A Cochrane review [Abstract] 1 included 13 RCTs with a total of 478 patients with neuroleptic-induced tardive dyskinesia (TD). Most studies were of short duration (less than 13 weeks) but 4 had a follow-up period longer than 5 months. The patients were mostly men in their 50s, with diagnoses of various chronic psychiatric disorders, but mainly schizophrenia. There was no clear difference between vitamin E and placebo for the outcome of 'clinically relevant improvement in TD' (RR 0.95, CI 0.89 to 1.01; 6 trials, n=264). For the outcome of 'any improvement in TD symptoms', there was no clear difference between the groups, either (RR 0.87, CI 0.76 to 1.00; 7 trials, n=319). However, people allocated to placebo showed more deterioration of their symptoms compared with those given vitamin E (RR 0.23, CI 0.07 to 0.6; 5 trials, n=85). There was no difference in the incidence of adverse effects (RR 1.21, CI 0.35 to 4.15; 9 trials, n=205), extrapyramidal adverse effects (MD 1.10, 95% CI -1.02 to 3.22; 1 RCT, n = 104), or leaving the study early (RR 1.29, CI 0.72 to 2.3; medium term 8 trials, n=232). There is no trial-based information regarding the effect of vitamin E for those with early onset of TD.
Comment: The quality of the evidence is downgraded by study quality (inadequate allocation concealment), imprecise results (small trials) and indirectness of evidence (short follow-up).
Primary/Secondary Keywords