Frequently Asked Questions

In this veteran sample, major depressive disorder was associated with worse PTSD outcomes within prolonged exposure (PE). Veterans in PE who had MDD improved significantly less on CAPS-5 PTSD symptom severity than those without MDD (t30=-2.16, P=.04), and they were also significantly less likely to achieve loss of PTSD diagnosis (χ2=3.86, P=.049) and remission (χ2=4.57, P=.033).

The authors noted that this pattern was consistent with the overall conclusion that comorbid MDD was linked to less PTSD improvement in the trauma-focused treatment.

No. Within interpersonal psychotherapy (IPT), veterans with and without current major depressive disorder did not differ significantly in PTSD outcomes. Although patients with MDD entered treatment with higher baseline PTSD severity, the amount of CAPS-5 symptom change did not differ by MDD status, and there were no differences by MDD status on categorical PTSD outcomes.

Interpersonal psychotherapy had better treatment retention overall than prolonged exposure. Among all veterans who started treatment, 22.4% of IPT patients completed fewer than 8 sessions compared with 53% of PE patients, and IPT patients completed more sessions on average than PE patients (mean 9.8 vs 7.1; t=3.66, P<.001).

The study defined treatment completion as attending at least 8 sessions.

No. In this study, MDD did not increase noncompletion within prolonged exposure. Among PE participants, 38% of those with MDD completed fewer than 8 sessions compared with 63% of those without MDD, which was the opposite direction from the authors' original expectation and did not support the idea that MDD drove poorer retention in PE in this veteran sample.

IPT showed a clinically meaningful but not statistically significant advantage over PE for veterans with both PTSD and MDD. Among patients with MDD, IPT tended toward greater improvement in PTSD symptom severity than PE (t=1.90, P=.07), and treatment response was higher in IPT than PE (48% vs 19%), although the treatments did not differ significantly on loss of PTSD diagnosis or remission.

The authors interpreted these findings as suggesting a possible advantage for IPT in patients with co-occurring MDD, but not a definitive one.

Among veterans without MDD, prolonged exposure had worse retention but one better categorical PTSD outcome than IPT. Noncompletion was significantly more likely in PE than IPT (63% vs 18%; χ2=12.35, P<.001), and PE patients without MDD completed fewer sessions on average than IPT patients without MDD (6.2 vs 10.2; P<.001).

At the same time, for patients without MDD, remission was more likely in PE than IPT (25% vs 4%; χ2=4.02, P=.045), while the treatments did not differ on the other 3 symptom-change indicators reported.

No. The exploratory analyses did not show a significant advantage for IPT over PE on self-reported depression symptoms. Change in PHQ-9 scores did not differ significantly between IPT and PE among veterans with MDD or among those without MDD.

This was a post hoc analysis of a 2-site, single-blinded randomized controlled trial comparing interpersonal psychotherapy and prolonged exposure for military-related PTSD in veterans. Of 115 randomized veterans, 109 started treatment: 58 in IPT and 51 in PE, and 51 of those 109 participants (47%) had current DSM-5 major depressive disorder.

The analysis examined whether MDD moderated treatment retention and PTSD outcomes, but the original trial was not designed or powered to test the treatment-by-time-by-MDD interaction definitively. That means subgroup findings, especially trends and marginally significant differences, should be interpreted cautiously.

The main limitations were small subgroup sample sizes, lack of statistical power for testing interactions by treatment and MDD status, and no adjustment for multiple comparisons in this exploratory analysis. The authors also noted high noncompletion rates for PE, restriction of the sample to veterans with war-zone service, and a nearly all-male sample, which limits generalizability to women and to nonveteran populations.

In addition, depression was defined only as current DSM-5 MDD, and variation across studies in how depression and dropout are defined makes comparisons with other research more difficult.

This study suggests that interpersonal psychotherapy may be a reasonable non-trauma-focused option for veterans with PTSD and comorbid MDD. In this sample, MDD was associated with significantly less PTSD improvement within prolonged exposure, whereas IPT outcomes did not differ by MDD status, and IPT showed a nonsignificant but clinically meaningful advantage over PE on PTSD response among patients with MDD (48% vs 19%).

The authors concluded that the accumulating evidence suggests a possible advantage for IPT relative to trauma-focused treatment in patients with co-occurring MDD, while also emphasizing that this question needs replication in studies specifically designed and powered to test it.