Heparin-dependent platelet factor 4 antibodies and the impact of renal function on clinical outcomes: a retrospective study in hospitalized patients.

Patients who develop thrombocytopenia and heparin-dependent platelet factor 4 antibodies while on or shortly after receiving a heparin product are often considered for alternative anticoagulation to minimize the occurrence of life and limb-threatening events. We retrospectively reviewed the hospital records of 97 patients with heparin-dependent platelet factor 4 antibodies (at least 65 of whom were felt by the primary team to have HIT) to determine the influence of renal performance on alternative anticoagulant selection and associated clinical events. For GFR > 30, approximately 30% of patients who did not receive alternative anticoagulation had documentation of concern for HIT versus 60% of patients in the GFR < 30 group. We found that a smaller proportion of patients with severe renal insufficiency, GFRs < 30 ml/min/1.73 m(2) were treated with an alternative anticoagulant-this despite their high incidence of thromboembolic events and comparable rates of HIT. Overall, rates of hemorrhage did not differ between patients when compared to those without renal insufficiency. However, there was a higher percentage of hemorrhagic events for patients with GFR < 30 ml/min/1.73 m(2) on alternative anticoagulants. This study demonstrates that patient's with GFRs < 30 ml/min/1.73 m(2) need to be assessed for overall hemorrhagic risk at the time of starting an alternative anticoagulant and need to be monitored closely to avoid hemorrhagic events.