Longitudinal analysis of impulse control disorders in Parkinson disease

Objective To investigate the longitudinal dose-effect relationship between dopamine replacement therapy and impulse control disorders (ICDs) in Parkinson disease (PD). Methods We used data from a multicenter longitudinal cohort of consecutive patients with PD with <= 5 years' disease duration at baseline followed up annually up to 5 years. ICDs were evaluated during face-to-face semistructured interviews with movement disorder specialists. Generalized estimating equations and Poisson models with robust variance were used to study the association between several timedependent definitions of dopamine agonist (DA) use, taking dose and duration of treatment into account, and ICDs at each visit. Other antiparkinsonian drugs were also examined. Results Among 411 patients (40.6% women, mean age 62.3 years, average follow-up 3.3 years, SD 1.7 years), 356 (86.6%) took a DA at least once since disease onset. In 306 patients without ICDs at baseline, the 5-year cumulative incidence of ICDs was 46.1% (95% confidence interval [CI] 37.4-55.7, DA ever users 51.5% [95% CI 41.8-62.1], DA never users 12.4% [95% CI 4.8-30.0]). ICD prevalence increased from 19.7% at baseline to 32.8% after 5 years. ICDs were associated with ever DA use (prevalence ratio 4.23, 95% CI 1.78-10.09). Lifetime average daily dose and duration of treatment were independently associated with ICDs with significant dose-effect relationships. Similar analyses for levodopa were not in favor of a strong association. ICDs progressively resolved after DA discontinuation. Conclusion In this longitudinal study of patients with PD characterized by a high prevalence of DA treatment, the 5-year cumulative incidence of ICDs was approximate to 46%. ICDs were strongly associated with DA use with a dose-effect relationship; both increasing duration and dose were associated with ICDs. ICDs progressively resolved after DA discontinuation.