Patient-related and radiographic predictors of inferior health-related quality-of-life measures in adult patients with nonoperative spinal deformity

Peter G. Passias, Haddy Alas, Shay Bess, Breton G. Line, Virginie Lafage, Renaud Lafage, Christopher P. Ames, Douglas C. Burton, Avery Brown, Cole Bortz, Katherine Pierce, Waleed Ahmad, Sara Naessig, Michael P. Kelly, Richard Hostin, Khaled M. Kebaish, Khoi D. Than, Pierce Nunley, Christopher I. Shaffrey, Eric O. KlinebergJustin S. Smith, Frank J. Schwab

Research output: Contribution to journalArticlepeer-review


OBJECTIVE Patients with nonoperative (N-Op) adult spinal deformity (ASD) have inferior long-term spinopelvic alignment and clinical outcomes. Predictors of lower quality-of-life measures in N-Op populations have yet to be sufficiently investigated. The aim of this study was to identify patient-related factors and radiographic parameters associated with inferior health-related quality-of-life (HRQOL) scores in N-Op ASD patients. METHODS N-Op ASD patients with complete radiographic and outcome data at baseline and 2 years were included. N-Op patients and operative (Op) patients were propensity score matched for baseline disability and deformity. Patientrelated factors and radiographic alignment parameters (pelvic tilt [PT], sagittal vertical axis [SVA], pelvic incidence [PI]- lumbar lordosis [LL] mismatch, mismatch between cervical lordosis and T1 segment slope [TS-CL], cervical-thoracic pelvic angle [PA], and others) at baseline and 2 years were analyzed as predictors for moderate to severe 2-year Oswestry Disability Index (ODI > 20) and failing to meet the minimal clinically importance difference (MCID) for 2-year Scoliosis Research Society Outcomes Questionnaire (SRS) scores (< 0.4 increase from baseline). Conditional inference decision trees identified predictors of each HRQOL measure and established cutoffs at which factors have a global effect. Random forest analysis (RFA) generated 5000 conditional inference trees to compute a variable importance table for top predictors of inferior HRQOL. Statistical significance was set at p < 0.05. RESULTS Six hundred sixty-two patients with ASD (331 Op patients and 331 N-Op patients) with complete radiographic and HRQOL data at their 2-year follow-up were included. There were no differences in demographics, ODI, and Schwab deformity modifiers between groups at baseline (all p > 0.05). N-Op patients had higher 2-year ODI scores (27.9 vs 20.3, p < 0.001), higher rates of moderate to severe disability (29.3% vs 22.4%, p = 0.05), lower SRS total scores (3.47 vs 3.91, p < 0.001), and higher rates of failure to reach SRS MCID (35.3% vs 15.7%, p < 0.001) than Op patients at 2 years. RFA ranked the top overall predictors for moderate to severe ODI at 2 years for N-Op patients as follows: 1) frailty index > 2.8, 2) BMI > 35 kg/m2, T4PA > 28°, and 4) Charlson Comorbidity Index > 1. Top radiographic predictors were T4PA > 28° and C2-S1 SVA > 93 mm. RFA also ranked the top overall predictors for failure to reach 2-year SRS MCID for N-Op patients, as follows: 1) T12-S1 lordosis > 53°, 2) cervical SVA (cSVA) > 28 mm, 3) C2-S1 angle > 14.5°, 4) TS-CL > 12°, and 5) PT > 23°. The top radiographic predictors were T12-S1 Cobb angle, cSVA, C2-S1 angle, and TS-CL. CONCLUSIONS When controlling for baseline deformity in N-Op versus Op patients, subsequent deterioration in frailty, BMI, and radiographic progression over a 2-year follow-up were found to drive suboptimal patient-reported outcome measures in N-Op cohorts as measured by validated ODI and SRS clinical instruments.

Original languageEnglish (US)
Pages (from-to)907-913
Number of pages7
JournalJournal of Neurosurgery: Spine
Issue number6
StatePublished - Jun 2021


  • Adult spinal deformity
  • Health-related quality of life
  • Nonoperative
  • Predictor

ASJC Scopus subject areas

  • Clinical Neurology
  • Neurology
  • Surgery


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