Researchers Find Increased Bleeding Among Patients Taking Warfarin Who Abuse Alcohol, Drugs

Researchers at the Bedford VA and Boston University School of Medicine (BUSM) have found that substance abusers who take warfarin had more bleeding events than non-abusers. Additionally, they found that commonly obtained blood lab values might predict which patients with alcohol abuse are at a greater risk for bleeds. These findings were recently reported in the Journal of General Internal Medicine.

Drug and alcohol abuse is extremely common and some patients with substance abuse may have conditions requiring anticoagulation with blood thinning agents such as warfarin. However, the safety of prescribing warfarin among these patients is unknown. The researchers examined various labs and characteristics that might predict poor anticoagulation control and hemorrhagic events.

Among their findings:

  • Patients with drug or alcohol abuse taking warfarin had poorer anticoagulation control and more major bleeds;
  • Two common laboratory values of liver function, AST and ALT, specifically a ratio of theses values >1.5, predicted which patients with alcohol abuse were most likely to have poor outcomes.

Lydia Efird
Lydia Efird

“The results of this study may help doctors individualize the risks of treatment with each patient and direct future interventions,” said lead author Lydia Efird,MD, resident physician in Internal Medicine at BUSM. “Prescribing anticoagulation therapy to patients who abuse alcohol and drugs is challenging. Hopefully these findings will help clinicians stratify which of these patients may safely receive warfarin and in which patients it is best avoided,” she added.

This study was supported by the Center for Health Quality, Outcomes, and Economic Research, Bedford VA Medical Center and a grant from VA Health Services Research and Development (IIR-10-374).