Second, the estimated U.S.-based population prevalence of DSM-5 PTSD was statistically significantly lower than the estimated DSM-IV PTSD population prevalence under both the broadest lifetime Composite Event definition and the narrowest past–12 month Same Event PTSD definition. PTSD prevalence according to the DSM-5 criteria was lower than the PTSD prevalence according to the DSM-IV criteria under the other four definitions although not significantly so. Thus, the changes made in the DSM-5 did not result in increased PTSD prevalence counter to the Calhoun et al. (2012) prediction that prevalence according to the DSM-5 criteria would be substantially higher under conditions in which true population prevalence according to the DSM-IV criteria was comparable to that found in the present study.
