Adverse drug event carries a significant burden of inpatient hospital care, incurs more cost, and leads to increased loss of life. Targeted policies to reduce them could potentially help decrease mortality as well as drive down cost. Copyright © 2017 John Wiley & Sons, Ltd.

Recently published reports have established a heparin-induced thrombocytopenia (HIT)-mimicking thromboembolic disorder without proximate heparin exposure, called spontaneous HIT syndrome. Although the pathophysiology remains unclear, anti-platelet factor 4 (PF4)/heparin antibodies possibly triggered by exposure to knee cartilage glycosaminoglycans or other non-heparin polyanions found on bacterial surfaces and nucleic acids have been postulated. We present a 53-year-old female receiving antithrombotic prophylaxis with aspirin following right total knee replacement surgery (without perioperative or any previous lifetime heparin exposure) who acutely presented with high-risk pulmonary embolism (PE) and right great saphenous vein thrombophlebitis on postoperative day (POD) 14; her platelet count at presentation was 13 × 10/L. Prior to diagnostic consideration of spontaneous HIT syndrome, the patient briefly received unfractionated heparin (UFH) and one dose of enoxaparin. The patient's serum tested strongly positive for anti-PF4/heparin antibodies by two different PF4-dependent enzyme-linked immunosorbent assays (ELISAs) and by serotonin release assay (SRA). Failure of fondaparinux anticoagulation (persisting HIT-associated disseminated intravascular coagulation) prompted switching to argatroban. Severe thrombocytopenia persisted (platelet count nadir, 12 × 10/L, on POD21), and 9 days after starting argatroban symptomatic right leg deep-vein thrombosis (DVT) occurred, prompting switch to rivaroxaban. Thereafter, her course was uneventful, although platelet count recovery was prolonged, reaching 99 × 10/L by POD45 and 199 × 10/L by POD79. The patient's serum elicited strong serotonin release in the absence of heparin (seen even with 1/32 serum dilution) that was enhanced by pharmacological concentrations of UFH (0.1 and 0.3 IU/mL) and fondaparinux (0.1-1.2 μg/mL, i.e., in vitro fondaparinux "cross-reactivity"). Ultimately, platelet count recovery was associated with seroreversion to a negative SRA (documented at POD151). Our literature review identified joint replacement surgery, specifically knee replacement, to be a relatively common trigger of spontaneous HIT syndrome. Further, including our patient case, 5 of 7 patients with spontaneous HIT syndrome post-orthopedic surgery who received treatment with argatroban developed new and/or progressive lower-limb DVT or recurrent PE despite anticoagulation with this parenteral direct thrombin inhibitor, suggesting that this patient population is at high risk of breakthrough thrombotic events despite treatment with this HIT treatment-approved anticoagulant. Our case also illustrates successful outcome with rivaroxaban for treatment of spontaneous HIT syndrome, consistent with emerging literature supporting safety and efficacy of direct oral anticoagulant therapy for treatment of acute HIT.

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Hypercalcemia from cosmetic injections can be severe and life threatening and can present years after the initial procedure. Cosmetic injection-associated granuloma should be considered a cause of hypercalcemia, especially in middle-aged females presenting with non-PTH-mediated, non-malignant hypercalcemia, which is often associated with elevated calcitriol; however, it should be noted that calcitriol level may be normal as well.

Both apixaban and rivaroxaban have been approved for use in acute venous thromboembolism (VTE). Although indirect comparison through network meta-analyses of randomized trials have been performed to compare the efficacy and safety of these agents, further comparison between these agents was lacking until recently. We sought to systematically review and carry out a meta-analysis of studies to further compare apixaban with rivaroxaban from multiple studies done in the real-world settings. Studies comparing rivaroxaban with apixaban in patients with acute VTE were identified through electronic literature searches of MEDLINE, EMBASE, Scopus, and the Cochrane library up to May 2019. Study-specific risk ratios (RRs) were calculated and combined using a random-effects model meta-analysis. In an analysis involving 24 041 patients, recurrent VTE within 6 months occurred in 56 of 4897 patients (1.14%) in the apixaban group and 258 of 19 144 patients (1.35%) in the rivaroxaban group (RR, 0.89; 95% confidence interval [CI], 0.67-1.19; P = .45). Clinically relevant major bleeding occurred in 85 of 11 559 patients (0.74%) in the apixaban group and 350 of 33 909 patients (1.03%) in the rivaroxaban group (RR, 0.73; 95% CI, 0.58-0.93; P = .01). Clinically relevant nonmajor bleeding occurred in 169 of 3417 patients (4.95%) in the apixaban group and 1094 of 12 475 patients (8.77%) in the rivaroxaban group (RR, 0.59; 95% CI, 0.50-0.70; P < .01). Apixaban shows equivalent efficacy in prevention of recurrent VTE but decreased risk of major and minor bleeding events compared with rivaroxaban.