Case-control or observational studies with at least 10 Parkinson's disease patients, aged over 18 years, with Parkinson's disease of any duration, treated with dopamine agonists, were eligible for inclusion. Case reports of fibrosis, valvular heart disease or valvulopathy without a control group were excluded. Eligible studies assessed the incidence, odds or risk of fibrosis, valvular heart disease or cardiac valvulopathy, as confirmed by echocardiography. Included outcomes comprised: aortic valve regurgitation; mitral valve regurgitation; tricuspid valve regurgitation; or total valve regurgitation.
The ergot-derived dopamine agonist interventions in the included studies were pergolide (0.71 to 3.2 mg/day), cabergoline (3.6 to 4.0 mg/day), and bromocriptine (8.5 mg/day). The other dopamine agonist interventions in the included studies were ropinirole (8.4 to 14.3 mg/day) and pramipexole (1.7 to 3.0 mg/day). These were compared with a control group untreated with a dopamine agonist or treated with a different agonist.
The mean age of patients in the included studies ranged from 55.0 to 73.5 years, mean duration of Parkinson's disease (where stated) was 5.0 to 11.2 years, and the proportion of males was between 30 and 88%. In one study, 64% of patients were receiving treatment for restless legs syndrome rather than Parkinson's disease.
The 'author group' selected studies for inclusion in the review, but it was not stated how many reviewers this comprised or how disagreements were resolved.