Classification and characteristics of on-label and off-label apixaban use in Denmark and Sweden

Purpose To estimate the proportion of apixaban users who received the drug for on-label indications and characterise the patients using apixaban for on-label and off-label indications. Methods We report results from two independently conducted studies in Denmark and Sweden, with 19,709 Danish and 17,592 Swedish patients, who received at least one outpatient dispensing of apixaban as identified through nationwide prescription registries. Indications, inferred from inpatient and hospital diagnoses recorded at the initial apixaban dispensing, were classified as on-label, off-label, or unclassified according to the Summary of Product Characteristics. All diagnoses were retrieved using inpatient or outpatient hospital diagnoses at the first outpatient dispensing during the study period. Results Men comprised 52% of the users in both Denmark and Sweden. The median age was 76 years (interquartile range [IQR]: 68-83 years) among Danish patients and 74 years (IQR: 67-82 years) among Swedish patients. An on-label indication could be assigned to 82.6% (95% confidence interval [CI]: 82.1%-83.1%) of the Danish patients and 86.4% (95% CI: 85.9%-86.9%) of the Swedish patients. The main on-label indication for apixaban was non-valvular atrial fibrillation (NVAF), which accounted for 76.1% of the indications in Denmark and 69.1% of the indications in Sweden. Off-label indications were assigned to 10.8% (95% CI: 10.3-11.2) of the Danish patients (main indication possible mechanical heart valve) and 7.7% (95% CI: 7.3-8.1) of the Swedish patients (main indication off-label atrial fibrillation). Conclusion The majority of apixaban initiators in Denmark and Sweden received apixaban for an on-label indication, primarily for NVAF.