Gender differences in posttraumatic stress disorder among primary care patients after the World Trade Center attack of September 11, 2001

Background: Debate surrounds the nature of gender differences in rates of posttraumatic stress disorder (PTSD). Objective: The goal of this st udy was to quantify and explore the reasons for gender differences in rates of PTSD in low income, primary care patients after the World Trade Center (WTC) attack of September 11, 2001. Methods: A survey was conducted at a large primary care practice in New York City 7 to 16 months after the WTC attack. The study involved a systematic sample of primary care patients aged 18 to 70 years. The main outcome measures were the Life Events Checklist, the Posttraumatic Stress Disorder Checklist-Civilian Version, and the Primary Care Evaluation of Mental Disorders Patient Health Questionnaire, all administered by a bilingual research staff. Results: A total of 3807 patients were approached at the primary care clinic. Of the 1347 who meteligibility criteria, 1157 (85.9%) consented to participate. After the addition of the WTC/PTSD supplement to the study, the total number of patients was 992, of whom 982 (99.0%) completed the survey. Both sexes had high rates of direct exposure to the WTC attack and high rates of lifetime exposure to stressful life events. Overall, females had lower rates of exposure to the attack compared with males (P < 0.05). Hispanic females had the highest rate of PTSD in the full sample. Gender differences in rates of PTSD were largely accounted for by differences in marital status and education. The rate of current major depressive disorder (MDD) was higher in females than in males (P < 0.001), and the reverse was true for substance abuse (P < 0.001). Gender differences for MDD and substance abuse persisted even after adjustments for demographic differences between the sexes. Conclusions: The increased rate of PTSD in women attending a primary care clinic was mediatedby their social and economic circumstances, such as living alone without a permanent relationship and with little education or income. The increased rate of MDD in women appeared to be less dependent on these circumstances. These findings have implications for the treatment of women with PTSD in primary care and for research on gender differences in rates of psychiatric disorders.