Association of Visit Frequency and Income with Parkinson’s Disease Progression: A Cohort Study

Background

Continuous medical management is essential in Parkinson’s disease (PD); however, the impact of visit frequency and socioeconomic status on disease progression remains unclear. This study examined the associations of visit frequency and income status with PD progression.

Methods

We conducted a retrospective cohort study using the National Database (NDB) of Japan. The study population consisted of patients with mild PD who underwent the 2015 specific health checkup and had not received PD designated intractable disease certification at baseline. PD progression was defined as the first certification of PD as a designated intractable disease. Participants were followed for up to 8 years. Income status was classified into general/high-income and low-income groups based on copayment categories. Visit frequency before progression was categorized as high (≥1 visit every 2 months) or low. Covariates included sex, age category, and PD duration. Kaplan–Meier analysis and Cox proportional hazards models were used. Interaction and time-varying effects were also examined.

Results

Among 1,701 patients, 884 developed PD progression. Kaplan–Meier curves showed higher cumulative incidence in the high-frequency group (log-rank p < 0.001). In the fully adjusted Cox model, high visit frequency was associated with increased risk of progression (HR 3.67, 95% CI 2.93–4.59). The main effect of income was not significant, but a significant interaction between income and visit frequency was observed (HR 0.46, 95% CI 0.29–0.71). Time-varying analysis showed that the effect of income increased after 36 months.

Conclusions

Visit frequency was strongly associated with PD progression, and the effect of income depended on visit frequency and follow-up time. These findings suggest the importance of considering the interaction between healthcare utilization and socioeconomic factors. Reverse causation cannot be excluded.

Key messages

• This study reveals that visit frequency is strongly linked to Parkinson’s progression, and this effect is significantly modulated by patients’ income status over long-term follow-up.

• Our findings highlight that socioeconomic factors interact with healthcare utilization in PD, suggesting that interventions must address social determinants to improve clinical outcomes.