Association of Differential Leukocyte Count With Incident Abdominal Aortic Aneurysm Over 22.5 Years: The ARIC Study.

OBJECTIVE: Leukocytes contribute to the development of abdominal aortic aneurysm (AAA). We evaluated whether associations of differential leukocyte counts with AAA persist after accounting for traditional risk factors of AAA. APPROACH AND RESULTS: Among 11 217 adults from the Atherosclerosis Risk in Communities Study, we evaluated associations of differential leukocyte counts at baseline (1987­1989) with incident AAAs over a median follow-up of 22.5 years, using Cox proportional hazards regression. Each differential leukocyte count was categorized into 5 groups­below normal, tertiles within the normal range, and above normal, with the first tertile serving as the referent. We identified 377 incident AAAs through 2011, using hospital discharge diagnoses, linked Medicare records, or death certificates. At baseline, higher neutrophil, monocyte, and eosinophil counts were associated with higher risk of AAA, independent of smoking, other differential leukocyte counts, and other traditional risk factors. The association with incident AAA was the strongest for above normal neutrophil count, with an adjusted hazard ratio (95% CI) of 2.17 (1.29­3.64). Below normal neutrophil, lymphocyte, eosinophil and basophil counts were associated with higher risk of AAA with adjusted hazard ratio (95% CI) between 1.86 (1.04­3.35) and 1.62 (1.10­2.39). CONCLUSIONS: Higher neutrophil, monocyte, and eosinophil counts in midlife are associated with higher risk of AAA, even after accounting for traditional risk factors such as smoking, obesity, and atherosclerosis. This suggests the need to identify nontraditional risk factors and treatment strategies to mitigate the residual risk of AAA conferred by midlife inflammation. Whether immunosuppression is associated with higher risk of AAA needs further investigation.

Association of serum calcium and phosphorus with measures of left ventricular structure and function: The ARIC study.

BACKGROUND AND AIMS: Elevated serum calcium and phosphorus have been associated with increased risk of cardiovascular disorders. We evaluated whether abnormal calcium and high serum phosphorus are associated cross-sectionally with echocardiographic measures of left ventricular (LV) structure and function, as doing so may provide insight into the etiology of cardiac disorders. METHODS AND RESULTS: Included in the analysis were 5213 Atherosclerosis Risk in Communities Study (ARIC) participants who in 2011-2013 had echocardiography and serum calcium and phosphorus measurements. We evaluated the association of serum calcium (corrected for albumin) and phosphorus quintiles with measures of LV structure and function, after adjusting for other cardiovascular risk factors. Participants were on average 75.3 years old; 59.1% were female and 19.8% were African American. Mean (±SD) concentrations of calcium and phosphorus were 9.33 ± 0.38 and 3.46 ± 0.45 mg/dL, respectively. Higher calcium was associated with lower LV end-diastolic diameter (LVEDD) but greater prevalence of concentric remodeling (p-trend: 0.005 and 0.004 respectively). We observed association between high phosphorus and high septal E/e' (p-trend: 0.02). Likewise, higher serum phosphorus was associated with higher left atrial volume index (p-trend: 0.001) and LV hypertrophy prevalence (p-trend: 0.04). CONCLUSIONS: In conclusion, higher calcium was associated with more concentric remodeling but lower LVEDD, suggesting complex associations between calcium and cardiac function. Serum phosphorus was related to worse indices of LV diastolic function and LV hypertrophy, but not to LV systolic function. However, the magnitudes of association were modest, so clinical implications of these findings may be limited.