin Neurol Neurosurg 115: 2019-2022, 2013) or Wright (N Engl J Med 371: 2457-2466, 2014) trials. The quality of the evidence was varied from high to low. In conclusion, progesterone has no significant improvement in the functional recovery and mortality rate after acute TBI.