What do we know about trauma types in PTSD clinical trials?

Determining trauma type classifications for RCTs in the PTSD Repository is complicated because assessment of trauma history varies greatly across studies. In some cases, trauma assessment is limited to whether participants have experienced a specific trauma type of interest for a study, for example sexual assault or military trauma. In other cases, assessment includes obtaining information on all the types of traumas study participants experienced. Some studies look even further into the number of times a trauma type is experienced--or number of all cumulative traumas or types of traumas experienced across a lifetime--as well.

Knowing information about the type(s) or number of traumas experienced by participants in treatment trials is valuable for at least 2 reasons. First, the type of trauma is important because we want to know if specific traumatic events are associated with different treatment outcomes. Early on researchers wanted to know if specific treatments worked better for particular trauma types. To date, data show that the most effective treatments work for all types of trauma.

Second, knowing the number of traumas experienced (or the number of different types of traumas experienced) provides information about the PTSD severity of the sample being studied. Experiencing multiple traumas is associated with increased PTSD symptom severity. Amount of traumatic exposure can affect whether findings are generalizable (applicable) in terms of treatment efficacy.

In the PTSD Repository, most studies (82%) report some information about trauma exposure history. Assessing for trauma is part of the PTSD diagnostic practice; however, research participants may be included based upon self-report or review of medical charts (which may not include information about specific types of trauma(s) experienced).

In most studies with trauma history information, participants report a variety of traumatic experiences; and, the number of trauma types reported by participants in RCTs that collect such information (n=33 RCTs) range from 1 to almost 15. Among studies (n=52 RCTs) that count number of traumatic events--some reporting multiple types of events, others reporting multiple events of the same type--the range is 1 to over 30. See the scatter plots below for more details, which include sample size for studies reporting number of traumas experienced and counts of traumatic events participants experienced.