STUDY OBJECTIVE: To evaluate whether using an immunoglobulin G (IgG)-specific platelet factor 4 (PF4) test reduces the rate of positive PF4 results and has an impact on prescribing practices of nonheparin anticoagulants (direct thrombin inhibitors and fondaparinux) in patients assessed for heparin-induced thrombocytopenia (HIT). DESIGN: Single-center prospective cohort study with a historical control group. SETTING: Large academic medical center. PATIENTS: A total of 672 patients assessed for HIT. INTERVENTION: Patients were assessed for HIT by using either an IgG-specific PF4 enzyme-linked immunosorbent assay (ELISA; 336 patients) or a nonspecific PF4 ELISA (336 patients; historical control group). MEASUREMENTS AND MAIN RESULTS: No significant difference was noted in the proportion of patients with a low, intermediate, or high risk of HIT based on the 4Ts pretest clinical scoring system. The PF4 ELISA was positive in 6.9% versus 11.3% of patients (p=0.04) in the IgG-specific and nonspecific cohorts, respectively. A smaller proportion of patients were prescribed a direct thrombin inhibitor in the IgG-specific cohort (19.4% vs 25.9%; p=0.04). No significant difference in fondaparinux use was noted between the cohorts. The duration of direct thrombin inhibitor therapy, bleeding events, hospital length of stay, and in-hospital mortality was similar in both cohorts. CONCLUSION: Use of an IgG-specific PF4 ELISA was associated with a lower rate of positive PF4 test results. Direct thrombin inhibitor prescribing was also significantly lower during the time period where the IgG-specific PF4 ELISA was used, with no significant differences noted in safety outcomes.
STUDY OBJECTIVE: To evaluate whether using an immunoglobulin G (IgG)-specific platelet factor 4 (PF4) test reduces the rate of positive PF4 results and has an impact on prescribing practices of nonheparin anticoagulants (direct thrombin inhibitors and fondaparinux) in patients assessed for heparin-induced thrombocytopenia (HIT). DESIGN: Single-center prospective cohort study with a historical control group. SETTING: Large academic medical center. PATIENTS: A total of 672 patients assessed for HIT. INTERVENTION: Patients were assessed for HIT by using either an IgG-specific PF4 enzyme-linked immunosorbent assay (ELISA; 336 patients) or a nonspecific PF4 ELISA (336 patients; historical control group). MEASUREMENTS AND MAIN RESULTS: No significant difference was noted in the proportion of patients with a low, intermediate, or high risk of HIT based on the 4Ts pretest clinical scoring system. The PF4 ELISA was positive in 6.9% versus 11.3% of patients (p=0.04) in the IgG-specific and nonspecific cohorts, respectively. A smaller proportion of patients were prescribed a direct thrombin inhibitor in the IgG-specific cohort (19.4% vs 25.9%; p=0.04). No significant difference in fondaparinux use was noted between the cohorts. The duration of direct thrombin inhibitor therapy, bleeding events, hospital length of stay, and in-hospital mortality was similar in both cohorts. CONCLUSION: Use of an IgG-specific PF4 ELISA was associated with a lower rate of positive PF4 test results. Direct thrombin inhibitor prescribing was also significantly lower during the time period where the IgG-specific PF4 ELISA was used, with no significant differences noted in safety outcomes.
Authors: Brianne M Ritchie; Katelyn W Sylvester; David P Reardon; William W Churchill; Nancy Berliner; Jean M Connors Journal: J Thromb Thrombolysis Date: 2016-11 Impact factor: 2.300