A prospective, blinded study of a PF4-dependent assay for HIT diagnosis.

Heparin-induced thrombocytopenia (HIT) is a life-threatening, prothrombotic, antibody-mediated disorder. To maximize the likelihood of recovery, early and accurate diagnosis is critical. Widely available HIT assays, such as the platelet factor 4 (PF4) heparin enzyme-linked immunosorbent assay (ELISA) lack specificity, and the gold-standard carbon 14-labeled serotonin release assay (SRA) is of limited value for early patient management because it is available only through reference laboratories. Recent studies have demonstrated that pathogenic HIT antibodies selectively activate PF4-treated platelets and that a technically simpler assay, the PF4-dependent P-selectin expression assay (PEA), may provide an option for rapid and conclusive results. Based upon predefined criteria that combined 4Ts scores and HIT ELISA results, 409 consecutive adults suspected of having HIT were classified as disease positive, negative, or indeterminate. Patients deemed HIT indeterminate were considered disease negative in the primary analysis and disease positive in a sensitivity analysis. The ability of PEA and SRA to identify patients judged to have HIT was compared using receiver operating characteristic curve statistics. Using these predefined criteria, the diagnostic accuracy of PEA was high (area under the curve [AUC], 0.94; 95% confidence interval [CI], 0.87-1.0) and similar to that of SRA (AUC, 0.91; 95% CI, 0.82-1.0). In sensitivity analysis, the AUCs of PEA and SRA were also similar at 0.88 (95% CI, 0.78-0.98) and 0.86 (95% CI, 0.77-0.96), respectively. The PEA, a technically simple nonradioactive assay that uses ∼20-fold fewer platelets compared with the SRA, had high accuracy for diagnosing HIT. Widespread use of the PEA may facilitate timely and more effective management of patients with suspected HIT.

Comparative effectiveness of rasburicase versus allopurinol for cancer patients with renal dysfunction and hyperuricemia.

While rasburicase has shown efficacy to rapidly correct hyperuricemia compared with allopurinol, its overall impact in improving clinically significant outcomes, such as acute kidney injury (AKI), in tumor lysis syndrome (TLS) is unknown. In this retrospective cohort study, we included all hospitalized cancer patients with hyperuricemia and AKI who received rasburicase +/- allopurinol or allopurinol alone from 2009 to 2015. Inverse probability of treatment weighting using propensity score was used to account for potential confounders and to estimate the causal effect associated with differential drug treatment. 150 patients met inclusion criteria; 89 received rasburicase +/- allopurinol and 61 received allopurinol alone. Weighted outcome regression analysis demonstrated that rasburicase was associated with significantly lower mean uric acid nadir at 7 days compared to allopurinol (2.70 versus 5.82 mg/dL, p < 0.01). However, likelihood of renal function recovery (OR = 0.90, p = 0.79), creatinine nadir by 7 days (1.80 versus 1.66 mg/dL, p = 0.51), and final creatinine by 30 days (2.08 versus 2.07 mg/dL, p = 0.98) did not significantly differ. In conclusion, the clinical benefit of rasburicase in promoting renal function recovery in cancer patietns with concurrent hyperuricemia and renal failure remains inconclusive. Our results suggest that correction of hyperuricemia as a surrogate endpoint may not be associated with significant renal function improvement, particularly if renal dysfunction is unrelated to TLS.

Utilization patterns and clinical outcomes of rasburicase administration according to tumor risk stratification.

PURPOSE: Current guidelines for tumor lysis syndrome management recommend rasburicase for high-risk patients. Adherence to guidelines has not been well studied, and the correlation between uric acid reduction and clinically relevant outcomes, such as acute kidney injury, remains unclear. Our study aims to describe rasburicase utilization patterns and outcomes in cancer patients with varying risks for tumor lysis syndrome. METHODS: In this retrospective cohort study, we included cancer inpatients who received rasburicase for tumor lysis syndrome management at two affiliated academic hospitals from 2009 to 2015. Patients were classified by tumor lysis syndrome risk categories prior to drug administration. Primary outcomes included acute kidney injury incidence and renal recovery. Secondary outcomes included uric acid nadir, mortality, and hospital length-of-stay. RESULTS: Among 164 patients, 42 (26%) had high-, 63 (38%) had intermediate-, and 59 (36%) had low-risk for tumor lysis syndrome. A total of 94 patients (57%) had existing renal dysfunction prior to rasburicase use. This occurred more frequently in low- (68%) compared to intermediate- (57%) and high- (43%) risk patients (p = 0.044). A greater proportion of patients in the high-risk group (78%) had renal recovery when compared to the intermediate- (61%) or low- (45%) risk groups (p = 0.056). Despite a similar length of stay, the high-risk group had a significantly lower 30-day mortality (10%) when compared to intermediate- (25%) or low- (32%) risk groups (p = 0.029). CONCLUSIONS: Our results suggest that rasburicase may be frequently prescribed to treat hyperuricemia unrelated to tumor lysis syndrome in cancer patients. Improved education and adherence to guidelines may improve clinical and economic outcomes associated with rasburicase administration.