Minimum Detectable Measurement Difference for Health-Related Quality of Life Measures Varies With Age and Disability in Adult Spinal Deformity: Implications for Calculating Minimal Clinically Important Difference

Study Design. Retrospective cohort. Objective. To investigate the minimum detectable measurement difference (MDMD) in the Scoliosis Research Society-22r (SRS-22r) outcomes instrument in adult spinal deformity (ASD) and to evaluate the effect of baseline data on measurable difference. Summary of Background Data. The minimum clinically important difference (MCID) is the smallest, clinically relevant change observed and has been proposed for the SRS-22r instrument in ASD as 0.4. The MCID must be greater than the MDMD to be useful. The MDMD for the SRS-22r has not been calculated, nor have the effect of patient baseline values on MDMD. Methods. A prospective observation cohort was queried for patients treated both operatively and nonoperatively for ASD. Patients with baseline and 1-year, 2-year follow-up SRS-22r data were included in the analysis. The MDMD was calculated using classical test theory and item-response theory methods. Effect size and standardized response means were calculated. The effect of baseline data values was evaluated for MDMD. Results. A total 839 Patients were eligible for cohort inclusion with 428 (51%) eligible for analysis with complete data. MDMD for Pain (0.6) and Self-Image (0.5) were greater than 0.4. MDMD varied with age (highest for the youngest patients) and with disability (highest for SF-36 Physical Component Summary
Source: Spine - Category: Orthopaedics Tags: Health Services Research Source Type: research