Participants in the mindfulness-based stress reduction group demonstrated greater improvement in self-reported PTSD symptom severity during treatment ( change in mean PTSD Checklist scores from 63.6 to 55.7 vs 58.8 to 55.8 with present-centered group therapy ; between-group difference , 4.95 ; 95 % CI , 1.92-7 .99 ; P = .002 ) and at 2-month follow-up ( change in mean scores from 63.6 to 54.4 vs 58.8 to 56.0 , respectively ; difference , 6.44 ; 95 % CI , 3.34-9 .53 , P < .001 ) .