Abstract
OBJECTIVE
The Scoliosis Research Society-22 (SRS-22) is a legacy measure used to assess patient-reported outcomes of disease-related disability in adult spinal deformity (ASD), while the Patient-Reported Outcomes Measurement Information System (PROMIS) collects health domain scores (for example, Function) and offers a score relative to population norms. The authors sought to create linkage tables to allow comparison of prior outcomes research in ASD with the SRS-22 to more recent studies using PROMIS.
METHODS
Patients with symptomatic lumbar scoliosis were enrolled and treated in a combined randomized and observational study and completed SRS-22 and PROMIS Function, Pain Interference, Anxiety, and Depression questionnaires at visits 2 to 8 years after enrollment. Correlations between the SRS-22 and PROMIS domains identified the most appropriate PROMIS domains for each of 3 SRS-22 subscales (Pain, Function, and Mental Health); equipercentile linking constructed linkages. Linkages were evaluated on the basis of bias, error, and criterion-related validity with other patient-reported outcome measures (PROMs), demographic characteristics, and treatment arm.
RESULTS
PROMIS Physical Function linked with SRS-22 Function (r = 0.80, 95% CI 0.75–0.84), PROMIS Pain Interference with SRS-22 Pain (r = −0.75, 95% CI −0.80 to −0.69), and PROMIS Anxiety with SRS-22 Mental Health (r = −0.71, 95% CI −0.79 to −0.62). Smoothing the linking functions yielded little difference in performance (bias, linking error); thus, smoothing was used to construct more continuous crosswalk tables linking the measures. Linking error was modest, suggesting linked scores are most useful for group mean, rather than individual, comparisons. Linkages are useful for yielding comparable scores to compare demographic groups (sex, age) and treatment arms (operative, nonoperative) in clinical research, but scores are not comparable in their relationships with related PROMs.
CONCLUSIONS
Linkages between SRS-22 and PROMIS domains allow data harmonization for comparing results of clinical and epidemiological research. Neither sex, age, nor treatment arm affected the interchangeability of the linked scores. There is a need for a PROMIS Self-Image instrument.