Abstract
BACKGROUND: Previous studies have identified patient and surgical factors associated with patient-reported outcomes measurement information system (PROMIS)-physical function (PF) minimal clinically important difference (MCID) rates after lumbar fusion, but investigation into the timing of MCID achievement remains limited. This study aimed to assess whether time to MCID achievement differed across patients presenting with mild, moderate, or severe disability as measured using the PROMIS-PF instrument. METHODS: A retrospective review of 144 patients undergoing 1- to 3-level lumbar fusion from 2020 to 2023 was performed. All patients completed PROMIS-PF surveys at baseline and 1 year postoperatively. Patients were classified as mild (PROMIS-PF > 40), moderate (30-40), or severe (<30) disability based on baseline PROMIS-PF T-scores. MCID achievement rates and time to MCID were compared across groups using univariate and multivariate analyses. Multivariate Cox proportional hazard models were used to assess the relationship between baseline disability and MCID achievement rates over time. RESULTS: Twenty (13.9%) patients presented with mild disability, 92 (63.9%) with moderate disability, and 32 (22.2%) with severe disability. The overall rate of 1-year postoperative MCID achievement was 59%. After adjusting for American Society of Anesthesiologists scores and Charlson Comorbidity Index, severe baseline disability was associated with increased odds of early MCID achievement (<90 days; OR = 2.95, P = 0.015) and shorter days to MCID achievement. In the adjusted Cox models, patients with severe baseline disability demonstrated increased MCID achievement at any time over the 1-year postoperative period when compared with the mild disability (HR = 3.52, P = 0.005) and moderate disability (HR = 1.85, P = 0.020) groups. CONCLUSION: Patients presenting with severe disability were more likely to achieve clinically significant improvements in function across time points during the 1-year postoperative period. Furthermore, these patients demonstrated higher rates of early MCID achievement and less time to MCID than those with moderate or mild baseline disability. Utilization of PROMIS-PF may assist with preoperative patient selection and expectation setting. CLINICAL RELEVANCE: In the clinical setting, establishing realistic recovery expectations is a critical aspect of the surgeon-patient relationship. The data presented in the current study may be used in preoperative consultations to provide patients with a depiction of their potential improvement in physical function over time based on their baseline level of function. Postoperatively, the data may serve as a benchmark for assessing an individual's recovery trajectory compared to historically similar patients.