(B-130) Initiation of anticoagulants during the COVID-19 pandemic in Sweden: an interrupted time series analysis

Background: The COVID-19 pandemic may have increased anticoagulant initiation rates due to the thrombogenic nature of the disease, or decreased initiation rates due to the societal impact of the pandemic.

Objectives: We aimed to study the effect of the COVID-19 pandemic on initiation of oral anticoagulants or heparins in Sweden.

Methods: We used national registry data from the “Swedish COVID-19 Investigation for Future Insights – a Population Epidemiology Approach using Register Linkage” (SCIFI-PEARL) project database. We conducted a new user design, single interrupted time series analysis on the monthly cumulative incidence of initiation (new dispensing) of any anticoagulant, direct oral anticoagulants (DOACs), warfarin, or heparins, before and after March 2020, assessed from the National Prescription Drug Register. The study population included all people ≥18 years resident in Sweden on 1 Mar 2019 who were dispensed an anticoagulant 1 Mar 2019 - 31 Jul 2022, with no dispensings 14 months prior. Patients who died, emigrated or started a new anticoagulant drug were excluded from the denominator at the end of each period. We fitted linear segmented regression models with a lag of 12 months to account for autocorrelation.

Results: There were 492,177 new users of anticoagulants, 55% female, mean age 63.3 years. Most patients received heparins (51%), followed by DOACs (47%) and warfarin (1.4%). For anticoagulants in total, there were no substantial or statistically significant changes or differences in the trends of initiation after the start of the COVID-19 pandemic. There were slight but non-significant numerical decreases in initiation at onset of the pandemic in March 2020, particularly for DOACs. For individuals aged ≥ 65 years, this decrease was considerable for DOACs (-45/100,000, 95%CI -86 to -3.4, p=0.04). The pre-pandemic declining trend of warfarin initiation seemed to attenuate, i.e., became less negative, after March 2020 (post-trend change +0.092/100,000 per month, 95%CI 0.056 to 0.13, p< 0.0001).

Conclusions: We did not find any profound effect of the COVID-19 pandemic on the initiation of anticoagulants in total. However, among those aged ≥ 65 years, a notable immediate decrease in initiation of DOACs was observed. Furthermore, the onset of the pandemic may have attenuated the downward temporal trend in initiation of warfarin.