The short-term effect of the COVID-19 pandemic on the management of warfarin therapy.

Aim    The aim of this study was to investigate the short-term effect of the COVID-19 pandemic on the management of warfarin therapy used for atrial fibrillation (AF) and prosthetic valve disease.Material and methods    The study included 139 Atrial fibrillation (AF) patients and 173 prosthetic valve patients (PVP) who were using warfarin. The time in therapeutic range (TTR), International Normalized Ratio (INR) averages, the numbers of INR tests, and the non-adherence to INR monitoring (NIM) were compared for the pre-covid period (PCP) and the COVID-19 period (CP). Also, adherence to warfarin therapy was evaluated with a questionnaire.Results    For all patients, the INR values were higher in the CP (2.47 vs 2.60, p<0.001), and the NIM percentage was higher (19.2 % vs 71.5 %, p<0.001) in the CP. The number of INR tests was lower during the CP (p<0.001).The percentage of patients with TTR≥70 % was lower during the CP (41.7 % vs 33 % p=0.017). Subgroup analysis showed that for PVP, TTR values and the percentage of patients with TTR ≥70 % were similar in both the PCP and CP periods. The questionnaire showed that for 94.1 % of respondents, the major cause of NIM in the CP was the COVID-19 pandemic. However, during the CP, adherence to warfarin medication was high (95.5 %).Conclusion    Lower TTR during the COVID-19 pandemic can increase bleeding and thromboembolic cases.Therefore, patients taking warfarin should be followed more closely, and more practical ways should be considered for INR testing.