A Cochrane review [Abstract] 1 included 6 studies with a total of 850 subjects.The trials were of low methodological quality and too heterogeneous to be pooled for meta-analysis. Only two trials were double-blind. The occurrence of dyskinesias in three short trials was too low to draw any conclusion. The results of the longer trials indicated a lower occurrence of dyskinesias in the bromocriptine tier. Dystonia occurred less frequently in the bromicriptine tier in the five trials that evaluated dystonia. However, for both dyskinesias and dystonia a statistically significant difference in favour of bromocriptine emerged only in the largest trial. There was a trend for less frequent wearing-off and on-off fluctuations in the bromocriptine group. Only the largest trial reported more improvement of impairment in the levodopa group than in the bromocriptine group. The rest of the trials showed no difference. A statistically larger number of dropouts occurred in the bromocriptine group because of inadequate response or intolerable side effects.
Comment: The quality of evidence is downgraded by study quality (inadequate allocation concealment) and inconsistency (heterogeneity in follow-up time, measurements and outcomes).
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