Minimal clinically important change in the Toronto Western Spasmodic Torticollis Rating Scale.
Abstract
[OBJECTIVES] To characterize the minimal clinically important change (MCIC) after treatment in cervical dystonia patients using the Toronto Western Spasmodic Torticollis Rating Scale (TWSTRS).
[METHODS] Changes in the TWSTRS from an observational study of abobotulinumtoxinA in the routine management of cervical dystonia (NCT01314365) were analyzed using the Patient Global Impression of Change (PGIC) as anchor.
[RESULTS] For the overall population (N = 304, baseline TWSTRS-Total score 43.4 ± 19.4), the MCIC for the TWSTRS Total score was -11.9 (95%CI: -13.9, -10.0; p < 0.0001). However, thresholds ranged from -3.2 to -18.0 dependent on baseline severity. TWSTRS-Total scores improved linearly by 3 points for every one-point PGIC increase. There was similar linearity between the graded PGIC categories and TWSTRS subscale scores (severity, disability, and pain).
[CONCLUSIONS] A 3-point change is the minimal clinically important change after treatment using TWSTRS as endpoint with higher cutoffs for greater baseline disease severity. For an average trial population (TWSTRS-total: 40-45), a 12-point decrease is clinically meaningful.
[METHODS] Changes in the TWSTRS from an observational study of abobotulinumtoxinA in the routine management of cervical dystonia (NCT01314365) were analyzed using the Patient Global Impression of Change (PGIC) as anchor.
[RESULTS] For the overall population (N = 304, baseline TWSTRS-Total score 43.4 ± 19.4), the MCIC for the TWSTRS Total score was -11.9 (95%CI: -13.9, -10.0; p < 0.0001). However, thresholds ranged from -3.2 to -18.0 dependent on baseline severity. TWSTRS-Total scores improved linearly by 3 points for every one-point PGIC increase. There was similar linearity between the graded PGIC categories and TWSTRS subscale scores (severity, disability, and pain).
[CONCLUSIONS] A 3-point change is the minimal clinically important change after treatment using TWSTRS as endpoint with higher cutoffs for greater baseline disease severity. For an average trial population (TWSTRS-total: 40-45), a 12-point decrease is clinically meaningful.
MeSH Terms
Acetylcholine Release Inhibitors; Adult; Botulinum Toxins, Type A; Female; Humans; Male; Minimal Clinically Important Difference; Outcome Assessment, Health Care; Severity of Illness Index; Torticollis