AbstractBackground and AimsThe time lag encountered when accessing health‐care data is one major barrier to implementing opioid overdose prediction measures in practice. Little is known regarding how one's opioid overdose risk changes over time. We aimed to identify longitudinal patterns of individual predicted overdose risks among Medicaid beneficiaries after initiation of opioid prescriptions.Design, Setting and ParticipantsA retrospective cohort study in Pennsylvania, USA among Pennsylvania Medicaid beneficiaries aged 18–64 years who initiated opioid prescriptions between July 2017 and September 2018 (318 585 eligible beneficiaries (mean age = 39 ± 12 years, female = 65.7%, White = 62.2% and Black = 24.9%).MeasurementsWe first applied a previously developed and validated machine‐learning algorithm to obtain risk scores for opioid overdose emergency room or hospital visits in 3‐month intervals for each beneficiary who initiated opioid therapy, until disenrollment from Medicaid, death or the end of observation (December 2018). We performed group‐based trajectory modeling to identify trajectories of these predicted overdose risk scores over time.FindingsAmong eligible beneficiaries, 0.61% had one or more occurrences of opioid overdose in a median follow‐up of 15 months. We identified five unique opioid overdose risk trajectories: three trajectories (accounting for 92% of the cohort) had consistent overdose risk over time, including consistent low‐risk (63%), consistent medium‐risk (25%) and consistent high‐risk (4%) groups; another two trajectories (accounting for 8%) had overdose risks that substantially changed over time, including a group that transitioned from high‐ to medium‐risk (3%) and another group that increased from medium‐ to high‐risk over time (5%).ConclusionsMore than 90% of Medicaid beneficiaries in Pennsylvania USA with one or more opioid prescriptions had consistent, predicted opioid overdose risks over 15 months. Applying opioid prediction algorithms developed from historical data may not be a major barrier to implementation in practice for the large majority of individuals.