Incidence and risk factors of institutionalisation in Parkinson's disease and atypical parkinsonism

Introduction
The basic epidemiology of institutionalisation (the need for long-term care in an institution) in parkinsonism is unclear. We aimed to identify the incidence of, and risk factors for, institutionalisation in Parkinson's disease (PD) and atypical parkinsonism (AP).

Methods
We analysed data from a prospective population-based incidence cohort of parkinsonism in North-East Scotland (the PINE study). 556 newly-diagnosed participants (PD, N = 200; AP, N = 98; controls, N = 258), recruited between 2002 and 2009, were prospectively followed life-long with data collection on place of residence. We determined the incidence and baseline predictors of institutionalisation using Cox regression.

Results
The median follow-up time was 9.3, 4.4, and 10.8 years in PD, AP, and controls respectively. 70 (35 %) PD, 53 (54 %) AP, and 43 (16 %) controls became institutionalised. The incidence rates of institutionalisation in PD, AP, and controls were 5.1, 20.8, and 1.8 per 100 person-years respectively. The median time to institutionalisation was 11.8 years in PD and 3.5 years in AP. Multivariable Cox regression showed that AP (HR versus PD = 3.05 [95 % CI 1.90,4.91]), increasing age (HR for 10-year increase = 1.82 [95 % CI 1.40,2.36]), poorer cognition (HR for MMSE<24 versus MMSE>27 = 2.62 [95 % CI 1.45, 4.73]), more-severe parkinsonian impairment (UPDRS part 3) (HR for 10-point increase = 1.25 [95 % CI 1.05, 1.48]) were independently associated with higher hazards of institutionalisation. Sex, co-morbidity, smoking history, and living alone were not associated with institutionalisation.

Conclusion
Institutionalisation is much more frequent in parkinsonism, particularly in AP, than in controls. AP, older age, severe parkinsonian impairment, and poorer cognition were independent baseline predictors of institutionalisation.