Parkinson’s disease case ascertainment in a large prospective cohort

Abstract

Background In epidemiologic studies where physician-based case adjudication is not feasible, Parkinson’s disease (PD) case ascertainment is often limited to self-reports which may not be accurate. We evaluated strategies to identify PD cases in the Agricultural Health Study (AHS). Methods Doctor-diagnosed PD was self-reported on all cohort-wide surveys; potential cases were also identified from death certificates. Follow-up surveys asked about PD-related motor and non-motor symptoms. For PD confirmation, we collected additional diagnosis, symptom, and treatment data from 510 potential PD cases or their proxy (65% of those contacted) in a supplemental screener and obtained medical records for a subset (n = 65). We classified PD cases using established criteria and screener data. Results Of 510 potential PD cases, 75% were considered “probable” or “possible”; this proportion increased among participants diagnosed by a specialist (81.2%), taking PD medication (85.2%), or reporting ≥5 motor symptoms (86.8%) in a regular AHS survey. Of those with medical records, 93% (57 of 61) of probable or possible PD was confirmed. Never-smoking and non-motor and motor symptoms reported in prior AHS surveys were more common with probable/possible PD than unconfirmed PD. Conclusion In this retrospective PD case ascertainment effort, we found that PD self-report with information on motor symptoms or medications may be a reasonable alternative for identifying PD cases when physician exam is not feasible. Because of intervening mortality, screeners could not be obtained from about one-third of those contacted. Thus, findings warrant replication.

Parkinson’s Disease Case Ascertainment in the Sister Study: A Cohort for Environmental Health Research

“…This often requires sequential clinical visits to neurology specialists, which are almost infeasible to implement in large population-based cohorts. With few exceptions [39,40], investigators often seek alternative approaches to cost-efficiently identify and confirm PD cases, for example, adjudication of selfreported diagnosis with additional diagnostic data collection from potential patients and their treating physicians [5,20,23,41,42], solely based on routine cohort data collection (e.g., self-reports, medication uses, hospitalization/death surveillances) [19,21], or via linkage to administrative data and electronic medical records [22].…”

“…However, most of these studies are large, not designed to study PD [15][16][17][18], and dependent on mailed surveys, phone interviews, or time-strained clinical visits for data collection, making study-based clinical exams for PD diagnosis infeasible. Often, alternative approaches were taken for field feasibility [5,[19][20][21][22][23]. Further, there is an apparent sex disparity in PD research with fewer and less robust nongenetic findings in women [15,[24][25][26].…”