Approximately 21% of 1,100 women seeking treatment in a CMHC had co-occurring depressive symptoms and childhood sexual abuse histories. Given that this trial recruited from a naturally occurring treatment sample rather than recruiting a sample referred for study participation, the 21% rate is likely representative of this type of clinical setting. Depressed women with sexual abuse histories treated with interpersonal psychotherapy showed more reduction in depressive symptoms, PTSD symptoms, and shame than women who were treated with usual care. Given the 66% rate of comorbid PTSD, it is encouraging that PTSD symptoms were not reactivated and that they improved with interpersonal psychotherapy. Overall, these results suggest that interpersonal psychotherapy was beneficial and had advantages over the usual psychotherapy delivered in a CMHC in producing better treatment engagement and retention, a greater improvement in psychiatric symptoms, and better functioning within the family.
Despite marked improvement, mean depression scores remained elevated after active treatment. Possible contributors to incomplete treatment response include predominance of chronic depression (73% of the sample), high rate of comorbid disorders, interpersonal sequelae of extensive trauma exposure, and socioeconomic disadvantage. Comorbid disorders, including PTSD and borderline personality disorder, are associated with worse treatment outcomes (34
). The interpersonal resources of many women were extremely limited and marked by conflictual family relationships, responsibilities of single parenthood, and social isolation. Practical resource limitations, such as difficulties with transportation, can interfere with women’s ability to maintain treatment involvement (38
Studies of interpersonal psychotherapy for treating depression in predominantly low-income, racially diverse adult samples are scarce, but a recent report by Grote and colleagues (18
) serves as an interesting comparison. In that study of perinatal depression, pregnant women receiving culturally relevant, brief interpersonal psychotherapy had significantly more improved depressive symptoms than those in enhanced usual care. In that study (18
), BDI score improved from 24.3±10.2 pretreatment to 6.0±4.7 six months postpartum. Our study had relatively higher posttreatment scores (22.9±15.5), with participants more severely depressed at study entry (34.4±10.4). What could account for the different outcomes in these two studies? One plausible explanation concerns the effects of comorbid conditions. In our study sample, rates of comorbid PTSD (66% in ours versus 28% in the perinatal study) and borderline personality disorder (37% in ours; not reported in the perinatal study) accounted for significant variability in depression outcomes. In our sample, 86% of participants had at least one comorbid anxiety disorder (versus 56% in the perinatal sample), which could suppress treatment response (34
). Furthermore, depression chronicity in our sample may explain the less robust treatment gains, as was found in a recent meta-analysis of treatments for chronic depression (39
In considering findings from this trial, several limitations should be noted. Our primary aim in this small-scale effectiveness trial of interpersonal psychotherapy was to evaluate whether an evidence-based treatment, when compared with usual care, would improve outcomes. This approach enhances ecological validity, which could increase the likelihood of interpersonal psychotherapy’s adoption in community mental health settings if found to be effective (40
). Results suggest that interpersonal psychotherapy enhanced treatment outcomes, but specific contributory mechanisms could not be discerned. For example, the relative contributions of specific components of interpersonal psychotherapy versus general factors, such as working alliance or therapist enthusiasm, are unknown. It is also possible that antidepressant effects contributed differentially to outcomes: at the 36-week assessment, more interpersonal psychotherapy than usual care participants had antidepressant prescriptions, and self-reported adherence was not significantly different between groups. Given this initial finding in favor of interpersonal psychotherapy, further research should investigate possible contributors to change.
Another factor to consider is that the assessor was aware of treatment assignment, which could have introduced bias. We note, however, that depression outcomes were substantially similar on self-report and interviewer-rated measures. Finally, although participants received $30 compensation for completing each research assessment, some types of assistance that could improve treatment engagement in a low-income population (38
), such as transportation and child care, were not available. Although these “real-world” limitations may have interfered with treatment engagement and completion, this clinical trial was representative of usual care in community mental health.