Adherence to istradefylline in patients with Parkinson's disease: A group-based trajectory analysis

Understanding the different patterns of adherence to istradefylline treatment is essential to identifying Parkinson's disease (PD) patients who might benefit from targeted interventions. This descriptive study aimed to identify longitudinal istradefylline adherence patterns and to characterize factors associated with them. We identified PD patients aged 21–99 years who initiated istradefylline treatment in a Japanese hospital administrative database. Group-based trajectory modeling was used to model the monthly proportion of days covered over time to identify distinct 360-day adherence patterns. Factors associated with each adherence pattern were assessed using univariable multinomial logistic regression models. Of 2088 eligible PD patients, 4 distinct adherence groups were identified: consistently high adherence (56.8%); rapidly declining adherence (25.8%); gradually declining adherence (8.5%); and gradually declining and then recovering adherence (9.0%). Compared to the consistently high adherence group, the other groups had the following characteristics associated with a likelihood of lower adherence: the rapidly declining adherence group received fewer dopamine agonists (63.8% vs. 69.4%), monoamine oxidase B (MAO-B) inhibitors (26.8% vs. 31.6%), and catechol-O-methyl transferase inhibitors (31.6% vs. 37.0%) and had a higher prevalence of anxiety/mood disorders (29.9% vs. 24.6%); the gradually declining adherence group received fewer MAO-B inhibitors (22.5% vs. 31.6%) and amantadine (8.4% vs. 16.1%) and had a higher prevalence of mild cognitive impairment/dementia (27.0% vs. 18.8%); and the declining and then recovering adherence group had a higher prevalence of anxiety/mood disorders (34.2% vs. 24.6%). Clinicians should be aware of the heterogeneous patterns of adherence to istradefylline. •Our longitudinal descriptive study included PD patients starting istradefylline.•Group-based trajectory analysis identified 4 adherence groups of istradefylline.•Patient characteristics differed significantly among adherence groups.•Clinicians need to understand the heterogeneity of istradefylline adherence.