psychiatry & behavioral healthquestionnaire

PHQ-15 (Somatic Symptom Severity)

The PHQ-15 measures somatic symptom severity across 15 common physical symptoms. Each item is scored 0–2 ('not bothered' to 'bothered a lot'), with total scores ranging from 0 to 30. Higher scores correlate with functional impairment, healthcare utilisation, and comorbid psychiatric conditions.

questionnaire

when to use

Use in primary care for patients presenting with multiple somatic complaints, particularly when somatic symptom disorder, health anxiety, or somatisation is suspected. Also useful as a research measure of somatic symptom burden. Administer alongside PHQ-9 and GAD-7 for a comprehensive brief mental health assessment.

when not to use

PHQ-15 measures symptom severity, not cause. High scores do not distinguish medically explained from unexplained symptoms — clinical evaluation is essential. A high PHQ-15 in a patient with multiple medical conditions may simply reflect disease burden, not somatisation. Not a diagnostic tool for somatic symptom disorder.

clinical pearls

  • The PHQ-15 is most useful when administered alongside PHQ-9 and GAD-7. Together, these three tools cover the most common primary care mental health presentations: depression, anxiety, and somatic symptoms.
  • A high PHQ-15 with normal PHQ-9 and GAD-7 may suggest somatic symptom disorder or health anxiety rather than depression/anxiety. Conversely, a high PHQ-15 with elevated PHQ-9 often reflects the somatic manifestations of depression.
  • Items 14 (fatigue) and 15 (sleep) overlap with depression symptoms on the PHQ-9. This is by design — these symptoms sit at the intersection of somatic and depressive presentations.
  • Do not equate 'high PHQ-15' with 'medically unexplained symptoms'. The PHQ-15 measures how much symptoms bother the patient, regardless of cause. Always complete appropriate medical workup.
  • The PHQ-15 can track symptom burden over time, which is useful for monitoring patients with chronic pain, fibromyalgia, or functional disorders.