Figure 2a. Kaplan–Meier curves for persistence of posttraumatic stress disorder (PTSD): comparing age of PTSD onset cohorts.

Cohort 1: 1 to 12 years of age at onset (n = 108)

Cohort 2: 13 to 17 years of age at onset (n = 64)

Cohort 3: 18 to 30 years of age at onset (n = 226)

Cohort 4: ≥31 years of age at onset (n = 125)

Testing homogeneity of survival curves over strata: χ² = 38.07, df = 3, P < 0.001 (unweighted results)