Role of abdominal aortic calcification score in predicting cardiovascular risk in the general population.

Background: Abdominal aortic calcification (AAC) is closely related to cardiovascular disease. Although its clinical significances have primarily been investigated in patients with chronic kidney disease, its association with cardio-cerebrovascular mortality in the general middle-aged and elderly population has not been sufficiently investigated.

Aims: To study the association of AAC and cardio-cerebrovascular mortality in both the entire general middle-aged and elderly populations and age subgroups.

Methods: Data of participants of the National Health and Nutrition Examination Survey (NHANES) 2013-2014 were analyzed. This study included middle-aged and elderly (≥ 40 years old) individuals who underwent dual-energy X-ray absorptiometry. The severity of AAC was assessed by an AAC scoring system (AAC score) with a maximum possible value of 24. Participants were tracked for survival status and major cause of death till 31st December 2019. This study utilized AAC score = 6 as the optimal cut-off according to Harrell's c statistic. Based on AAC scores, participants were trichotomized (0, 0-6, and ≥ 6). Groupwise survival curves and cumulative incidence functions were plotted to reveal the association of AAC and cardio-cerebrovascular mortality. Given results under trichotomization, combination of participants with AAC scores 0 and 0-6 was conducted to reaffirm the association of AAC and adverse prognosis.

Results: Correlation between increased AAC score and poorer survival, higher cumulative incidence of events was revealed. Cox models identified AAC score ≥ 6 as an independent risk factor of cardio-cerebrovascular mortality (AAC score ≥ 6 vs. AAC score = 0: Hazard ratio: 2.38, P = 0.008) after adjusting for cardiovascular risk factors. Results remained significant after regrouping (AAC score ≥ 6 vs. AAC score < 6: Hazard ratio: 2.06, P = 0.016). Subgroup analysis provided no evidence of unparallel change in hazard for the same amount of increase in AAC score among middle-aged (40-65 years old) and elderly (≥ 65 years old) individuals.

Conclusions: AAC score ≥ 6 independently indicate increased risk of cardio-cerebrovascular death and would be effective in risk stratification among the general middle-aged and elderly population in clinical practice.