Platelet aggregation inhibitors, platelet function testing, and blood loss in hip fracture surgery.

Background: The purpose of our prospective study was to analyze how many patients with hip fractures are on treatment with platelet aggregation inhibitors (aspirin and clopidogrel), how many of these patients have impaired platelet function as measured by the PFA-100, and whether there is an association between perioperative blood loss and either intake of platelet inhibitors or platelet function.

Methods: Four hundred sixty-two patients with hip fractures were investigated. Surgery (most commonly dynamic screw fixation and hemiarthroplasty) was performed on day 1.3 (in patients on clopidogrel on day 3). Platelet function analysis was performed with the PFA-100, using the collagen and epinephrine closure time. Transfusion requirement and drain blood loss were measured.

Results: Ninety-eight patients (21%) were on treatment with aspirin, of those, 64 patients (65%) had impaired platelet function. Twenty-two patients (5%) were on clopidogrel, of those, 15 patients (68%) had impaired platelet function. Of the patients without platelet aggregation inhibitors, 29% had impaired platelet function. Mortality, major bleeding, red blood cell requirement, and drainage blood loss did not correlate with platelet aggregation inhibitor intake or platelet function.

Conclusions: It is not possible to predict the platelet function by asking patients about intake of aspirin or clopidogrel. Perioperative blood loss did not correlate with either history of platelet aggregation inhibitor intake or platelet function as determined by PFA-100. Therefore, the measurement of platelet function is of little clinical relevance in patients with hip fractures. In patients treated with aspirin, surgery should not be delayed, and patients on clopidogrel can be operated on 3 days after stopping the drug without increased bleeding risk.