Frequency of neuroleptic malignant syndrome in a large psychiatric hospital in Moscow.

A ten-year prospective survey of neuroleptic malignant syndrome (NMS) was performed in a major psychiatric hospital (1,510 beds) in Moscow. All inpatients who developed a persistent and severe extrapyramidal rigidity accompanied by fever after exposure to neuroleptic medication were screened for NMS. The diagnosis of NMS was established according to Levenson's criteria and at a later stage all NMS cases were reevaluated using the DSM-IV research criteria. Data on age, gender and psychiatric diagnoses were analyzed. Of the 78,708 inpatients treated with neuroleptic agents, 19 separate patients had an episode of NMS, for a frequency of 0.02%. Mortality rate was 10.5% (2/19 patients). Of the three potential risk factors studied, only young age (</= 25 years) was significantly associated with an increased frequency of NMS (P < 0. 01). The low rate of NMS found here compared to studies in other countries may be due to the stringent demands for NMS diagnosis. More large-scale prospective studies including detailed clinical and laboratory data are needed to clarify these differences and their impact on the prevalence and risk factors of NMS.