Prevalence of and risk factors for respiratory dyskinesia

We explored the prevalence of respiratory dyskinesia (RD), diagnosed objectively using a spirograph, and the major risk factors for tardive dyskinesia (TD) and RD. A total of 258 inpatients treated with neuroleptics was interviewed, and TD was evaluated using the Abnormal Involuntary Movement Scale (AIMS). Movement of the chest and respiratory regularity were assessed on clinical examination. Spirographs of patients with suspected RD were recorded, and RD was diagnosed based on spirographic data and the concurrence of two investigators. The prevalence of TD in this study was 22.1% (57 of 258). Aging and organic brain damage (OBD) were confirmed as risk factors; female gender, mood disorders, and the duration of neuroleptic exposure were not. Ten of 28 patients suspected of having RD were diagnosed with RD on the basis of persistent respiratory irregularities without other physiologic causes. The overall prevalence of RD was 3.9% (10 of 258) and was 17.5% (10 of 57) among the TD patient population. Four of these patients complained of dyspnea, and three demonstrated grunting. RD was more highly associated with aging and OBD than with TD itself. The identification of risk factors for RD is not only helpful in planning prophylactic strategies, but also facilitates the understanding of the pathogenesis of this syndrome.