Systematic review of the effect of dopamine receptor agonists on patient health-related quality of life

Dopamine receptor agonists have demonstrated effectiveness in managing Parkinson's disease both as monotherapy and as adjunctive treatment to l-dopa. Dopamine receptor agonist therapy may reduce the risk of developing motor complications; however, it can also produce undesirable side-effects. Patient health-related quality of life (HRQoL) is a comprehensive outcome that may be useful in evaluating these complex effects. This is a systematic review of the reported clinical trials that have investigated the effect of dopamine receptor agonists on HRQoL.A literature search was carried out using Medline, cut-off date 30 June 2009. Identified manuscripts were classified according to level of evidence; Level I studies were rated for quality; relative change (RC) and effect size (ES) were calculated when possible; and dopamine receptor agonist efficacy in improving HRQoL was assigned accordingly.Overall, 18 manuscripts reporting clinical trial outcomes on seven dopamine receptor agonists were reviewed. Six studies were randomized and double-blinded; five were controlled with placebo; and 10 were comparative. Sample sizes ranged from 4 to 506 patients (mean, 181.1 ± 143.7), and follow-up ranged from 1.5 to 48 months (11.8 ± 14.2).Level I was reached by six of eight pramipexole studies (mean quality, 79%), one of four cabergoline studies (quality, 83.3%), and one study with the following: ropinirole prolonged release (quality, 88.9%), pergolide (quality, 86.0%), and rotigotine (quality, 77.8%). Quantifying HRQoL improvement by RC and ES was only possible for five of the 18 studies.The reviewed trials were highly variable in design, objectives and presentation of results. Therefore, specific evaluation of intervention impact in each of the tested clinical settings was required.