Mirapex (pramipexole) improved the quality of life for people with Parkinson’s disease compared to a placebo, according to a pooled analysis of several clinical trials.
Quality of life improvements were seen regardless of disease stage, duration of treatment, or quality of life assessments before treatment.
This analysis provided new evidence forMirapex’s potential treatment benefit in improving the quality of life in Parkinson’s patients, the researchers noted, adding their findings should be confirmed in larger trials with quality of life as a primary efficacy outcome.
The review study, “Efficacy of pramipexole on quality of life in patients with Parkinson’s disease: a systematic review and meta-analysis,” was published in BMC Neurology.
In Parkinson’s disease, abnormally low levels of dopamine, the nerve cell signaling molecule, lead to a progressive loss of control over body movements.
Mirapex, by Boehringer Ingelheim, is part of a class of medications called dopamine agonists, which mimic dopamine’s effect by binding to its receptors. Alone or combined with levodopa, a dopamine precursor, Mirapex prevents or delays motor decline and the involuntary, erratic movements (dyskinesia) associated with long-term levodopa use.
Attempts to investigate the impact of dopamine agonists such as Mirapex on quality of life (QoL) have been inconclusive due to differences in study design and QoL outcome measures, however.
Pooling quality of life analyses
In this context, one approach to determine Mirapex’s effect on QoL is to pool and analyze data from multiple placebo-controlled clinical trials that used consistent QoL outcome measures.
This method, referred to as a systematic review and meta-analysis, was applied by researchers at the First Affiliated Hospital of Dalian Medical University, China with scientists at Boehringer, who sponsored the study.
The team searched the medical literature for randomized, placebo-controlled clinical trials (RCTs) with Parkinson’s patients in any disease stage, regardless of age, sex, location, and race, wherein participants received Mirapex alone or in combination with other Parkinson’s therapies.
Eligible studies included those that measured QoL using the 39-item Parkinson’s disease questionnaire (PDQ-39) — the most widely used Parkinson’s-specific health-related QoL questionnaire. Lower scores indicate improved QoL.
Six studies were selected that included a total of at least 2,000 participants. Among them, four enrolled early Parkinson’s patients, while two involved those with advanced Parkinson’s. Participants who were randomly assigned Mirapex received 0.375–4.5 mg daily, with treatment duration ranging from three to nine months.
The mean change in PDQ-39 total score, from before treatment (baseline) to the last available data point, was extracted and pooled from all the trials except one, which reported a median PDQ-39 change.
All the studies showed reduced mean total PDQ-39 scores, ranging from -5.00 to -1.00 (higher scores reflect poorer quality of life). Compared to a placebo, pooled data demonstrated a significant mean change of –2.49 from baseline in PDQ-39 total score with Mirapex.
The heterogeneity, an estimate of the variability in this meta-analysis explained by differences between the selected trials, was low.
The team then explored Mirapex’s effects on QoL according to dose, as well as disease stage and PDQ-39 total score at baseline.
In five studies, Mirapex significantly improved QoL over a placebo with optimal doses of 1.5 mg prescribed to 80% or more participants (mean PDQ-39 difference of –2.65). No differences were seen for those who received low doses.
Mirapex significantly boosted QoL in patients with early Parkinson’s (mean PDQ-39 difference of –2.14) and those with advanced Parkinson’s (mean PDQ-39 difference of –3.95) over a placebo.
The team also found significant QoL improvements among participants with higher (worse) PDQ-39 scores at baseline (mean PDQ-39 difference of –3.89). Similar results were seen in those with lower (better) PDQ-39 scores at baseline (mean PDQ-39 difference of –2.04).
In studies with a shorter treatment duration of 18 weeks or less, Mirapex significantly enhanced QoL (mean difference of –2.88), as it did in studies with more than 18 weeks of treatment (mean difference of –2.26).
Excluding studies that may have had selective reporting bias and median values reported instead of mean did not alter the main findings.
An assessment of bias across the six selected studies was rated as acceptable due to proper study design. Only one study carried a potential risk for selective reporting because the authors did not adequately discuss missing data.
“Analysis of these six trials found a significant improvement in PDQ-39 total score with [Mirapex] compared with placebo,” the researchers wrote. “This meta-analysis provides new evidence for the potential treatment benefit of [Mirapex] in improving quality of life in patients with Parkinson’s disease.
“These results could be confirmed in larger [Mirapex] RCTs that investigate QoL as a major efficacy outcome of interest,” they said.
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