Serum alkaline phosphatase, a risk factor for non-alcoholic fatty liver, but only for women in their 30s and 40s: evidence from a large cohort study.

BACKGROUND: Several risk factors are able to predict non-alcoholic fatty liver (NAFL) development, but the predictive value of serum alkaline phosphatase (ALP) remains uncertain. Our aim is to investigate the association between serum ALP levels and NAFL.

METHODS: 21,331 NAFL-free subjects were included. Sex-specific ALP quartiles (Q1 to Q4) were defined. With Q1 used as reference, hazard ratios (HRs) and 95% confidence intervals (CIs) were calculated across each quartile.

RESULTS: After adjusting for confounding variables, values in Q2, Q3 and Q4 had HRs (95%CIs) of 1.16 (0.94-1.43), 1.38 (1.13-1.69), 1.51 (1.24-1.83) in females and 0.99 (0.90-1.09), 1.04 (0.95-1.14), 0.96 (0.87-1.05) in males, respectively. A subgroup analysis of age factors in females, from Q2 to Q4, adjusted HRs (95%CIs) were 1.31 (0.81-1.99), 1.86 (1.23-2.81), 2.44 (1.60-3.71) in their 30 s, 1.13 (0.83-1.54), 1.17 (0.85-1.62), 1.65 (1.22-2.25) in their 40 s, and 0.95 (0.51-1.78), 0.91 (0.52-1.62), 0.89 (0.53-1.52) in their 50 s.

CONCLUSIONS: Higher serum ALP levels are considered a significant predictor for NAFL development in females aged 30 to 50.