Clinimetric testing of the comprehensive cervical dystonia rating scale

Abstract

Objective To test the clinimetric properties of the Comprehensive Cervical Dystonia Rating Scale. Background This is a modular scale with modifications of the Toronto Western Spasmodic Torticollis Rating Scale (composed of three subscales assessing motor severity, disability and pain) now referred to as the revised Toronto Western Spasmodic Torticollis Scale-2.; a newly developed psychiatric screening instrument; and the Cervical Dystonia Impact Profile-58 as a quality of life measure. Methods Ten dystonia experts rated subjects with cervical dystonia using the comprehensive scale. Clinimetric techniques assessed each module of the scale for reliability, item correlation and factor structure. Results There were 208 cervical dystonia patients (73% women, age 59±10 years, duration 15±12 years). The internal consistency of the motor severity subscale was acceptable (Cronbach’s alpha = 0.57). Item to total correlations showed that elimination of items with low correlations (<0.20) increased alpha to 0.71. Internal consistency estimates for the subscales for disability and pain were 0.88 and 0.95 respectively. The psychiatric screening scale had a Cronbach’s alpha of 0.84 and satisfactory item to total correlations. When the subscales of the Toronto Western Spasmodic Torticollis scale -2 were combined with the psychiatric screening scale, Cronbach's alpha was 0.88, and construct validity assessment demonstrated four rational factors: motor, disability, pain and psychiatric disorders. The Cervical Dystonia Impact Profile-58 had an alpha of 0.98 and its construction was validated through a confirmatory factor analysis. Conclusions The modules of the Comprehensive Cervical Dystonia Rating Scale are internally consistent with a logical factor structure.

Development and Validation of a Disease-Specific Oromandibular Dystonia Rating Scale (OMDRS)

“…However, if the items are negatively associated within a subscale, the subscale cannot reach sufficient internal consistency as assessed by Cronbach's alpha (12). Comella et al deleted such items from the motor severity subscales when they developed the CCDRS (19). In contrast, in this study, only the severity subscale (four items) was assigned five patterns according to the subtypes of oromandibular dystonia (jaw closing, tongue, jaw opening, jaw deviation [protrusion], and lip dystonia) (Appendix).…”

“…However, the Movement Disorders Society Task Force on dystonia rating scales did not recommend the OMDQ-25, but merely suggested it, because it was only used by the original developers and not by other researchers (14). The development and validation of rating scales for dystonia (13,(17)(18)(19) and Parkinson's disease (19)(20)(21) have been completed through multicenter studies at several university hospitals or movement disorder centers with interdisciplinary teams in dystonia, neurology, psychiatry, clinimetrics, and biostatics. However, since there are no hospitals or departments that specialize in oromandibular dystonia in Japan or other countries, the development and validation of the OMDRS were conducted by an oromandibular dystonia specialist.…”

“…The oromandibular dystonia rating scale (OMDRS) was developed and confirmed to be reliable and valid based not only on standard methods for health measurement scales (12,16) but also on methods for creating scales for oromandibular dystonia (11), craniocervical dystonia (13,(17)(18)(19), and Parkinson's disease (20)(21)(22). The classical test theory comprises a series of principles that allow physicians to determine the efficacy of appropriate proxy indicators for estimating unobservable variables (16).…”

“…Redundancy was assessed by items loading multiple factors (19). If an item had multiple clinimetric failures, such as poor item-to-total correlation (defined as ≤ 0.3), poor factor loading (defined as ≤ 0.4), or a skewness out of the range of −1.50 to +1.50 representing possible ceiling or floor effects, it was omitted from the scale (12,19). Of the original 42 items, 14 were deleted because of low internal consistency with the other items or redundancy within a subscale.…”

Quality of life outcomes after deep brain stimulation in dystonia: A systematic review

“…SF-36 or EQ-5D) presumably because of a lack of disease-specific HRQoL measures in these populations. For patients with cervical dystonia, the combination of the TWSTRS-2 and Cervical Dystonia Impact Profile-58 were validated as a rating scale covering the aspects of motor, disability, pain, psychiatric problems, and HRQoL [78]. Similar comprehensive scales are needed for the other subtypes of dystonia.…”