Paroxetine for patients with undifferentiated somatoform disorder: A prospective, open-label, 8-week pilot study

Background: Forty-eight percent of somatic symptoms encountered in the primary care setting are medically unexplained. Such symptoms have been associated with negative impact on quality of life and with functional impairment. Objective: The aim of this study was to assess the potential utility and tolerability of paroxetine for the treatment of undifferentiated somatoform disorder (USD), using the 15-item Patient Health Questionnaire (PHQ-15) to assess the severity of somatic symptoms. Methods: A prospective, open-label, 8-week pilot study of paroxetine was conducted in outpatients with USD. Data were collected at baseline and at weeks 1, 2, 4, and 8. The primary measure was the mean change in PHQ-15 total score from baseline to the end of treatment. Secondary effectiveness measures included mean changes in total scores on the Beck Depression Inventory (BDI) and the 12-item General Health Questionnaire from baseline to end of treatment. A physical examination, electrocardiography, complete blood count, blood chemistry, urinalysis, and pregnancy test (for women of childbearing potential) were performed at baseline and the end of treatment. Vital signs were measured during each visit. Adverse events (AEs) were recorded during the study and included those determined using the Systematic Assessment for Treatment Emergent Events-General Inquiry. Results: Forty-three Korean patients were screened for the study. Twenty-two patients (13 women, 9 men; mean [SD] age, 37.4 [12.4] years) were enrolled and 20 completed the study; 2 patients were lost to follow-up. The mean total score on the PHQ-15 from baseline to the end of treatment was significantly decreased (17.2 vs 4.3; P = 0.001), as was the mean total BDI score (12.8 vs. 6.3; P < 0.001). Overall, paroxetine was well-tolerated. Nausea and dry mouth were the most commonly reported treatment-emergent AEs (both, 5 [22.7%]); no serious AEs were reported. No abnormal laboratory results were observed. Conclusion: This open-label pilot study found that paroxetine had potential utility in the treatment of USD and was generally well-tolerated. These results suggest that adequately-powered, double-blind, placebo-controlled trials are warranted to more fully assess the efficacy and safety of paroxetine in the treatment of USD.