Importance of Outcome Domain for Patients With Musculoskeletal Pain: Characterizing Subgroups and Their Response to Treatment.

Background: Patient-centered care models allow for the ability to tailor treatment to outcomes of importance to patients.

Objective: The purposes of this study were to (1) define patient subgroups based on outcomes of importance; (2) determine whether patient subgroups based on outcomes of importance differed in demographic, clinical, and psychological measures; and (3) determine whether outcome domain subgroups differed in treatment responses.

Design: This was a prospective, longitudinal observational study.

Methods: This was a secondary analysis of the Optimal Screening for Prediction of Referral and Outcome study. Patients in the development phase completed the Patient Centered Outcome Questionnaire (PCOQ) and questionnaires related to negative mood, fear avoidance, and positive coping, as well as region-specific questionnaires. Patients in the validation cohort completed the PCOQ, measures of treatment satisfaction and region-specific questionnaires at 4 weeks, 6 months, and 1 year. A hierarchical agglomerative cluster analysis identified profiles based on importance outcomes as determined by the PCOQ. Analysis of variance and chi-squared assessed baseline subgroup differences in demographics, psychological factors, and clinical outcomes. Repeated-measure analysis of variance considered subgroup differences in outcomes longitudinally.

Results: Cluster analysis identified 3 subgroups: (1) "Multiple Outcome Domains Important" subgroup characterized by high importance attached to improvement in all domains, (2) "Pain and Function Outcomes Important" subgroup characterized by high importance attached to improvement in pain and interference, and (3) "Pain Important" subgroup characterized by greatest importance attached to improvement in pain.

Limitations: Our sample included patients from outpatient physical therapy and may not be representative of patients in other settings.

Conclusion: Patients can be characterized by the importance attached to improvement in outcome domains. The identified subgroups differed in baseline measures as well as response to treatment.