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The minimal clinically important difference of the motricity index score
Chen Lin1, Yurany A Arevalo1, Richard L Harvey2
1Departments of Neurology, The University of Alabama at Birmingham, Birmingham, AL, USA.
Introduction:
The Motricity Index (MI) can predict motor function after rehabilitation, but its minimal clinically important difference (MCID) has not been established. The primary study aim was to estimate the MCID value of the MI arm score.
Methods:
Between 2017 and 2018, 173 participants hospitalized with confirmed ischemic stroke were recruited into an observational rehabilitation study. Participants with motor weakness as measured by the Fugl-Meyer upper-extremity (FM-UE) and MI with complete baseline and follow-up assessments at 3 months were included in this analysis. The longitudinal recovery of the MI arm score was anchored to having a poor outcome based on the FM-UE recovery (<9) longitudinally. Results reported include the area-under-curve (AUC), along with sensitivity, specificity, and optimal cut-points based on maximizing the Youden statistic.
Results:
Sixty-nine patients (median [IQR] age 70 [18] years; 48% male; 54% white) were included in the final analysis. Mean ± standard deviation outcome scores at 3-months were: MI arm: 83.19 ± 22.80; FM-UE: 53.04 ± 17.26. For the primary results, the MI arm score optimal MCID cutoff for observed recovery was 13 points with a sensitivity of 80% (95% Confidence Interval (CI)(67.6%, 92.4%)) and a specificity of 69.0% (95% CI (52.1, 85.8%)), and the AUC was 0.8082 (0.7007, 0.9157).
Conclusions:
This was the first study to report the MCID of the MI arm score, as anchored to the FM-UE recovery between acute evaluation and 3-months. The estimated optimal MCID of improvement in the MI arm score was 13 points.
Insights
The minimal clinically important difference (MCID) for the Motricity Index (MI) arm score after stroke rehabilitation was estimated at 13 points. This finding helps quantify meaningful motor function recovery in patients post-stroke.
Area of Science:
- Neurology
- Rehabilitation Medicine
- Clinical Measurement
Background:
- The Motricity Index (MI) is a valuable tool for predicting motor function post-rehabilitation.
- However, its minimal clinically important difference (MCID) for the arm score remains unestablished.
- Establishing the MI arm score MCID is crucial for interpreting patient recovery meaningfully.
Purpose of the Study:
- To estimate the minimal clinically important difference (MCID) of the Motricity Index (MI) arm score.
- To provide a quantitative measure for clinically significant motor function improvement after stroke.
Main Methods:
- An observational study analyzed 173 ischemic stroke patients hospitalized between 2017-2018.
- Participants with motor weakness (assessed by Fugl-Meyer upper-extremity (FM-UE) and MI) with complete 3-month follow-up were included.
- The MI arm score recovery was longitudinally anchored to FM-UE recovery (<9) to define a poor outcome.
Main Results:
- Sixty-nine patients were included in the final analysis (median age 70 years).
- The optimal MCID cutoff for the MI arm score was determined to be 13 points.
- This cutoff demonstrated a sensitivity of 80% and specificity of 69.0% with an Area Under the Curve (AUC) of 0.8082.
Conclusions:
- This study provides the first estimation of the MCID for the MI arm score.
- An improvement of 13 points in the MI arm score is considered clinically important post-stroke.
- This finding aids clinicians in evaluating the effectiveness of rehabilitation interventions.
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