A Cocrane review [Abstract] 1 included 19 trials with 19 different randomised dose comparisons. It aimed to determine the best range of doses for haloperidol for the treatment of people acutely ill with schizophrenia. Most studies were between 3 and 6 weeks. The most common comparison was standard higher dose (>7.5 to 15 mg/day) vs. high dose (>15 to 35 mg/day). No studies reported data on relapse rates or quality of life and only one compared low dose (>1.5 to 3 mg/day) haloperidol to higher dose ranges. Using standard lower dose (>3 to 7.5 mg/day) did not result in loss of efficacy (no clinically important improvement in global state vs. standard higher dose (>7.5 to 15 mg/day, RR 1.09, 95% CI 0.7 to 1.8; 1 RCT, n = 48) or vs. high dose (>15 to 35 mg/day, RR 0.95, 95% CI 0.8 to 1.2; 2 RCTs, n=81)). Doses of haloperidol in the range of >3 to 7.5 mg/day had a lower rate of development of clinically significant extrapyramidal adverse effects (AEs) than higher doses (clinically significant extrapyramidal AEs, vs. standard higher dose: RR 0.12, 95% CI 0.01 to 2.1; 2 RCTs, n = 64; vs. high dose RR 0.59, 95% CI 0.5 to 0.8; 3 RCTs, n=144); vs. very high dose (>35 mg/day, RR 0.70, 95% CI 0.5 to 1.1; 2 RCTs, n = 86). None of the other comparisons between dose ranges yielded statistically significant differences, but several, particularly with lower dose ranges, were underpowered to detect clinically meaningful differences.
Comment: The quality of evidence is downgraded by study quality (unclear allocation concealment) and imprecise results (few small trials for each comparison).
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