Fig. 2. Kaplan–Meier curves for the occurrence of postdural puncture headache (PDPH) in cosyntropin group and control group. Hazard ratio = 0.32 (95% confidence interval = 0.16–0.55, P < 0.0001). Median time to occurrence of PDPH = 21.5 h in control group and is undefined in cosyntropin group. ADP = accidental dural puncture.