Functional Impairment in Individuals With Prodromal or Unrecognized Parkinson Disease

IMPORTANCE Daily functioning in individuals with prodromal Parkinson disease requires more detailed description.OBJECTIVE To evaluate whether functional limitations exist in individuals with Parkinson disease prior to diagnosis compared with the general population.DESIGN, SETTING, AND PARTICIPANTS This case-control study used Medicare-linked data from the National Health and Aging Trends Study (NHATS), a longitudinal survey in the US, for a random subsample of Medicare beneficiaries aged 65 years or older, with Black and older individuals oversampled by design. Patients with incident Parkinson disease were defined as having 2 or more Medicare diagnoses from January 2011 to December 2017, with Medicare eligibility 2 or more consecutive years prior to the first diagnosis. Controls were defined as individuals with Medicare eligibility at a baseline year and 2 or more years prior, with no Parkinson disease diagnosis. Analyses were conducted from November 2021 to June 2022.EXPOSURES Responses to survey questions addressing dexterity, eating, mobility, mood, pain, sleep, speech, strength, and vision.MAIN OUTCOME AND MEASURES Associations between survey responses and Parkinson disease diagnosis in the first year of diagnosis (baseline) and up to 3 years prior to diagnosis (ie, during the prodromal phase) were examined using logistic regression.RESULTS A total of 6674 participants were included. The participant numbers and case prevalence each year varied from 3492 to 5049 and from 700 to 1180 per 100 000 population, respectively. The median age groups were 75 to 79 years and 80 to 84 years, and the percentage of females varied from 48.21% (27 of 56 cases) to 59.98% (2079 of 3466 controls) across all years, with similar proportions among cases and controls. Individuals with prodromal Parkinson disease were less likely to report being able to walk 6 blocks (odds ratio [OR], 0.34; 95% CI, 0.15-0.82), stand independently from a kneeling position (OR, 0.30; 95% CI, 0.11-0.85), or lift a heavy object above one's head (OR, 0.36; 95% CI, 0.15-0.87) and were more likely to report imbalance (OR, 2.77; 95% CI, 1.24-6.20) 3 years prior to diagnosis.CONCLUSIONS AND RELEVANCE The findings suggest that individuals with prodromal or unrecognized Parkinson disease may have greater impairment in activities involving mobility and strength up to 3 years prior to diagnosis compared with the general population. Identification of prodromal disease may facilitate earlier intervention to improve function.