Normal serum aminotransferase concentration and risk of mortality from liver diseases: prospective cohort study

Abstract

Objective To examine the relation between the normal range of serum aminotransferase concentration and mortality from liver disease. Design Prospective cohort study. Setting Korea Medical Insurance Corporation study with eight years' follow up. Participants 94 533 men and 47 522 women aged 35-59 years. Main outcome measure Mortality from liver diseases according to death certificate. Results There was a positive association between the aminotransferase concentration, even within normal range (35-40 IU/l), and mortality from liver disease. Compared with the concentration < 20 IU/l, the adjusted relative risks for an aspartate aminotransferase concentration of 20-29 IU/l and 30-39 IU/l were 2.5 (95% confidence interval 2.0 to 3.0) and 8.0 (6.6 to 9.8) in men and 3.3 (1.7 to 6.4) and 18.2 (8.1 to 40.4) in women, respectively, The corresponding risks for alanine aminotransferase were 2.9 (2.4 to 3.5) and 9.5 (7.9 to 11.5) in men and 3.8 (1.9 to 7.7) and 6.6 (1.5 to 25.6) in women, respectively. According to receiver operating characteristic curves the best cut-off values for the prediction of liver disease in men were 31 IU/l for aspartate aminotransferase and 30 IU/l for alanine aminotransferase. Conclusion People with slightly increased aminotransferase activity, but still within the normal range, should be closely observed and further investigated for liver diseases.