Thirteen RCTs (n=2,163) were included in the review.
No significant statistical heterogeneity was found for any of the meta-analyses of pramipexole and ropinorole combined versus levodopa or placebo (P>0.05).
Comparisons versus levodopa.
Compared with levodopa, pramipexole and ropinirole combined significantly increased the risk of somnolence (RR 1.61, 95% CI: 1.21, 2.13) and hallucinations (RR 1.92, 95% CI: 1.08, 3.43). There was no statistically significant difference between pramipexole and ropinirole combined and levodopa for dizziness, nausea or hypotension.
In 3 RCTs (n=463) of ropinirole compared with levodopa, ropinirole significantly increased hallucinations (RR 2.25, 95% CI: 1.16, 4.36) and somnolence (RR 1.57, 95% CI: 1.04, 2.37). There was no significant difference between ropinirole and levodopa for hypotension, dizziness or nausea.
In 4 RCTs (n=596) of pramipexole compared with levodopa, there was no significant difference between the two treatments for any of the specified adverse effects.
Comparisons versus placebo.
Compared with placebo, pramipexole and ropinirole combined significantly increased the risk of hypotension (RR 2.14, 95% CI: 1.02, 4.48), somnolence (RR 3.16, 95% CI: 1.62, 6.13), hallucination (RR 4.24, 95% CI: 1.87, 9.62), dizziness (RR 1.60, 95% CI: 1.17, 2.20) and nausea (RR 2.15, 95% CI: 1.69, 2.75).
In 3 RCTs (n=451) of ropinirole compared with placebo, ropinirole significantly increased the risk of hypotension (RR 6.46, 95% CI: 1.47, 28.28), dizziness (RR 2.04, 95% CI: 1.38, 3.07), nausea (RR 2.93, 95% CI: 1.66, 5.17) and somnolence (RR 5.73, 95% CI: 2.34, 14.01). There was no significant difference between ropinirole and placebo for hallucinations.
In 3 RCTs (n=653) of pramipexole compared with placebo, pramipexole significantly increased nausea (RR 1.83, 95% CI: 1.34, 2.50), somnolence (RR 2.01, 95% CI: 2.17, 3.16) and hallucinations (RR 5.20, 95% CI: 1.97, 13.72). There was no significant difference between pramipexole and placebo for hypotension or dizziness.