Purpose: Because recognition and management of patients with somatoform disorders are difficult, we wanted to determine the specificity, sensitivity, and the test-retest reliability of the 15-symptom Patient Health Questionnaire (PHQ-15) for detection of somatoform disorders in a high-risk primary care population.
Methods: We studied the performance of the PHQ-15 in comparison with the Structured Clinical Interview for the Diagnostic and Statistical Manual-IV Axis I disorders (SCID-I) as a reference standard. From January through September 2006, we approached patients for participation. This study was conducted in primary care settings in the Netherlands. Patients aged between 18 and 70 years were eligible if they belonged to 1 or more of the following groups: (1) patients with unexplained somatic complaints, (2) frequent attenders, and (3) patients with mental health problems. For the SCID-I interview we invited all patients with a PHQ-15 score of 6 or greater and a random sample of 30% of patients with a PHQ-15 score of less than 6. The primary study outcomes were the sensitivity and specificity for the validity and the kappa coefficient for the test-retest reliability.
Results: Of 2,147 eligible patients, 906 (42%) participated (mean age 48 years, 62% female). At a cutoff level of 3 or more severe somatic symptoms during the past 4 weeks, sensitivity was 78% and specificity 71%. The test-retest reliability was 0.60.
Conclusions: The PHQ-15 is a valid and moderately reliable questionnaire for the detection of patients in a primary care setting at risk for somatoform disorders.