The primary purpose of this study is to evaluate the effectiveness of an intervention with a mobile adherence platform, compared to physician- or nurse-guided standard of care, to improve medication adherence to rivaroxaban in participants who have recently initiated treatment with rivaroxaban for stroke prevention in atrial fibrillation based on an assessment of the proportion of days covered (PDC) of rivaroxaban treatment.

Inclusion Criteria:

• A history of atrial fibrillation
• Taking newly-prescribed rivaroxaban for atrial fibrillation for less than or equal to (<=) 90 days or who are about to initiate therapy (with a prescription dated in the last 90 days)
• At least 1 of the 4 questions answered "yes" from the four-item Morisky Medication Adherence Scale (MMAS-4)
• Possession of a compatible smartphone with an active phone number, text and data plan. The smartphone must be in continued possession of the participant. It may not be a shared device and must exclusively remain in the possession of the participant during the study period. The smartphone must have an active cellular phone number and cellular data subscription. WiFi internet capability is not a substitute for an active cellular data plan
• Willing to have the adherence application installed on a smartphone and use it every day during the entire study period
• Must sign an informed consent form (ICF) indicating that he or she understands the purpose of, and procedures required for, the study and is willing to participate in the study and is willing to authorize the study team to contact the participant's pharmacy for oral anticoagulation medication and refill data
• Willing to provide oral confirmation indicating that he/she has not previously used a medication adherence application
• Ability to read and understand English

Exclusion Criteria:

• Anticipated inability to adhere to the mobile application (Care4Today) based on opinion of site Principal Investigator (PI)
• Anticipated rivaroxaban use less than (<) 12 months based on clinical documentation or participant interview
• Prescribed rivaroxaban for indications other than atrial fibrillation (Prescriptions for concomitant conditions are allowed as long as 1 of the indications is atrial fibrillation)
• Current use of: specialized anticoagulation clinics for rivaroxaban medication management; specialized pharmacist-led adherence or refill monitoring; or enrollment in a medication adherence program even if that program is for medications other than rivaroxaban
• Current use of adherence tracking devices, hardware, smartphone or computer applications, including but not limited to smart pill bottles, pill timers, radiofrequency tagged medications or dispensers, mobile applications, or automated phone reminders. Pharmacy and health care plan automated refill reminders are permitted and are not exclusion. Pill organizers or containers that only compartmentalize a participant's medications based on days of the week are not exclusion. Pill organizers that remind participants when to take medicine with beeps or alerts are exclusion
• Cognitive, visual, hearing, voice, or motor impairment that would prevent completion of study procedures or use of mobile phone
• Employee of the investigator or study site, with direct involvement in the proposed study or other studies under the direction of that investigator or study site, as well as family members of the employees or the investigator