Patient Health Questionnaire-15 (PHQ-15)

The Patient Health Questionnaire (PHQ-15) is a somatic symptoms subscale derived from a self- administered version of the Primary Care Evaluation of Mental Disorders (PRIME-MD) diagnostic instrument for common mental disorders. The PRIME-MD was an questionnaire developed and validated in the early 1990s to efficiently diagnose five of the most common types of mental disorders presenting in medical populations: depressive, anxiety, somatoform, alcohol, and eating disorders. The PHQ-15 is simple, quick, unrestricted, and international but may not be ideal for all purposes.

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. It’s not however ideal as a diagnostic questionnaire, as it alone is insufficient to meet the full diagnostic criteria required for a DSM-V diagnosis of Somatic Symptom Disorder. The PHQ-15 has a sensitivity of 78% and specificity of 71% for a DSM-IV diagnosis of somatoform disorder. It’s important to keep in mind if you are using the PHQ-15 as a screening tool, false positives can include Panic disorder, Generalized anxiety disorder, Depressive disorders, Illness anxiety disorder, functional neurological symptom disorder, Delusional disorder, Body dysmorphic disorder, or Obsessive-compulsive disorder.

The PHQ -15 is comprised of 15 somatic symptoms that account for more than 90% o the physical symptoms reported, excluding upper respiratory symptoms, of the questions 13 of them are related to physical symptoms, however two physical symptoms - feeling tired or having little energy, and trouble sleeping – are also associated with depression and part of the PHQ-9 questionnaire.

Ideally the PHQ-15 can serves as an continuous measure of somatic symptom (physical) severity and the PHQ-15 score illustrates more clearly the relationship between graded increases in somatic symptom severity and various health outcomes. Allowing the PHQ-15 to track changes in the severity of the individual’s somatic symptoms over time, the measure may be completed at regular intervals as clinically indicated, depending on the stability of the individual’s symptoms and treatment status. Consistently high scores on a particular domain may indicate significant and problematic areas for the patient that might warrant further assessment, treatment, and follow-up.