The schedule for the assessment of drug-induced movement disorders (SADIMoD): test-retest reliability and concurrent validity

The SADIMoD is a newly developed instrument, consisting of a compilation of rating scales, to measure the severity of drug-induced movement disorders: dystonia, dyskinesia, Parkinsonism, akathisia, ataxia, and several types of tremors. The test-retest reliability of this scale and the concurrent validity with the Abnormal Involuntary Movement Scale (AIMS), the Simpson-Angus Scale (SEE) and the Barnes Akathisia Scale (BAS) was assessed in 31 patients [20 male/11 female; 57.1 +/- 16.5 yr (mean +/- S.D.)] with a variety of movement disorders by six teams of investigators. The teams were trained by means of a standard package of instruction material to such an extent that a single member of the team could represent the entire team. Each patient was rated according to the AIMS, SEE and BAS and recorded on videotape according to the SADIMoD Schedule. These video-recordings were scored twice; first, in consensus by the entire team and secondly [110.3 +/- 58.0 d (mean +/- S.D.) later] by a single representative of that team. One team underwent a major change between scoring and was excluded from this analysis. Despite these difficult circumstances, these first and second ratings correlated to a highly significant degree with Spearman's correlation coefficients of 0.57 to 0.88 (median 0.69). The homogeneity of the applied scales was good (Cronbach's alpha = 0.75-0.94). Convergent validity was Found between the SADIMoD dyskinesia and (to a lesser extent) dystonia scales and the AIMS as well as between the akathisia sub-scales and the BAS, with divergent validity with the other sub-scales. The SEE discriminated less well between the Parkinsonism sub-scale and the other sub-scales.