DEMOGRAPHIC FACTORS INFLUENCE PARTICIPATION IN LUMBAR PUNCTURES

Lumbar punctures (LP) and cerebrospinal fluid (CSF) collection are a crucial component of Alzheimer's disease (AD) prevention clinical trials. Changes in levels of biomarker proteins beta-amyloid and tau in CSF can indicate early stages of AD. In the Wisconsin Alzheimer's Disease Research Center (ADRC) Clinical Core, participation in longitudinal CSF collection was optional for all participants through September 2015. We investigated whether certain demographic factors influence a participant's likelihood to both participate in CSF collection at a baseline visit. Chi-square analyses and independent t-tests were used to evaluate each variable individually (ethnicity, gender, family history of AD, age, waist-to-hip [WHR] ratio, body mass index [BMI], and years of education [demographics in Table 1]. Logistic regression was conducted for the significant predictors age, years of education, family history, and BMI. Since participants from under-represented minority groups were not all approached for CSF collection, race was not included in this preliminary analysis. Additionally, this analysis does not yet include factors that may influence whether a participant commits to multiple LPs, such as adverse events and success of the first LP. Participants who are younger (p=0.01), have a family history of AD (p=0.007), more education (p=0.001) and a lower BMI (p<0.001) are more likely to agree to undergo an LP. Among all participants, BMI (OR=.97, [95%CI .946-.991], p=.006), years of education (OR=1.072, [95%CI 1.017-1.130], p=0.01), and age (OR=.99, [95%CI .972-1.0], p=0.05) were all significant predictors of LP participation. Among only participants with normal cognition, BMI was the only significant predictor (OR=.97, [95%CI .940-.993], p=.014). Body mass index, a possible proxy for overall general health, seemed to have the greatest impact on a participant's decision to participate in CSF collection. Understanding the factors that impact participation is critical so that education and recruitment efforts can be targeted more effectively. Future analyses will look for associations between a participant's race and likelihood of LP participation, as well as additional factors that may predict a participant's likelihood to undergo multiple LPs.