Predicting the long-term risk of tardive dyskinesia in outpatients maintained on neuroleptic medications.

BACKGROUND: Tardive dyskinesia (TD) has been a source of great concern to the psychiatric community because of the iatrogenic nature of the illness. Little is known about the risk of developing TD if neuroleptic medications are continued.
METHOD: This paper presents long-term risk estimates for TD in a prospective cohort study of 362 chronic psychiatric outpatients who were free of TD at baseline and who were maintained on neuroleptic medications.
RESULTS: On the basis of 5 years of follow-up, we estimate the risk of persistent TD to be 32% after 5 years of neuroleptic exposure (95% confidence interval [CI] = 23%-43%), 57% after 15 years of exposure (95% CI = 47%-66%), and 68% after 25 years of exposure (95% CI = 58%-77%). For patients with 10 years of previous neuroleptic exposure, the risk is 15% after 5 more years of exposure (95% CI = 7.2%-27%) and 38% after 15 more years of exposure (95% CI = 24%-53%). Our results fall within the wide range of results found in other studies of TD incidence. Differences in incidence across studies may be explained in terms of patient characteristics and other methodological factors.
CONCLUSION: One implication of this finding is that patients in the first 5 years of exposure could be targeted for prevention programs if resources are limited. A potential methodological problem encountered when studying chronically exposed patients is that they may have acquired TD (persistent) prior to the study and remitted before entry.