Estimating the minimum clinically important difference (MCID) of the five-repetition sit-to-stand test in patients with lumbar disc herniation.

Abstract

The impact of surgical interventions on lumbar disc herniation (LDH) is often assessed using objective functional impairment (OFI) tests like the five-repetition sit-to-stand (5R-STS) test. This study calculates the minimum clinically important difference (MCID) for 5R-STS improvement in patients with LDH one year after surgery. Adult patients with LDH scheduled for surgery were prospectively recruited from a Dutch short-stay spinal clinic. The 5R-STS time, Oswestry Disability Index (ODI), Roland-Morris Disability Questionnaire (RMDQ), Numeric Rating Scale for back and leg pain, EQ-5D-3L health-related quality of life questionnaire and EQ5D-VAS were recorded preoperatively, at 6-weeks and 1-year post-operatively. The MCID was calculated using anchor-based methods (within-patient change; between-patient change; and receiver-operating characteristic approaches) and distribution-based methods (0.5 standard deviation (SD); effect size; standard error of measurement; standardized response mean; and 95% minimum detectable change (MDC)). The final MCID value was based on the "gold standard": an averaging of the anchor-based methods using ODI and RMDQ as the closest available anchors. We prospectively recruited 134 patients. One-year follow-up was completed by 103 (76.8%) of patients. The MCID values derived using different methods varied from 0.7 to 5.1 s (s). The final, averaged, anchor-based MCID for improvement was 3.6 s. Within distribution-based methods, 95% MDC and 0.5SD approach, yielded an MCID of 3.0 and 3.8 s, respectively, aligning closely with the overall anchor-derived MCID for 5R-STS. In a patient with LDH, an improvement in 5R-STS performance of at least 3.6 s can be regarded as a clinically relevant improvement.