Adverse Prognosis of AntiPF4Heparin Antibodies

An emerging issue is whether anti-PF4/heparin antibodies confer adverse prognosis even in the absence of clinically-overt HIT. Mattioli and coworkers (2000) found a higher 1 yr event-rate (death, MI, recurrent angina, revascularization, or stroke) among patients who formed anti-PF4/heparin antibodies following UFH treatment for unstable angina (66% vs. 44%; p < 0.01). Williams and colleagues (2003), using blood samples obtained 48 h after entry into a clinical trial of non-ST-segment elevation MI, found that death or MI was increased at 1 mo (OR, 4.0; p = 0.0093) among patients with a positive anti-PF4/polyanion EIA. Bennett-Guerrero et al. (2005) observed a higher risk of in-hospital death or hospitalization beyond 10 days (OR, 1.98; p = 0.0284) among postcardiac surgery patients with a positive EIA for anti-PF4/heparin antibodies prior to cardiac surgery. Finally, Peña de la Vega and coworkers (2005) found in a cross-sectional study of chronic HD patients that the presence of anti-PF4/polyanion antibodies corresponded to a higher mortality at mean 620-day follow-up (hazard ratio, 2.47; p = 0.03). In none of these studies did clinically evident HIT appear to explain these differences. Despite the implication of these studies that these antibodies might be pathogenic, an alternative view is that unrecognized confounders explain their apparent adverse prognosis. For example,

Immunogenicity

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