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

Abstract

Background: Alpha-1 antitrypsin (AAT) deficiency is often evaluated in patients with liver disease of unknown etiology.

Aims: We aimed to describe the practice and yield of AAT testing at a large clinical laboratory.

Methods: This is the retrospective cohort study of all patients with AAT measurements at one major clinical laboratory between 2003 and 2012.

Results: 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)].

Conclusion: 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.