Reply to ‘Comment on Martino et al. ‘Scales for Antipsychotic-Associated Movement Disorders: Systematic Review, Critique, and Recommendations’”

Abstract

We thank Professor Loonen for the attention given to our article and the detailed critique. Movement disorders associated with antipsychotic drug exposure are among the most common conditions referred to movement disorders specialists, both in outpatient and inpatient settings. Hence, our subcommittee approached this work with longstanding clinical experience of the challenges in assessing these symptoms. Unlike what Loonen states, our article does not suggest replacing the term “dyskinesia” with “stereotypy” but, rather, to introduce in the nomenclature terms that indicate well-defined hyperkinetic phenomena. At present, “dyskinesia” is often used as a passepartout word that may encompass different phenomena, including stereotypies. Supporting the occurrence of new-onset antipsychoticassociated movement disorders in clinical trials, a proportion of which occur acutely, an overview and meta-analysis of Cochrane reviews that focused on acute parkinsonism, dystonia, akathisia, and tremor yielded, respectively, upper limits of prevalence estimate ranges of 29%, 15%, 16%, and 28%. As stated by Loonen, acute antipsychotic-associated dystonia and other movement disorders require rapid intervention. Rather than minimizing the need for rating instruments applicable also to acute movement disorders, the need for rapid treatment corroborates it. Furthermore, even if for some movement disorders (eg, akathisia) acute and tardive counterparts are phenomenologically similar, the need to intervene rapidly justifies swift and efficient rating of acute forms through the adaptation of preexisting instruments or even the development of new instruments. We were surprised to read Professor Loonen’s concerns around the quality of article selection. Both publications on the validation study of the Schedule for the Assessment of Drug-Induced Movement Disorders (SADIMoD) as well as the study by Knol and colleagues were cited in the supplementary file of our article (see references 73, 74, and 64 in that document), which contains a detailed analysis of each rating instrument. The criteria for recommendations that we used are those adopted in several publications commissioned by the International Parkinson and Movement Disorder Society Clinical Outcome Assessments Scientific Evaluation Committee. The “suggested” recommendation for the SADIMoD stems from its not having been applied by authors different from its developers, the length of administration, and some limitations of its psychometric profile. Regarding the comment on the Abnormal Involuntary Movements Scale, again we express clearly in the supplementary file that the total severity is conventionally the sum of the scores of items 1 to 7 and refer to the publication of supplementary instructions to score the first seven items. Its widespread use in psychiatric patients and acceptable psychometric properties justified our recommendation. We also agree on some important limitations, such as limited internal consistency and its being weighted toward facial dyskinesia, to which Professor Loonen’s pertinent suggestion to score dyskinesia severity separately during activity and at rest should indeed be added. Finally, we believe that the persisting divide in movement disorders nomenclature between neurologists and psychiatrists is both dangerously confusing and anachronistic. We were therefore glad to find Professor Loonen in agreement with our advocating for a collaborative effort of neurologists and psychiatrists in revising the nomenclature and classification of antipsychotic-associated movement disorders as well as in planning further psychometric work on existing rating instruments. In this collaborative spirit, we think that our systematic review and critique represents a consultation source that will aid future work to harmonize the screening and assessment of antipsychotic-associated movement disorders.