Clinical Impact of COVID-19 on Anticoagulation Management at the William S. Middleton Memorial Veterans Hospital

BACKGROUND

The COVID-19 pandemic has extensively impacted the delivery of routine medical care including anticoagulation management. The Veterans Affairs Clinical Pharmacy Practice Office (VA CPPO) has provided guidance to assist anticoagulation clinic providers in developing action plans to determine the risk vs benefit of delaying routine monitoring to reduce patient risk of COVID-19 exposure in the health care system.

Frequent laboratory monitoring of the International Normalized Ratio (INR) is needed to reduce the risk of bleeding and thromboembolic events for patients on warfarin. The Madison VA standard of care (SOC) includes routine INR monitoring at least every 6 weeks for stable patients taking warfarin. Alternatively, the benefit of routine laboratory monitoring for direct oral anticoagulants (DOACs) is less clear. Currently, the Madison VA recommends a complete blood count (CBC), serum creatinine (SCr), and liver function tests (LFTs) within 30 days prior to DOAC initiation, repeat CBC +/- SCr 1-3 months after DOAC initiation, then CBC/SCr every 6-12 months, monitored via the VA DOAC population management tool (PMT).

Per the 2012 American Society of Hematology (ASH) and the American College of Chest Physicians (CHEST) guidelines, for warfarin, 12-week follow-up may be considered in patients with chronically stable INRs (Kearon et. al. Chest 2012). Additionally, the Madison VA completed a prior prospective study of 12-week INR follow-up for patients taking warfarin which demonstrated safety of extended follow-up intervals. However, the number of participants able to achieve (56%) and maintain (34%) a 12-week INR follow-up were lower than anticipated (Porter et. al. J Thromb Thrombolysis 2016).

As of 3/30/2020, the Madison VA anticoagulation clinic followed 783 patients for warfarin management and 1742 patients for DOAC management.

STUDY DESIGN AND METHODS

A retrospective chart review to assess practice changes during the COVID-19 pandemic was conducted on anticoagulation patients with visits from 3/16/20 and 6/18/20 who were either on warfarin, transitioned to a DOAC, or newly initiated on DOAC therapy.

For patients on warfarin with 2 therapeutic INRs obtained at least 4 weeks apart, follow-up was extended to 8-12 weeks. Conversion to a DOAC was considered for eligible warfarin patients, excluding presence of mechanical heart valves, moderate to severe mitral valve stenosis, significant liver disease (Child Pugh C), or pregnancy/breastfeeding. As there are no accepted standards for DOAC laboratory monitoring, per the VA CPPO, stable baseline labs within the prior 6-12 months were acceptable. Routine laboratory monitoring after initiation could also be deferred and patients were transitioned to the DOAC PMT.

The data collected in the retrospective study was analyzed using descriptive statistics.

OBJECTIVES

The objective of this study was to assess patient safety and INR stability using the proposed COVID-19 extended follow-up parameters. If patient safety and stability could be maintained, it may lead to long term practice changes to extend follow-up and improve the anticoagulation clinic workload efficiency.

ENDPOINTS

The primary endpoint of the warfarin intervention was to determine the percentage of warfarin patients with therapeutic INRs after an extended interval. Secondary endpoints included the average length of the extended interval, bleeding or thromboembolic events during extended interval or within 30 days after the extended INR result. Other secondary endpoints included review of patient misadventures during the extended interval (e.g. patient taking incorrect warfarin doses), the percentage of patients with phone follow-up between extended INRs, and clinic time in therapeutic range (TTR).

The primary endpoint of the DOAC transition intervention was to determine the percentage of warfarin patients transitioned to DOACs during the specified timeframe. Secondary endpoints included the average time since last CBC/SCr for those transitioning from warfarin or newly initiating DOAC, percentage of patients without an INR at time of transition, and bleeding or thromboembolic events within 30 days of transition.