Using liver enzymes as screening tests to predict mortality risk.

Area of Science:

• Biostatistics
• Epidemiology
• Clinical Chemistry

Background:

• Liver function tests (LFTs) are routinely assessed in clinical practice.
• The predictive value of specific LFTs for long-term mortality risk is an area of ongoing research.
• Understanding these associations can inform risk stratification and preventative strategies.

Purpose of the Study:

• To investigate the association between baseline liver function test results and all-cause mortality.
• To determine which LFTs are significant predictors of mortality in a large cohort of life insurance applicants.
• To compare the predictive power of different LFTs, including GGT, alkaline phosphatase, AST, and ALT.

Main Methods:

• A large-scale retrospective cohort study of 1,905,664 life insurance applicants.
• Mortality data obtained from the Social Security Master Death File, with 50,174 deaths observed.
• LFT values analyzed using percentiles and actual value ranges, stratified by age and sex groups.

Main Results:

• Gamma-glutamyl transferase (GGT) and alkaline phosphatase showed a linear, steep increase in relative mortality risk across their value distributions.
• Aspartate aminotransferase (AST) and alanine aminotransferase (ALT) demonstrated increased mortality risk at lower values.
• ALT did not predict mortality for values above the median distribution, while AST showed continued risk association.

Conclusions:

• GGT and alkaline phosphatase are significant, robust predictors of mortality risk across their entire range of values.
• AST is a more reliable indicator of mortality risk associated with transaminases compared to ALT.
• While ALT has utility in hepatitis screening, AST should be prioritized for mortality risk assessment in this population.