A Patient-Centered Approach to Measuring Treatment Success: The Smallest Worthwhile Effect as an Alternative to the Minimal Clinically Important Difference for PROMs in Adult Idiopathic Scoliosis
DOI:
https://doi.org/10.54640/Keywords:
Adult Idiopathic Scoliosis, Patient-Reported Outcome Measures (PROMs), Smallest Worthwhile Effect (SWE)Abstract
Background: Patient-Reported Outcome Measures (PROMs), such as the Scoliosis Research Society (SRS) questionnaire, are essential for evaluating treatment success in adult idiopathic scoliosis (AdIS). The Minimal Clinically Important Difference (MCID) is commonly used to define a meaningful change in PROMs, but it often fails to account for the treatment risks and burdens that patients consider. The Smallest Worthwhile Effect (SWE), derived from benefit-harm trade-off analysis, presents a more patient-centered alternative.
Objective: To calculate and compare the SWE with the conventional anchor-based MCID for the primary domains of the SRS questionnaire in patients with AdIS.
Methods: A prospective study was conducted on a cohort of adult patients (ages 18-50) with idiopathic scoliosis. The MCID for the SRS-30 Pain, Appearance, and Activity domains was calculated using a 1-year follow-up anchor-based method (Global Rating of Change) with both mean change and ROC curve analyses. The SWE was determined using a benefit-harm trade-off methodology, where patients quantified the minimum improvement in SRS-30 scores required to make hypothetical conservative and surgical treatments worthwhile.
Results: The study included [N] participants (mean age, [X] ± [SD] years; mean Cobb angle, [Y] ± [SD] degrees). Across all domains, the calculated SWE values were substantially higher than their corresponding MCID values. For the Pain domain, the anchor-based MCID was 0.7 (95% CI, 0.5-0.9), whereas the median SWE for justifying a surgical intervention was 1.6 (IQR, 1.3-2.1). Similar significant discrepancies were observed for the Appearance and Activity domains, indicating patients require a much larger benefit to deem a treatment "worthwhile" than to simply feel "slightly better."
Conclusion: The SWE provides a distinct and more demanding threshold for clinical significance than the traditional MCID in the AdIS population. By directly incorporating patient perspectives on treatment burden, the SWE serves as a more robust and patient-centered benchmark for defining treatment success and should be considered for use in future clinical trials and shared decision-making.
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