Background: Autoimmune liver diseases (ALD) are a heterogeneous group of disorders affecting the hepatobiliary system and are characterized by specific autoantibodies. These are routinely measured in diagnostic laboratories using commercial line immunoblot (LIB) assays. However, the ordering characteristics and diagnostic performance of this test have not been extensively evaluated. This study aims to examine the performance of the ALD LIB in a single diagnostic laboratory.
Methods: A retrospective, cross-sectional audit of 12 months of data was performed at the Institute of Clinical Pathology and Medical Research diagnostic laboratory (Westmead Hospital, Australia). Patients referred for an ALD-LIB were included. Medical notes were reviewed to ascertain the clinical diagnoses of patients. Patients who had at least one positive ALD autoantibody on LIB were defined as “blot-positive” and compared with “blot-negative” patients. The performance of the ALD-LIB was assessed through the calculation of diagnostic sensitivities and specificities.
Results: There were 611 patients included over the 12-month period. Sixty-four of these patients (10%) were blot-positive. These patients were more likely to be female, to have other ALD-associated autoantibodies, and to have lower alkaline phosphatase (ALP) levels compared with blot-negative patients. An ALD diagnosis or systemic autoimmune disease was more likely to be identified in blot-positive patients. Finally, the LIB demonstrated a high negative predictive value for an ALD diagnosis in this patient cohort.
Conclusion: This real-world analysis of the laboratory’s ALD-LIB provided insights into the ordering characteristics and performance of this assay in patients referred for testing. When combined with other ALD investigations, the ALD-LIB is a useful adjunct in the evaluation of patients with suspected ALD.
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