Journal of clinical sleep medicine : JCSM : official publication of the American Academy of Sleep MedicineOct 9, 2015

Minimal Important Change in Restless Legs Syndrome Severity Based on Two Clinical Trials

Circadian Biology Weekly Brief ↗PubMed ↗DOI ↗

Updated Mar 29, 2026

Abstract

The minimal clinically important change (MCIC) total IRLS cut-off score was found to be -9 for significant improvement in patients treated with the rotigotine transdermal system.

The MCIC cut-off score for 'much improved vs minimally improved' was -9, indicating a meaningful change in symptoms.
For 'much improved/very much improved vs minimally improved or worse,' the MCIC cut-off score was -11, suggesting a higher threshold for significant clinical improvement.
The MCIC score of -9 also applied for the comparison of 'minimally improved or better vs no change or worse,' reflecting consistent findings across analyses.
Similar MCIC cut-off scores were observed in two separate studies, SP790 and SP792, reinforcing the reliability of the results.
Receiver operating characteristic (ROC) analysis was used to establish these MCIC values based on patient-reported outcomes.

Simplified

STUDY OBJECTIVES: Determine the minimal clinically important change (MCIC), a measure determining the minimum change in scale score perceived as clinically beneficial, for the international restless legs syndrome (IRLS) and restless legs syndrome 6-item questionnaire (RLS-6) in patients with moderate to severe restless legs syndrome (RLS/Willis-Ekbom disease) treated with the rotigotine transdermal system.

METHODS: This post hoc analysis analyzed data from two 6-mo randomized, double-blind, placebo-controlled studies (SP790 [NCT00136045]; SP792 [NCT00135993]) individually and as a pooled analysis in rotigotine-treated patients, with baseline and end of maintenance IRLS and Clinical Global Impressions of change (CGI Item 2) scores available for analysis. An anchor-based approach and receiver operating characteristic (ROC) curves were used to determine the MCIC for the IRLS and RLS-6. We specifically compared "much improved vs minimally improved," "much improved/very much improved vs minimally improved or worse," and "minimally improved or better vs no change or worse" on the CGI-2 using the full analysis set (data as observed).

RESULTS: The MCIC IRLS cut-off scores for SP790 and SP792 were similar. Using the pooled SP790+SP792 analysis, the MCIC total IRLS cut-off score (sensitivity, specificity) for "much improved vs minimally improved" was -9 (0.69, 0.66), for "much improved/very much improved vs minimally improved or worse" was -11 (0.81, 0.84), and for "minimally improved or better vs no change or worse" was -9 (0.79, 0.88). MCIC ROC cut-offs were also calculated for each RLS-6 item.

CONCLUSIONS: In patients with RLS, the MCIC values derived in the current analysis provide a basis for defining meaningful clinical improvement based on changes in the IRLS and RLS-6 following treatment with rotigotine.

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Minimal Important Change in Restless Legs Syndrome Severity Based on Two Clinical Trials

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