THE BLEPHAROSPASM DISABILITY SCALE - AN INSTRUMENT FOR THE ASSESSMENTOF FUNCTIONAL HEALTH IN BLEPHAROSPASM

Assessment of the functional status in patients with blepharospasm is of major importance for clinical practice and outcome studies. The Ble pharospasm Disability Scale (BDS) is specifically directed to measure the disability in these patients. The metric properties of this instru ment were evaluated. Reliability, validity, and responsiveness to with in-patient health changes over time of the BDS were assessed in 40 pat ients with essential blepharospasm treated with botulinum toxin inject ions. The reliability of the scale was sufficient for use on group lev el (Cronbach's alpha coefficient, 0.69). Evidence of discriminant vali dity was provided by the difference in median score on the BDS between 21 newly admitted patients and 19 patients already under treatment (p < 0.001). Convergent validity was supported by correlations between B DS and neurological impairment scores (range, Spearman correlation coe fficients, 0.65-0.79). Responsiveness to health changes was demonstrat ed by a significant difference between median BDS scores before treatm ent and 2 weeks after treatment with botulinum toxin (p < 0.01). The B DS is a useful disease-specific instrument to assess disability. Compl etion of the questionnaire is easy and takes only a few minutes. The i nstrument is suitable for use in patient care, descriptive outcome stu dies, and should be considered in controlled clinical trials.