Survival curve for patients with more severe and less severe septic shock. Ninety-day Kaplan-Meier survival curves for patients with more severe and less severe septic shock in the Vasopressin and Septic Shock Trial comparing vasopressin-infused patients with norepinephrine-infused patients within each stratum. (a) Patients in the more severe stratum (P = 0.77 at day 28 and P = 0.92 at day 90). (b) Patients in the less severe stratum (P = 0.05 at day 28 and P = 0.03 at day 90). Solid black line, vasopressin-treated group; dotted line, norepinephrine-treated group; vertical line, day 28. P values were calculated using the log-rank statistic.