The Impact of the CALLY Index on All‐Cause Mortality in Patients With Depression: A Longitudinal Analysis Using NHANES Data

ABSTRACT Background and Aim The C‐reactive protein‐albumin‐lymphocyte (CALLY) index is an emerging biomarker, yet, its potential association with all‐cause mortality risk in patients with depression remains unexplored. The present investigation sought to evaluate this potential correlation. Methods This analysis included 4,426 adults with depression from the National Health and Nutrition Examination Survey (NHANES) (2005–2010, 2015–2016). The CALLY index was calculated as (lymphocyte count × albumin)/CRP × 10³. Multivariable Cox regression was used to assess its association with all‐cause mortality. Restricted cubic spline (RCS) and Kaplan‐Meier curves examined nonlinear relationships and survival probabilities across strata. Results Over a median follow‐up of 121 months, the cumulative all‐cause mortality rate was 14.84%. Cox regression showed that each one‐unit increase in log‐transformed CALLY index was associated with a 41% lower risk of all‐cause mortality. When categorized into quartiles, the highest quartile (Q4) demonstrated significantly lower hazard ratios (HR) across all models compared to the lowest (Q1). Kaplan‐Meier analysis revealed an inverse relationship between CALLY index levels and mortality ( p < 0.0001). RCS analysis identified a nonlinear l ‐shaped association ( p ‐trend < 0.001), with an inflection point at Log‐CALLY = 4.09. Subgroup analyses indicated that smoking status, poverty income ratio(PIR), chronic respiratory diseases(CRD), and diabetes significantly modified this association (all p for interaction < 0.05). Conclusion The CALLY index was independently associated with all‐cause mortality in patients with depression, with lower values indicating higher long‐term mortality risk. It may serve as a potential prognostic marker reflecting inflammation and nutritional status in this population.