Anti Factor Xa monitoring for venous thromboprophylaxis in severely burn-injured patients: a systematic review

Patients with severe burn injuries are at risk of venous thromboembolism (VTE) and associated sequelae. Burn-injured patients may require larger doses of VTE prophylaxis so underdosing may occur with standard regimens. Monitoring anti-factor Xa (AFXa) levels may allow tailoring of dosage but is currently uncommon. The purpose of this systematic review was to methodically review the available literature with respect to AFXa in severe burn-injured patients, and thereby assess its efficacy. Using PRISMA guidelines, "Xa" and "burns" were used to systematically review MEDLINE (1946 - present) and EMBASE (1974 - present) databases for publications regarding the monitoring of AFXa levels for thromboprophylaxis in burninjured patients. Eight studies (432 patients) met inclusion. Peak AFXa level at initial measurement was reported in all studies and was within the range for prophylaxis in 184 of 432 cases (42.6%), below range in 246 of 432 cases (56.9%) and above range for 2/432 (0.5%). Complications were reported in 7 studies (412 patients), with a total of 30 (7.3%) complications, comprising of 16 (53.3%) VTE events and 14 (46.7%) mortalities. Three studies comprising 270 patients compared complications between patients who were within the reference range with patients who were below the range. There were 164 patients from the 'within the reference range' groups that had a total of 6 (3.7%) complications, comprised of 4 (66.7%) VTE events and 2 (33.3%) mortalities. There were 106 patients from the 'below reference range group' that had a total of 11 (10.4%) complications, comprised of 9 (81.8%) VTE events and 2 (18.2%) mortalities. Our findings suggest standard prophylactic anticoagulation dosing risks underdosing and therefore, an increased risk in the development of VTE. AFXa monitoring allows individually tailored dose adjustment to reach therapeutic levels, which may be efficacious in reducing VTE events and is therefore recommended where possible.