Introduction: Patient reported outcomes measurement information system (PROMIS) is a quality of life metric that has gained increased popularity due to computer adaptive testing. Previous studies have shown that PROMIS correlates with Oswestry Disability Index (ODI) in patients with back pain and takes significantly less time to complete. However, the ability of PROMIS to capture disability from spinal malalignment relative to established metrics is unknown. The aim of the present study is to validate the correlation between ODI and PROMIS in patients with back pain, analyze correlations of PROMIS and legacy metrics to sagittal alignment, and identify major drivers of PROMIS scores and ODI in patients with back pain.
Methods: A retrospective review was conducted of a prospectively collected outcome measures database (PROMIS, ODI, VAS Back, VAS Leg, VAS Neck, and VAS Arm) of spine patients > 18 years. Inclusion criteria for the present study was a chief complaint of back pain and full length weight bearing X-rays within 30 days of health related quality of life (HRQL) completion. Demographic information, radiographic alignment, psychiatric diagnoses, and comorbidities were recorded. PROMIS metrics were correlated to legacy metrics (ODI and VAS). Next, outcome metrics were correlated with sagittal alignment variables T1 Pelvic Angle (TPA), SVA, PT, and PI-LL. Patients were grouped based on the presence of spinal deformity (defined radiographically as any one of SVA > 4 cm, PI-LL > 10°, PT > 20°) and mean HRQL scores were investigated for the adult spinal deformity (ASD) and non-ASD groups. Finally, drivers of PROMIS PF scores and ODI scores were determined using multiple stepwise regression.
Results: 150 patients met inclusion criteria including 60 patients with ASD and 90 patients without. For the whole cohort, PROMIS PF correlated with ODI (r = - 0.651, p < 0.001), VAS Back (r = - 0.260, p = 0.014) and Charleson Comorbidity Index (r = - 0.336, p < 0.001). PROMIS PF had higher correlations than ODI for each sagittal alignment parameter tested, including TPA, SVA, PT, and PI-LL. When patients with ASD were compared to non-ASD patients, the PROMIS score was different between the groups but the ODI and VAS scores were not. Finally, stepwise linear regression showed that SVA, PI-LL, and VAS Leg were significant drivers of PROMIS PF (r2 = 0.406, p < 0.001). VAS Leg and VAS Back were significant contributors to ODI (r2 = 0.376, p < 0.001).
Conclusions: In a cohort of 150 patients with back pain, PROMIS correlated strongly with legacy outcome metrics, including VAS and ODI. PROMIS PF correlated more strongly with sagittal malalignment than ODI. Additionally, patients with spinal deformity had significantly worse PROMIS PF scores but similar ODI scores as patients without ASD. Finally, sagittal alignment was found to be a significant driver of PROMIS PF scores but not ODI scores. PROMIS PF should be utilized as a disability assessment tool in patients with spinal deformity due to ease of use, strong correlations with legacy metrics, and ability to capture disability resulting from sagittal alignment.
Keywords: Disability; PROMIS; Sagittal spinal deformity.