Comorbid post-traumatic stress symptoms in an urban population of mothers screening positive for depression

Introduction

Screening for maternal depression in clinical and community settings has been the topic of numerous recent studies and an important component of the 2009 Institute of Medicine (IOM) report, Depression in Parents, Parenting, and Children.¹ According to the IOM report, however, studies of maternal depression screening have largely ignored the implications of comorbid mental health conditions on screening approaches and evaluation of screening effectiveness.¹ One condition that may accompany – and complicate – maternal depression is posttraumatic stress disorder (PTSD).

PTSD and depression share several diagnostic criteria, and depression – when accompanied by posttraumatic stress symptoms – is less responsive to treatment.² Whereas depression has an extensive evidence-base for effective primary care-based treatment, PTSD typically requires mental health specialty services. In certain high risk populations, therefore, it is important to understand the likelihood with which depression screening instruments identify mothers who may have PTSD.

Methods

We surveyed mothers with children aged 0 to 5 from WIC offices and Head Start centers in a single city. Research assistants approached all mothers in WIC office waiting rooms; Head Start mothers were recruited through study flyers and by Head Start staff unaware of the study’s specific purpose. Ability to communicate in English or Spanish was the eligibility criterion.

Respondents answered a face-to-face questionnaire, which included the Patient Health Questionaire-2 (PHQ-2) and the Modified PTSD Symptom Scale (PSS). The PHQ-2 is a 2-item depression screening instrument with performance characteristics of 83% sensitivity and 92% specificity for major depression.³ The PSS is a valid scale of PTSD symptomatology.⁴ Consistent with previous literature,⁵ we created a proxy variable for PTSD diagnosis by mapping individual PSS items onto DSM-IV diagnostic criteria.

Data Analysis comprised descriptive statistics. The Boston Medical Center IRB approved this study.

Results

From a total sampling frame of 5426, we surveyed 190 mothers. 110 (58%) reported English as their primary language; 55 (30%), Spanish. Seventy-seven women (41%) self-identified as black; 75 (39%), Latina. On average, the mothers had 2.16 children (SD 1.27); the majority of mothers were less than 30 years-old; and 43% worked outside the home.

Of 190 mothers, 56 (29%) screened positive for depression and 32 (17%) had symptoms consistent with DSM-IV criteria for PTSD. Of the 56 women with positive depression screens, 14 (25%) had symptoms consistent with PTSD. Thirty-one women had both positive depression screens and reported histories of trauma; of these, 45% had symptoms consistent with PTSD.

In our sample, 89 women (47%) reported having an unusually traumatic event in their lifetime. The most common traumas were sexual assault, physical assault, witnessing someone shot or killed, and witnessing the death of a family member. Among those having experienced a trauma, 32 (36%) had symptoms consistent with PTSD.

Discussion

A screening test is indicated if it accurately identifies a condition, which can then be treated effectively. According to the US Preventive Services Task Force, adult depression fits these criteria, provided that appropriate systems exist to ensure accurate diagnosis, and appropriate follow-up and treatment.⁶ However, when depression is comorbid with post traumatic stress symptoms – as it appears to be in 25% of our sample – it is both more difficult to diagnose and more refractory to treatment. Among populations in which this comorbidity is highly prevalent, depression may no longer fit the paradigm for a good screening test, given current screening practices and availability of services.

In order to fulfill the USPSTF’s criteria for diagnostic accuracy and appropriate follow-up and treatment, therefore, it may be that maternal depression screening in certain settings ought to be augmented with additional questions around trauma exposure or symptomatology, and that more detailed screening – accompanied by algorithms for referral – may be warranted. Given the limited mental health resources for low-income populations, the high prevalence of maternal depression, and the benefits to children of treating depressed mothers, resolving these issues is of substantial public health importance.