A Cochrane review [Abstract] 1 included 4 RCTs with a total of 221 patients. Three of the trials were short-term and one long-term. All participants had schizophrenia that was treatment-resistant or presented with prominent negative symptoms. Most of the trials were conducted at hospitals. All studies compared sulpiride plus clozapine with clozapine (+/- placebo). Short-term data of 'no clinically significant response' in global state tended to favour sulpiride augmentation of clozapine compared with clozapine alone (RR 0.58, 95%CI 0.3 to 1.09; 3 RCTs, n=193). Sulpiride plus clozapine group had more movement disorders (RR 48.24, 95%CI 3.05 to 762.56; 1 RCT, n=70) and an increase in serum prolactin (skewed data, 1 RCT), but less incidence of hypersalivation (RR 0.49, 95%CI 0.29 to 0.83; 3 RCTs, n=162) and less weight gain (RR 0.30, 95% CI 0.09 to 0.99; 1 RCT, n=64). The augmentation of clozapine by sulpiride also caused less appetite loss (RR 0.09, 95%CI 0.01 to 0.70, NNT 4, 95% CI 4 to 12, Z=2.31, 1 RCT, n=70) and less abdominal distension (RR 0.10, 95% CI 0.01 to 0.78, NNT 5, 95%CI 4 to 19, Z=2.20, 1 RCT, n=70). Long-term data showed no significant difference in global state (RR 0.67, 95%CI 0.42 to 1.08; 1 RCT, n=70) and relapse (RR 0.85, 95%CI 0.5 to 1.3; 1 RCT, n=70).
Comment: The quality of evidence is downgraded by study quality (unclear allocation concealment), indirectness (differences in populations, short follow-up time) and imprecise results (limited study size for comparisons).
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