Drug-associated extrapyramidal symptoms (EPS) in people with intellectual disability (ID) may be difficult to recognize, and clinicians' assessments may be hampered by lack of patients' capacities to adequately cooperate and by lack of reliable instruments to measure EPS in this population. Therefore, we compared assessments based on professional caregivers' observations with the informant-based validated Matson Evaluation of Drug Side Effects (MEDS) scale with assessments by clinicians using a set of clinical rating scales, most of which have not been validated for use in this population. We also compared 2 dyskinesia scales by replacing the widely used but not validated Abnormal Involuntary Movement Scale with the validated Dyskinesia Identification System Condensed User Scale (DISCUS) in half of the set of scales. We used linear regression to analyze associations between EPS as measured with MEDS and EPS as measured with the sets of scales at item and at scale level.
Of the 30 MEDS items, 6 were associated with items of the other scales. At scale level, we found no significant associations. Comparison of the Abnormal Involuntary Movement Scale with the DISCUS indicated that the DISCUS may be preferable for use in people with ID.
Results may be explained by shortcomings in education and training of caregivers and by lack of reliable assessments and rating scales for EPS in people with ID.
We conclude that there is an urgent need for education and training of care professionals and clinicians in this area and for studies investigating the psychometric properties of rating scales.