Association Between the CALLY Index and Carotid Artery Stenosis Severity in Patients Younger and Older than 65 Years

Background/Objectives: Atherosclerosis is a multifaceted inflammatory condition closely linked to immunonutritional status. The C-reactive protein-albumin-lymphocyte (CALLY) index is a composite marker of immunonutrition. We assessed the relationship between this index, age, and carotid stenosis in individuals undergoing carotid Doppler ultrasonography. Methods: Individuals who underwent routine carotid Doppler ultrasonography were retrospectively analyzed. Carotid stenosis was categorized by severity, and bilateral intima-media thickness was recorded. The composite index integrating C-reactive protein, albumin, and lymphocyte parameters was derived from laboratory parameters. Traditional cardiovascular risk factors, including hypertension, diabetes mellitus, hyperlipidemia, and smoking status, were also recorded and incorporated into multivariable analyses. Sex-related differences were additionally evaluated using sex-stratified correlation analyses. Results: Among 1516 patients, 895 (59.1%) were younger than 65 years and 621 (40.9%) were aged 65 years and above. Carotid artery stenosis and intima-media thickness were significantly higher in individuals aged 65 years and above. The mean index value was significantly lower in the older group (4.0 versus 8.3; p < 0.001). Hypertension, diabetes mellitus, and hyperlipidemia were significantly more prevalent in patients with carotid stenosis (p < 0.001 for all), whereas smoking was not associated (p > 0.05). Male sex was independently associated with carotid stenosis, and sex-stratified analyses demonstrated similar inverse associations between age and CALLY index values in both sexes. In multivariable analysis, lower index values were independently associated with carotid stenosis and carotid intima-media thickness in both age groups. In the overall cohort, the index demonstrated moderate discriminatory performance (area under the curve = 0.724). Similar moderate performance was observed in the <65 (AUC = 0.681) and ≥65 (AUC = 0.685) subgroups. Conclusions: The CALLY index was independently associated with carotid stenosis and CIMT after adjustment for traditional cardiovascular risk factors. Although effect sizes were comparable between age groups, CALLY index levels were lower in older individuals. These findings suggest that the CALLY index may provide complementary information in the assessment of carotid atherosclerosis, particularly in elderly populations. However, given the retrospective cross-sectional design and moderate discriminatory performance, it should not be interpreted as a standalone, causal, or disease-specific marker.