The primary objective is to assess the proportion of Non-valvular atrial fibrillation (NVAF) patients receiving the standard dose of 20 mg of rivaroxaban or the reduced dose of 15 mg of rivaroxaban.

The secondary objective is to determine if dosing patterns for rivaroxaban may be influenced by baseline chronic kidney disease (CKD) status (as a proxy for measured baseline renal function).

Inclusion Criteria:

• NVAF (non-valvular atrial fibrillation) will be defined as the occurrence of 2 or more inpatient or outpatient claims with International Classification of Disease ICD-9 427.31 as the diagnosis code at any time in the patient's data history prior to inclusion
• Patients will be required to have 180 days of enrollment for the assessment of baseline characteristics
• CHA2DS2-Vasc score ≥2 during the 180 days prior to index rivaroxaban use baseline period
• Evidence of continuous enrollment in MarketScan during 180 days before the date of the first prescription of rivaroxaban

Exclusion Criteria:

• Patients <18 years of age
• Patients with valvular AF (atrial fibrillation)
• Pregnancy
• Malignant cancers
• Transient cause of AF
• Patients with VTE (Venous thromboembolism), pulmonary embolism or DVT (Deep Vein Thrombosis)
• Patients with major surgery defined as hip or knee replacement
• Prescriptions of OACs (Oral anticoagulants) (apixaban,warfarin, dabigatran, rivaroxaban) before index date
• Prescription of more than one OAC on the index date

Patients with non-valvular atrial fibrillation (NVAF)