INTRODUCTON: Longitudinal prospective cohort studies are essential to understanding disease risk over time. Participant retention is critical to maintaining scientific validity, but participant attrition is a challenge and may vary by factors such as age, race/ethnicity, or sex. We examined response patterns over time in a large U.S. prospective cohort by various demographic factors.

AIM: The aim of this analysis was to examine the response patterns of CPS-3 participants across the three survey cycles, with a focus on how four socio demographic characteristics – gender, race, age, and education at enrollment - affect engagement and survey completion.

METHODS: From 2006-2013, ~250,000 adults were enrolled in the American Cancer Society’s Cancer Prevention Study-3 (CPS-3) and completed a baseline survey. In 2015 and every three years thereafter, participants received follow-up surveys to update exposure and health information. The response rate was calculated by dividing the number of completed surveys received by the total number of individuals who were alive at the start of the cycle and received a survey mailing during that period. In 2015 and every three years thereafter, participants received follow-up surveys to update exposure and health information. The response rate is calculated using the formula: Response = (usable returns) / (alive at the beginning of the cycle and mailed to during the cycle).We examined response patterns by race (white, Black, Hispanic, Asian, other), baseline age (<35, 35-44, 45-54, 55-64, and 65+ years), sex (male, female), and education (<high school, some college, 2-year/tech degree, 4-year degree, graduate degree).

RESULTS: Overall response decreased over time from 74% in 2015 to 66% in 2018 to 62% in 2021. Women consistently had higher response than men, an average 68% vs 63% respectively. Response rates among participants with higher educational attainment were more than 20% higher than participants with the lowest educational attainment on average. Response rates were steadily higher among older participants; participants aged 55 and older had more than 10% higher response rates than participants under age 45 at all-time points. White participants were more likely to respond over time, followed by Asian participants; and Black participants were least likely to respond.

DISCUSSION: In CPS-3, overall response to follow-up surveys is declining over time. Response rates were highest among participants who were female, White, more educated, and over 55 years. Strategies to increase sustained engagement, particularly in men, non-White, less educated, and younger individuals, should be explored to minimize attrition over time.