Drug-induced Parkinsonism: A strong predictor of idiopathic Parkinson's disease

Background Although Idiopathic Parkinson's disease (IPD) develops in considerable patients with drug-induced Parkinsonism (DIP), the association hasn't been well defined. We aimed to evaluate the underlying association and risk factors of DIP and IPD. Methods A retrospective cohort study using National Health Insurance Claims data in 2011-2016 was conducted. New-onset DIP patients in 2012 were selected and matched with active controls having diabetes mellitus at a 1:4 ratio by age, sex, and Charlson's Comorbidity Index score. Comorbidity, causative drugs, and prescription days were evaluated as covariates. Results A total of 441 DIP were selected. During the 4-year follow up, 14 IPD events in the DM group but 62 events in the DIP group were observed (adjusted hazard ratio, HR: 18.88, 95% CI, 9.09-39.22, adjusting for comorbidities and causative drugs). IPD diagnosis in DIP was observed high in males compared to females (15.58/13.24%). The event was the most within the 1(st) year follow-up, mean days 453 (SD 413.36). Subgroup analysis in DIP showed calcium channel blocker (verapamil, diltiazem, and flunarizine) was significantly associated with increased IPD risk (HR: 2.24, 95% CI, 1.27-3.93). Conclusion Increased IPD in DIP patients might not be from the causal toxicity of antidopaminergic effects but from a trigger by the causative drugs on the DIP patients who already had subclinical IPD pathology. DIP can serve as a strong proxy for IPD incidence. Subjects who develop DIP should be monitored carefully for potential IPD incidence.

Automated summary

Although Idiopathic Parkinson's disease (IPD) develops in considerable patients with drug-induced Parkinsonism (DIP), the association between the two has not been well defined. A retrospective cohort study using National Health Insurance Claims data in 2011-2016 was conducted to evaluate the underlying association and risk factors of DIP and IPD. The study found that increased IPD in DIP patients may be triggered by the causative drugs on the DIP patients who already had subclinical IPD pathology, and DIP can serve as a strong proxy for IPD incidence. Patients who develop DIP should be carefully monitored for potential IPD incidence.