Implications of Plasma Renin Activity and Plasma Aldosterone Concentration in Critically Ill Patients with Septic Shock

Background The renin-angiotensin-aldosterone system is closely associated with volume status and vascular tone in septic shock. The present study aimed to assess whether plasma renin activity (PRA) and plasma aldosterone concentration (PAC) measurements compared with conventional severity indicators are associated with mortality in patients with septic shock. Methods We evaluated 105 patients who were admitted for septic shock. Plasma levels of the biomarkers PRA and PAC, the PAC/PRA ratio, C-reactive protein (CRP) level, and cortisol level on days 1, 3, and 7 were serially measured. During the intensive care unit stay, relevant clinical information and laboratory results were recorded. Results Patients were divided into two groups according to 28-day mortality: survivors (n = 59) and non-survivors (n = 46). The survivor group showed lower PRA, PAC, Acute Physiologic and Chronic Health Evaluation (APACHE) II score, and Sequential Organ Failure Assessment (SOFA) score than did the non-survivor group (all P < 0.05). The SOFA score was positively correlated with PRA (r = 0.373, P < 0.001) and PAC (r = 0.316, P = 0.001). According to receiver operating characteristic analysis, the areas under the curve of PRA and PAC to predict 28-day mortality were 0.69 (95% confidence interval [CI], 0.58 to 0.79; P = 0.001) and 0.67 (95% CI, 0.56 to 0.77; P = 0.003), respectively, similar to the APACHE II scores and SOFA scores. In particular, the group with PRA value ≥3.5 ng ml-1 h-1 on day 1 showed significantly greater mortality than did the group with PRA value <3.5 ng ml-1 h-1 (log-rank test, P < 0.001). According to multivariate analysis, SOFA score (hazard ratio, 1.11; 95% CI, 1.01 to 1.22), PRA value ≥3.5 ng ml-1 h-1 (hazard ratio, 3.25; 95% CI, 1.60 to 6.60), previous history of cancer (hazard ratio, 3.44; 95% CI, 1.72 to 6.90), and coronary arterial occlusive disease (hazard ratio, 2.99; 95% CI, 1.26 to 7.08) were predictors of 28-day mortality. Conclusions Elevated PRA is a useful biomarker to stratify the risk of critically ill patients with septic shock and is a prognostic predictor of 28-day mortality.