Association of CALLY index with NAFLD in U.S. adults from NHANES 2017-2020 assessed by vibration-controlled transient elastography.

Background: Non‑alcoholic fatty liver disease (NAFLD) is characterized by excessive hepatic fat accumulation and is closely associated with inflammation and metabolic dysregulation. The C‑reactive protein-albumin-lymphocyte (CALLY) index, a composite marker of inflammation, immunity, and nutritional status, remains understudied in relation to NAFLD.

Methods: A crosssectional analysis was conducted using data from 7,271 U.S. adults in NHANES 2017-2020. NAFLD was defined by vibrationcontrolled transient elastography with a controlled attenuation parameter (CAP) > 274 dB/m. Weighted logistic regression, restricted cubic spline (RCS) modeling, and twopiecewise logistic regression were applied to assess linear and nonlinear associations between the CALLY index and NAFLD prevalence. Subgroup and sensitivity analyses were performed to evaluate the consistency and robustness of the findings.

Results: The mean CALLY index was 8.08 (SD 12.42). Higher CALLY levels were inversely associated with NAFLD prevalence ( OR  = 0.96; 95% CI, 0.95-0.98). Compared with the lowest quartile (Q1 < 1.90), the highest quartile (Q4 > 10.00) showed a 61% lower prevalence of NAFLD (OR = 0.39; 95% CI, 0.24-0.64). RCS analysis demonstrated a significant nonlinear relationship, with a threshold at 8.91; below this value, each unit increase in the CALLY index corresponded to a 10% reduction in NAFLD prevalence (OR = 0.90; 95% CI, 0.88-0.92). Subgroup and sensitivity analyses yielded consistent results, confirming the robustness of these findings.

Conclusion: The CALLY index demonstrates a significant inverse association with NAFLD prevalence and may serve as a simple composite indicator for identifying individuals at higher likelihood of NAFLD, providing additional insights to inform future screening and risk‑stratification research.