After Spine Deformity Surgery, Most Patients Return to Normal Health Scores — And a Better Measurement Tool Helped Us See It
The first study to evaluate two-year adult spinal deformity surgical outcomes using PROMIS CAT finds that the majority of patients reach normal or near-normal health values — and that PROMIS outperforms legacy measures in capturing the full scope of recovery.
OPENING SUMMARY
For decades, spine surgery research has relied on the same small set of outcome questionnaires to measure how patients feel after surgery. These tools — including the Oswestry Disability Index, the Scoliosis Research Society questionnaire, and numeric pain rating scales — have provided valuable information, but they have a fundamental limitation: they measure how patients compare to their own baseline, not to the broader population. This matters because a patient who moves from severe to moderate disability may appear to be a success story on a traditional outcome measure, even if they remain significantly more impaired than a healthy person their age. This study introduces a fundamentally better lens — and what it reveals is both more informative and more encouraging than prior outcome tools have been able to show.
STUDY SNAPSHOT
Study type – Prospective, multicenter, observational study
Total enrolled – 190 patients
Patients with complete 2-year data – 144 (75.8%)
Mean age at surgery – 62.6 years
Mean preoperative scoliosis – 34.2°
Mean preoperative SVA – 74.2 mm
Mean preoperative PI-LL mismatch – 16.7°
Mean follow-up – 2.3 years
Legacy measures used – SRS-22r, ODI, NRS back and leg pain, VR-12
PROMIS CAT domains assessed – Pain Interference, Physical Function, Satisfaction with Participation in Social Roles, Satisfaction with Participation in Discretionary Social Activities, Depression, Anxiety
Normative comparison – ASD PROMIS scores compared to general population reference values
Published in – Spine, Volume 51, Issue 7, April 1, 2026, pages 451–467
PMID – 41004424
DOI – 10.1097/BRS.0000000000005522
Lead author – Shay Bess, MD
WHY THIS MATTERS
Patient-reported outcome measures — questionnaires that ask patients to describe their own health, function, and wellbeing — are the primary way surgical outcomes are evaluated in adult spinal deformity research. But the tools most commonly used were developed decades ago for specific, narrow purposes. The Oswestry Disability Index measures back pain-related disability. The Scoliosis Research Society questionnaire captures aspects of spinal deformity-specific wellbeing. Numeric rating scales capture pain intensity. All of these tools measure change from a patient's own starting point — but none of them tell us how a patient compares to the general population after surgery.
This limitation matters enormously in practice. A patient who enters surgery with severe disability and exits with moderate disability has improved — and legacy measures will show that improvement. But is that patient now functioning comparably to a healthy person of the same age? Are they able to participate in social roles, maintain their mental health, and engage in daily activities at a normal level? It’s more challenging for legacy tools to answer those questions because they have fewer population-based reference standards.
PROMIS — the Patient-Reported Outcomes Measurement Information System — was developed by the National Institutes of Health precisely to address this gap. PROMIS measures are calibrated against the general United States population, with a mean score of 50 and a standard deviation of 10. This means that a PROMIS score can tell us not just whether a patient improved, but whether they have returned to — or remain below — population-normal function. The computer adaptive testing (CAT) version further improves precision and reduces respondent burden by dynamically selecting questions based on prior answers.
Despite the NIH's recommendation of PROMIS as the preferred patient-reported outcome measure, no prior study had evaluated minimum two-year ASD surgical outcomes using PROMIS CAT. This study fills that gap — and the results provide a more complete and more encouraging picture of what spinal deformity surgery can achieve than any prior publication.
UNDERSTANDING PROMIS CAT
PROMIS (Patient-Reported Outcomes Measurement Information System) is a set of person-centered measures developed through NIH funding that evaluate physical, mental, and social health across a wide range of conditions. Unlike condition-specific tools such as the ODI or SRS-22r, PROMIS measures are calibrated against the general population — meaning scores can be interpreted in the context of what is typical for a healthy adult rather than only with respect to a patient's own baseline.
The computer adaptive testing (CAT) format administers questions dynamically: based on each answer, the system selects the most informative next question from a large item bank, efficiently estimating the patient's true score with fewer questions and less respondent burden than fixed-length questionnaires. PROMIS CAT has demonstrated high reliability and validity across numerous medical conditions and surgical specialties.
In this study, PROMIS CAT was administered across six health domains: Pain Interference, Physical Function, Satisfaction with Participation in Social Roles, Satisfaction with Participation in Discretionary Social Activities, Depression, and Anxiety — providing a multidimensional profile of patient health that no single legacy measure can replicate.
KEY FINDINGS
1. Surgery significantly improved spinal alignment. At a mean follow-up of 2.3 years, surgical treatment produced meaningful improvements in all three radiographic alignment parameters measured: scoliosis improved from 34.2° to 14.7°, sagittal vertical axis improved from 74.2 mm to 34.5 mm, and PI-LL mismatch improved from 16.7° to 4.5° — all statistically significant (p <0.0001). These alignment improvements provide the structural foundation for the functional outcomes reported.
2. All legacy HRQOL and PROMIS scores improved significantly from preoperative to two-year follow-up. Every outcome measure administered — including all legacy tools and all six PROMIS CAT domains — showed statistically significant improvement from baseline to minimum two years postoperatively (all p <0.005). This consistency across both traditional and newer measurement approaches reinforces the validity of the functional improvements observed.
3. Before surgery, 50–85% of patients had moderate-to-severe deficits across all PROMIS domains. Referencing preoperative PROMIS scores against population normative values revealed the full burden of ASD on patient health: between 50% and 85% of patients reported moderate to severe deficits across every health domain measured before surgery. This finding quantifies, in population-referenced terms, how profoundly spinal deformity affects the full spectrum of patient wellbeing — not just pain and disability, but social participation, mental health, and anxiety.
4. After surgery, 52–88% of patients reported normal to mild values across all PROMIS domains. The most striking finding of the study is this near-inversion of the preoperative picture: at minimum two years after surgery, between 52% and 88% of patients were scoring in the normal-to-mild range across all six PROMIS health domains. This means that the majority of patients — measured against general population norms rather than their own baseline — had returned to functional levels comparable to healthy adults. No prior study has demonstrated this using a population-calibrated outcome tool at two-year follow-up in ASD surgery.
5. Social health domains showed the greatest improvement. Among all PROMIS domains assessed, Satisfaction with Participation in Social Roles and Satisfaction with Participation in Discretionary Social Activities demonstrated the greatest improvement from preoperative to postoperative. This finding highlights an often-underappreciated dimension of spinal deformity's impact and surgical recovery: the ability to participate in relationships, community activities, and meaningful daily engagement may be the aspect of health that improves most profoundly — and that legacy outcome tools have been least equipped to capture.
6. PROMIS CAT outperformed legacy measures in evaluating outcomes. The study's title reflects a conclusion supported by its methods: PROMIS CAT demonstrated advantages over legacy HRQOL measures in evaluating ASD surgical outcomes. While the abstract does not detail every specific comparison, the population-referencing capability of PROMIS — and its ability to capture social and mental health domains not assessed by legacy tools — enabled a more comprehensive and informative characterization of postoperative recovery than any single traditional measure could provide.
PRACTICAL IMPLICATIONS
PROMIS CAT should be considered for adoption as a standard outcome measure in ASD surgical programs. The NIH has recommended PROMIS as the preferred patient-reported outcome measure for a reason — and this study demonstrates why that recommendation applies specifically to ASD surgery. PROMIS CAT provides more comprehensive, population-referenced, and precisely measured outcome data than legacy tools. Programs seeking to upgrade their outcome measurement infrastructure have a strong evidence base for this transition.
The 50–85% to 52–88% reversal in PROMIS domain scores is a powerful communication tool for patient counseling. When counseling patients before ASD surgery, the finding that 50–85% of patients enter surgery with moderate-to-severe deficits across all health domains — and that the majority exit with normal or near-normal scores — provides a compelling, evidence-based picture of what surgery can achieve. This framing, grounded in population norms rather than relative improvement, may be more meaningful to patients and families than traditional percentage improvement statistics.
Social health should be explicitly assessed and discussed as a surgical outcome. The finding that social health domains showed the greatest improvement after ASD surgery underscores that spinal deformity affects far more than pain and physical function. Patients who are unable to participate in family activities, maintain friendships, or engage in community life due to their deformity are experiencing a dimension of disability that is not captured by the ODI or SRS-22r. Measuring and communicating this dimension — and documenting its recovery — strengthens the case for surgical intervention and better reflects the full value of successful treatment.
The population-referencing capability of PROMIS enables a higher standard of outcome evaluation. The ability to ask "has this patient returned to population-normal function?" is fundamentally more informative than asking "has this patient improved from their baseline?" Legacy tools can answer the second question. PROMIS can answer both — and for a field seeking to demonstrate surgical value, justify utilization, and optimize patient selection, the ability to document population-level normalization is a significant advance.
Future ASD research designs should incorporate PROMIS alongside legacy measures during the transition period. Because so much existing ASD literature relies on legacy tools, the transition to PROMIS-based reporting is best managed by administering both in parallel — as this study did — allowing for cross-referencing and comparison while the field builds a PROMIS-based evidence base. Studies that administer PROMIS alongside ODI and SRS-22r will enable future meta-analyses to bridge the historical and emerging literatures.
CONCLUSION
This study delivers two important messages simultaneously. The first is methodological: PROMIS CAT, the NIH's recommended patient-reported outcome tool, outperforms legacy measures in evaluating ASD surgical outcomes, providing a more comprehensive, population-referenced, and multidimensional picture of patient recovery. The second is clinical: when viewed through this more precise lens, the majority of adult spinal deformity patients who undergo surgery return to normal or near-normal health scores across all measured domains by two years — including pain interference, physical function, social participation, depression, and anxiety. The near-complete reversal of the preoperative deficit profile — from 50–85% with moderate-to-severe deficits to 52–88% with normal-to-mild values — is among the most compelling demonstrations of surgical efficacy in the ASD literature. For patients, it offers genuine and evidence-based hope. For the field, it establishes a new and higher standard for how surgical success should be measured and communicated.
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