Parkinson's disease patients first treated at age 75 years or older: Acomparative study

Background: Parkinson's disease (PD) first diagnosed at older age reportedly has different clinical characteristics and survival rates than when it is first diagnosed at younger age. We compared these features among PD patients who initiated anti-parkinsonian drugs at age 75-85 years (elderly) with those who started treatment at age 50-74 years (younger). Methods: We used a population-based cohort of 4449 incident cases of PD patients aged 50-85 at treatment initiation, based on a pharmacy registry of Maccabi Health Maintenance Organization, with definite/probable/possible certainty of having PD. Mean follow-up was 3.9±2.6 years. The two age groups were compared for time/risk to levodopa and to death, using Kaplan-Meier curves and Cox regression. Gender-specific standardized mortality rates (SMRs) accounting for Israeli death rates were also compared. Results: One-half of the entire cohort (n=2148) were elderly (>75 years) and more likely to be given levodopa (Hazard Rate (HR)=1.48, P<0.05), had a significantly higher frequency of comorbidities (e.g.,heart disease, hypertension and cancer), and had a 3-fold increased risk to die (HR=2.97, P<0.05) within the same follow-up time as the youngers. Accounting for the general Israeli population death rates, female PD patients had a significantly lower risk to die compared to males especially females who were elderly at treatment initiation (SMR=1.53 for females vs. 1.73 for males, P<0.05). Conclusions: PD patients first diagnosed and treated at >74 years of age comprise a unique cluster for inclusion into drugs studies, mortality risk analyses and for projection of disease burden.