Clinical consequences of a miscalibrated digoxin immunoassay.

BACKGROUND: A routine audit revealed that the analytical method used to measure digoxin concentrations by our statewide pathology provider in 2009 was underestimating digoxin concentrations by 10%. The assay was recalibrated by the manufacturer in 2010, but clinical outcomes of the underestimation were never measured. This is a pilot study to describe the prescribing behavior around out-of-range digoxin concentrations and to assess whether miscalibrated digoxin immunoassays contribute to clinically relevant effects, as measured by inappropriate alterations in digoxin doses. METHODS: About 30,000 digoxin concentrations across the State Hospital system were obtained in 2 periods before and after recalibration of the digoxin assay. Digoxin concentration means were calculated and compared and were statistically significantly different. Subsequently, a single-centered retrospective review of 50 randomly chosen charts was undertaken to study the clinical implications of the underestimated concentrations. RESULTS: Mean digoxin concentrations for 2009 and 2011 were significantly different by 8.8% (confidence interval, 7.0%-10.6%). After recalculating the 2009 concentrations to their "corrected" values, there was a 16% increase in the number of concentrations within the range when compared with the 2011 concentrations (41.48% versus 48.04%). However, overall, this did not cause unnecessary dose changes in patients who were "borderline" or outside the therapeutic range when compared with controls (P = 0.10). The majority of decisions were based on the clinical impression rather than concentration alone (85.1% versus 14.9%), even when the concentration was outside the "therapeutic range." CONCLUSIONS: Although recalculating digoxin concentrations measured during 2009 to their corrected values produced a significant change in concentration and values inside and outside the range, this does not seem to have had an influence on patient treatment. Rather, clinicians tended to use the clinical impression to dose digoxin.

Giant hepatic haemangioma rupture in a patient on direct oral anticoagulant therapy.

Rupture of a liver haemangioma is extremely rare, with less than 100 cases reported in the literature. This is the first case known to date reporting a rupture occurring with direct oral anticoagulant therapy. A 76-year-old woman presented with acute abdominal pain and syncope in the context of commencing apixaban 4 weeks prior. Abdominal computed tomography and angiography demonstrated a large heterogenous mass in the left liver lobe with contrast blush suggestive of a bleeding tumour. Urgent transcatheter arterial embolization successfully ceased haemorrhage. Due to persistent compressive symptoms, a left lateral hepatectomy was performed. CD34 immunostaining of the tissue revealed variably sized vessels, which was consistent with a ruptured giant hepatic haemangioma. Our case substantiates the limited available literature regarding ruptured haemangiomas. Combined with previous case reports, this report will significantly contribute to our understanding of the risk factors, diagnosis and surgical indications for ruptured hepatic haemangiomas.