Serum aminotransferase activity and mortality risk in a United States community

Serum aminotransferase [such as aspartate aminotransferase (AST) and alanine aminotransferase (ALT)] is commonly used as an indicator of liver disease. The aim of the study was to determine the degree to which aminotransferase results are associated with increased mortality at the population level. All adult residents of Olmsted County, Minnesota, who had a health care encounter at Mayo Clinic, Rochester, in 1995 were identified and their AST or ALT results extracted from a laboratory database. These subjects were followed forward from January 1995 to April 2006 and their survival determined. To exclude patients with abnormal results because of a terminal illness, deaths within the first 2 years were excluded. The main outcome measure was survival. Standardized mortality ratios (SMRs) were calculated, based on Minnesota White death rates. During 1995, AST was measured at least once in 18,401 community residents, of whom 2,350 (13%) had results greater than the upper limit of normal (ULN). Of 6,823 subjects who had their ALT measured, 911 (13%) had results higher than ULN. Abnormal AST was associated with a significantly increased SMR (1.32 for 1-2 X ULN and 1.78 for > 2 X ULN). SMR was also higher for abnormal ALT (SMR = 1.21 for 1-2 X ULN and 1.51 for > 2 X ULN). In contrast, normal AST or ALT was associated with a risk of death lower than expected (SMR 0.95 for AST, 0.61 for ALT). Conclusion: Serum levels of AST and ALT obtained in a routine medical care setting are associated with future mortality in community residents.