Low yield and utilization of confirmatory testing in a cohort of patients with liver disease assessed for alpha-1 antitrypsin deficiency.

Abstract

Alpha-1 antitrypsin (AAT) deficiency is often evaluated in patients with liver disease of unknown etiology. We aimed to describe the practice and yield of AAT testing at a large clinical laboratory. This is the retrospective cohort study of all patients with AAT measurements at one major clinical laboratory between 2003 and 2012. AAT was measured in 4,985 patients by more than 339 physicians. Eight (0.16 %) patients were found to have AAT deficiency disease. Low AAT levels were associated with two clinical factors. Aspartate aminotransferase (>40 IU/L) was inversely related, odds ratio (OR) 0.53, 95 % CI (0.32-0.88), while comorbid pulmonary disease was positively correlated, OR 4.00, 95 % CI (1.37-9.30). Non-directed testing was common. More than 90 % of patients with ALT > 40 were simultaneously assessed for AAT deficiency, hepatitis B or C, hemochromatosis, and autoimmune hepatitis. Rates of phenotype utilization were low for patients with low AAT (23, 31.5 %). Phenotype utilization was inversely related to the practice of simultaneous testing for simultaneous autoimmune hepatitis [OR 0.34 (95 % CI 0.13-0.88)], hepatitis B [OR 0.32 (95 % CI 0.11-0.89)], hepatitis C [OR 0.36 (95 % CI 0.13-1.00)], and Wilson disease evaluation [OR 0.35 (95 % CI 0.14-0.92)]. The yield of AAT testing for patients with elevated liver enzymes is low. Utilization of phenotype testing is low and related to non-directed liver testing patterns. These data suggest a role for guidelines and laboratory protocols to encourage directed testing and phenotype utilization.