Psychometric evaluation and normative data for a Swedish version of the Patient Health Questionnaire 15-Item Somatic Symptom Severity Scale

The lack of an available Swedish version of the Patient Health Questionnaire 15-Item Somatic Symptom Severity Scale (PHQ-15) motivated the present psychometric evaluation of such a version as well as providing normative data for the PHQ-15. Data from 3,406 individuals who took part in the Vasterbotten Environmental Health Study in Sweden were used. The respondents constitute a random sample, aged 18 to 79years, stratified for age and sex. They responded to a Swedish translation of the PHQ-15 as well as the Hospital Anxiety and Depression Scale, the Perceived Stress Scale, and the Shirom Melamed Burnout Questionnaire for assessment of convergent validity. The distribution of PHQ-15 scores was positively skewed and mesokurtic in shape, and the internal consistency of the PHQ-15 was satisfactory. Correlation coefficients between PHQ-15 score and the measures of anxiety, depression, stress and mental/physical exhaustion indicate satisfactory validity. Normative data for PHQ-15 scores as well as for categories of somatic symptom severity are provided. The favorable psychometric properties of the Swedish version of the PHQ-15 suggest use of this instrument for quantification of somatization in Swedish and similar populations, and has the advantage of available normative data.