Decision Analysis in Quest of the Ideal Treatment in Adult Spinal Deformity Adjusted for Minimum Clinically Important Difference.

BACKGROUND: Surgery appears to yield better results in adult spinal deformity treatment when fixed minimum clinically important difference values are used to define success. Our objective was to analyze utilities and improvement provided by surgical versus nonsurgical treatment at 2 years using Oswestry Disability Index with treatment-specific minimum clinically important difference values. METHODS: From a multicenter database including 1452 patients, 698 with 2 years of follow-up were analyzed. Mean age of patients was 50.95 ± 19.44 years; 580 patients were women, and 118 were men. The surgical group comprised 369 patients, and the nonsurgical group comprised 329 patients. The surgical group was subcategorized into no complications (192 patients), minor complications (97 patients) and major complications (80 patients) groups to analyze the effect of complications on results. Minimum clinically important differences using Oswestry Disability Index were 14.31, 14.96, and 2.48 for overall, surgical, and nonsurgical groups. Utilities were calculated by visual analog scale mapping. RESULTS: Surgical treatment provided higher utility (0.583) than nonsurgical treatment (0.549) that was sensitive to complications, being 0.634, 0.564, and 0.497 in no, minor, and major complications. Probabilities of improvement, unchanged, and deterioration were 38.3%, 39.2%, and 22.5% for surgical treatment and 39.4%, 10.5%, and 50.1% for nonsurgical treatment. Improvement in the surgical group was also sensitive to complications with rates of 40.1%, 39.3%, and 33.3%. CONCLUSIONS: Our results suggest that surgical treatment has less disease burden and less chance of deterioration, but equal chances for improvement at 2 years of follow-up. As it appears to be a better modality in the absence of complications, future efforts need be directed to decreasing the complication rates.