Objective: Few studies have followed Parkinson's disease (PD) patients from the time of diagnosis to the date of death. This study compared mortality in the Trondheim PD cohort to the general population, investigated causes of death and analyzed the associations between mortality and age at disease onset (AAO) and cognitive decline defined as Montreal Cognitive Assessment (MoCA) score below 26.
Methods: The cohort was followed longitudinally from 1997. By the end of January 2020, 587 patients had died. Comparisons to the Norwegian population were performed by calculating standardized mortality ratios (SMRs). Survival curves were estimated using the standard Kaplan-Meier estimator, and multivariable Cox proportional hazard models were estimated to investigate associations.
Results: SMR was 2.28 [95% confidence interval (CI): 2.13-2.44] for the whole cohort. For participants with AAO 20-39 years, the SMR was 5.55 (95% CI: 3.38-8.61). Median survival was 15 years (95% CI: 14.2-15.5) for the whole cohort. Early-onset PD (EOPD) patients (AAO < 50 years) had the longest median survival time. For all groups, there was a significant shortening in median survival time and an almost 3-fold higher age- and sex-adjusted hazard ratio for death when the MoCA score decreased below 26.
Conclusion: PD patients with an AAO before 40 years had a more than fivefold higher mortality rate compared to a similar general population. EOPD patients had the longest median survival; however, their life expectancy was reduced to a greater degree than that of late-onset PD patients. Cognitive impairment was strongly associated with mortality in PD.
Keywords: Cognitive impairment; Early- onset Parkinson’s disease; Mortality; genetic.