Is It Time to Replace the Oswestry Index With PROMIS Physical Function Computer Adaptive Test?

Objective: To address the relative influence of psychological factors on variation in Patient-Reported Outcomes Measurement Information System (PROMIS) Physical Function (PF) Computer Adaptive Test (CAT) and Oswestry Low Back Pain Disability Index (ODI) scores.

Design: Cross-sectional.

Setting: We enrolled patients with low back pain, presenting to clinicians specializing in the treatment of spine conditions in a large urban area.

Participants: New and return English-speaking patients (N=116).

Main Outcome Measures: The PF CAT and ODI.

Methods: Patients completed the Pain Catastrophizing Scale short form, Patient Health Questionnaire short form (PHQ-2), Pain Self-Efficacy Questionnaire short form (PSEQ-2), PROMIS PF CAT and ODI on a secure tablet.

Results: The 95% CI for the amount of variation in PROMIS PF CAT scores (95% CI, 0.06-0.31) accounted for by psychological measures overlapped with the 95% CI for the amount of variation in ODI scores (CI, 0.26-0.53). PROMIS PF CAT had a strong correlation with ODI (r=-0.69; P<.001). Greater PROMIS PF CAT scores were independently associated with fewer symptoms of depression (β=-1.6; 95% CI, -2.7 to -0.58; P=.003). Higher ODI scores were independently associated with more catastrophic thinking (β=1.2; 95% CI, 0.60-1.88; P<.001) and less self-efficacy (β=-2.4; 95% CI, -3.2 to -1.5; P<.001). PSEQ-2 accounted for the largest proportion of variation in ODI. PHQ-2 accounted for the largest proportion of variation in PROMIS PF CAT. Psychological measures explained more variation in ODI (semipartial R=0.48 for psychological measures; adjusted R full model=0.49) than in PROMIS PF CAT (semipartial R=0.17 for psychological measures; adjusted R full model=0.31).

Conclusions: The ODI and PROMIS PF CAT are comparably sensitive to psychological factors in patients with persistent lower back pain. Given that the PROMIS PF CAT is more efficient to administer, clinicians might consider using PROMIS PF CAT when assessing physical limitations in patients with persistent lower back pain.