REVIEW OF: Nøhr AK et al, Psychiatry Res 2021;301:113964

STUDY TYPE: Secondary analysis of a controlled trial

SSRIs are often used in PTSD, but it is not clear that they work for all kinds of trauma. Trials of SSRIs are generally positive in women and people with a history of sexual trauma, while trials involving combat-related trauma tend to be negative. The current study aimed to better identify predictors of ­response.

The investigators recruited patients from an ongoing controlled study of 390 patients with PTSD, conducted in 13 countries including the US. Patients were treated open-label with sertraline (100–200 mg/day) or paroxetine (20–40 mg/day) over 12 weeks, these medications being the two SSRIs with FDA approval in PTSD. All patients had experienced a trauma within the past 15 years, including assault with a weapon (31%), death or harm to someone else (21%), sexual assault (13%), or combat or war-zone experience (10%). Just under half had a history of childhood trauma. Ages ranged from 18 to 75, and 62% were female. Symptoms were tracked with the Clinically Administered PTSD Scale (CAPS) along with a patient-rated scale for depression and anxiety. The investigators used a sophisticated statistical technique called growth mixture modeling to attempt to identify predictors of drug response.

The overall response rate was 58.5%, defined as a 30% reduction in the CAPS. Sertraline and paroxetine were equally effective. Sexual assault and female gender were the main predictors of response, including a childhood history of sexual assault. A longer time between the trauma and the treatment also predicted a faster and higher rate of response. Symptoms of depression and anxiety did not predict response to the SSRI. 

One limitation of the study was the exclusion of patients with active suicidality or a history of recent treatment for major depression, anxiety disorders, or substance use disorders. On the one hand, this pure sample reduces the possibility that responses were due to treatment of comorbid disorders. On the other hand, it limits the generalizability of the findings, as does the high dropout rate (40%).

CARLAT TAKE
You can expect to see better response rates to SSRIs when treating PTSD in women and in individuals with a history of sexual trauma. This study confirms that finding, which is pretty consistent across the clinical trials, and adds a little more. Depressive and anxiety symptoms did not predict response, but those with more distant traumas were more likely to respond to SSRIs.