Population-based prevalence of somatic symptom disorder and comorbid depression and anxiety in Taiwan

Objective: The nationwide prevalence of somatic symptom disorder (SSD) has not yet been investigated in Asia. SSD is often comorbid with depression and anxiety, and the effects of these conditions on medical utilization await clarification. We hence performed a study in Taiwan to explore these issues.Methods: Using telephone-based sampling and interview, we obtained data for 3161 participants whose age, gender and living area were compatible with the Taiwan population. We gathered scores of the Patient Health Questionnaire-15 (PHQ-15), Health Anxiety Questionnaire (HAQ) and Patient Health Questionnaire-4 (PHQ-4). Individuals with a PHQ-15 score of at least 4 and a HAQ score of at least 17 were considered to have SSD. Descriptive statistics were used to clarify the prevalence and normative data of the questionnaires. We used multiple logistic regression analyses to investigate the relation between diagnoses and medical utilization. Results: The prevalence of SSD was 5.00% and women had a higher SSD prevalence than men; participants aged 40-49 years had the highest SSD prevalence. In SSD patients, 33.58% had depression or anxiety. After correcting for demographics, SSD and anxiety (but not depression) were associated with a significantly high level of outpatient/emergency department attendance. Comorbid depression or anxiety did not significantly increase the medical utilization of SSD patients.Conclusion: The nationwide SSD prevalence in Taiwan is compatible with the description in the DSM-5. The comorbidity of SSD and depression/anxiety is common, but depression or anxiety does not significantly increase the SSD patients' medical utilization.