Clinical trials comparing norepinephrine with vasopressin in patients with septic shock: a meta-analysis

Background: The effect of norepinephrine in patients with septic shock remains controversial. We conducted a meta-analysis to compare the mortality rates and benefits of norepinephrine and vasopressin. Methods: PubMed, EMBASE, and the Cochrane Library database were searched from database inception to December 2013. We selected randomized controlled trials in adults with septic shock and compared norepinephrine with vasopressin. After assessing the heterogeneity of treatment effects across trials using the I2 statistic, we used a fixed effects model (P >= 0.1) and expressed the results as risk ratios (RRs) for dichotomous outcomes or as standardized mean differences (SMDs) for continuous data with 95% confidence intervals (CIs). Meta-analysis was conducted using Review Manager 5.1 software. Results: Seven trials (n = 2323) met the inclusion criteria. Overall, the mortality rate in these seven trials was 36.2% (840/ 2323). There was no difference in mortality following the use of norepinephrine or vasopressin (RR 1.07; 95% CI 0.97-1.20; P = 0.19). Compared to norepinephrine, vasopressin had no significant effect on heart rate (HR) (SMD 0.21; 95% CI -0.08-0.50; P = 0.15), mean arterial pressure (MAP) (SMD 0.15; 95% CI -0.15-0.44; P = 0.33), cardiac index (CI) (SMD -0.10; 95% CI -0.64-0.44; P = 0.73), systemic vascular resistance index (SVRI) (SMD 0.15; 95% CI -0.39-0.70; P = 0.58), oxygen delivery (DO2) (SMD -0.06; 95% CI -0.62-0.49; P = 0.82), oxygen consumption (VO2) (SMD 0.03; 95% CI -0.52-0.59; P = 0.91) or lactic acid (SMD 0.07; 95% CI -0.23-0.36; P = 0.66). No significant heterogeneity was found in these comparisons (P >= 0.1). Conclusions: There is not sufficient evidence to prove conclusively that norepinephrine is superior to vasopressin in terms of mortality and hemodynamics. The effects of norepinephrine and vasopressin on patients with septic shock require further study in large randomized controlled trials.