Psychopathology and Health-related Quality of Life As Patient-reported Treatment Outcomes: Evaluation of Concordance Between the Brief Symptom Inventory (BSI) and the Short Form-36 (SF-36) in Psychiatric Outpatients

Purpose: Treatment outcome for common psychiatric disorders, such as mood and anxiety disorders, is usually assessed by self-report measures regarding psychopathology [e.g., via Brief Symptom Inventory (BSI)]. However, health-related quality of life [as measured by the 36-item Short-Form Health Survey (SF-36)] may be a useful supplementary outcome domain for routine outcome monitoring (ROM). To date, the assessment of both outcomes has become fairly commonplace with severe mental illness, but this is not yet the case for common psychiatric disorders. The present study examined among outpatients with common psychiatric disorders whether aggregate assessments of change across treatment regarding psychopathology and health-related quality of life yield similar results and effect sizes.

Methods: We compared treatment outcome on the BSI and the SF-36 in a sample of 13,423 outpatients. The concordance of both instruments was assessed at various time points during treatment.

Results: Scores on both instruments were associated, but not so strongly to suggest they measure the same underlying construct. The SF-36 scales presented a varied picture of treatment outcome: understandably, patients changed more on the mental component scales than on physical component scales. Outcome according to the BSI was quite similar to outcome according to scales of the SF-36 that showed the largest change.

Conclusions: Although (mental health) scores on both instruments are associated, adding the SF-36 in addition to the BSI in treatment evaluation research produces valuable information as the SF-36 measures a broader concept and contains physical/functional component scales, resulting in a more complete clinical picture of individual patients.