Background. Partial PTSD, employed initially in relation to Vietnam veterans, has been recently extended to civilian victims of trauma. We examined the extent to which partial PTSD is distinguishable from full DSM-PTSD with respect to level of impairment.

Method. A representative sample of 2181 persons was interviewed by telephone to record lifetime traumatic events and to assess DSM-IV PTSD criteria. Partial PTSD was defined as [ges ]1 symptom in each of three symptom groups (criteria B, C and D) and duration of [ges ]1 month. Impairment in persons with PTSD and partial PTSD was measured by number of work-related and personal disability days during the 30-day period when the respondent was most upset by the trauma.

Results. Compared to exposed persons with neither PTSD nor partial PTSD, increment in work-loss days associated with PTSD was 11·4 (S.E.=0·6) days and with partial PTSD, 3·3 (S.E.=0·4) days (adjusted for sex, education and employment). Similar disparities were found across other impairment indicators. Persons who fell short of PTSD criteria by one symptom of avoidance and numbing reported an increment of 5·0 (S.E.=0·7) work-loss days, 6·0 fewer than full PTSD. PTSD was associated with excess impairment, controlling for number of symptoms. A significantly lower proportion of persons with partial PTSD than full PTSD experienced symptoms for more than 2 years. A lower proportion of persons with partial PTSD than full PTSD had an etiologic event of high magnitude.

Conclusions. PTSD identifies the most severe trauma victims, who are markedly distinguishable from victims with subthreshold PTSD.