PT - JOURNAL ARTICLE AU - Rees-Punia, Erika AU - Nelson, Jillian AU - Briggs, Peter J AU - Joiner, Nance AU - Hodge, James M AU - Bontemps-Jones, Jeuneviette E AU - Bloodworth, Den E AU - Yeager, Ashley AU - McCrary, Jeshondria AU - Patel, Alpa TI - Nation-wide cohort of device-measured sedentary time and physical activity in the USA—the Cancer Prevention Study-3 (CPS-3) Accelerometry Substudy: cohort profile AID - 10.1136/bmjopen-2024-085896 DP - 2025 Jan 01 TA - BMJ Open PG - e085896 VI - 15 IP - 1 4099 - http://bmjopen.bmj.com/content/15/1/e085896.short 4100 - http://bmjopen.bmj.com/content/15/1/e085896.full SO - BMJ Open2025 Jan 01; 15 AB - Purpose This paper describes the data collection and management methods for the Cancer Prevention Study-3 (CPS-3) Accelerometry Substudy, a nested cohort of device-based physical activity and sedentary time data.Participants US-based CPS-3 participants (initially enrolled 2006–2013) who completed the 2018 follow-up survey and had a valid email address were invited to the Accelerometry Substudy (n=109 780). Among the 23 111 participants who registered and were shipped an ActiGraph GT3X+ accelerometer, 21 219 participants returned the device with a complete wear log (91.8%) and 20 950 (90.6%) provided at least three adherent days of data (eg, days with at least 10 hours of wear).Findings to date Participants with ≥3 adherent days were predominantly female (n=16 187, 77.3%), non-Latino white (n=17 977, 85.8%) and had an average age of 58 years (SD=9.8). The median daily wear time was 15.3 hours, which did not vary considerably by wear day. The median time spent in moderate-intensity aerobic physical activity was 29 min/day (IQR=36), and the median time in vigorous physical activity was 3 min/day (IQR=13). Participants were sedentary for 9.4 hours (564 min, IQR=171 min) and accumulated a median of 6474 steps per day (IQR=5348).Future plans The full CPS-3 cohort will be linked with the National Death Index and state cancer registries biennially. Participants will be sent triennial surveys for the next two decades. Future analyses within the CPS-3 Accelerometry Substudy more specifically aim to identify relationships between physical activity, sedentary time and health outcomes, primarily cancer incidence, survival and survivorship.Data are available upon reasonable request. Data are available from the American Cancer Society by following the ACS Data Access Procedures (https://www.cancer.org/research/population-science/research-collaboration.html) for researchers who meet the criteria for access to confidential data. Please email cohort.data@cancer.org to inquire about access.