Supplementary Material for: The Extrapyramidal Symptom Rating Scale (ESRS) and its Abbreviated version (ESRS-A): A Critical Review of Clinimetric Properties

The Extrapyramidal Symptom Rating Scale Abbreviated (ESRS-A) is an abbreviated version of the Extrapyramidal Symptom Rating Scale (ESRS) with instructions, definitions, and a semi-structured interview that follows clinimetric concepts of measuring clinical symptoms. Similar to the ESRS, the ESRS-A was developed to assess four types of Drug-Induced Movement Disorders (DIMD): parkinsonism, akathisia, dystonia, and tardive dyskinesia (TD). The present review of the literature provides the most relevant clinimetric properties displayed by the ESRS and ESRS-A in clinical studies. Comprehensive ESRS-A definitions, official scale and basic instructions are provided. ESRS inter-rater reliability was evaluated in two pivotal studies and in multi-center international studies. Inter-rater reliability was high for assessing both antipsychotic-induced movement disorders and idiopathic Parkinson’s disease. Guidelines were also established for inter-rater reliability and the rater certification processes. The ESRS showed good concurrent validity with 96% agreement between Abnormal Involuntary Movement Scale (AIMS) for TD-defined cases and ESRS-defined cases. Similarly, concurrent validity for ESRS-A total and subscores for parkinsonism, akathisia, dystonia, and dyskinesia ranged from good to very good. The ESRS was particularly sensitive for detecting DIMD-related movement differences following treatment with placebo, antipsychotics, antiparkinsonian and antidyskinetic medications. ESRS measurement of drug-induced extrapyramidal symptoms was shown to discriminate extrapyramidal symptoms from psychiatric symptoms. The ESRS and ESRS-A are valid clinimetric indices for measuring drug-induced movement disorders. They can be valuably implemented in clinical research, particularly in trials testing antipsychotic medications, and in clinics to detect the presence, severity, and response to treatment of movement disorders.