Better correlation of pulse wave velocity (PWV) than coronary artery calcium score (CACS) with parameters of mineral bone disturbance in chronic kidney disease (MBD-CKD)

Abstract

Introduction: The coronary artery calcium score (CACS), although frequently used as a hallmark of vascular calcification (VC) in many studies of mineral bone disturbance in chronic kidney disease (MBD-CKD), reflects primarily intimal calcification. However, VC in MBD-CKD occurs largely in the media secondary to osteogenic transformation of vascular smooth muscle cells exposed to the uremic milieu. Hence, we hypothesized that the pulse wave velocity (PWV), which reflects vascular stiffness from medial VC, might correlate with the parameters of MBD-CKD, including fibroblast growth factor 23 (FGF-23), better than does the CACS. Methods: The KNOW-CKD is an ongoing prospective, hospital-based, observational cohort study being conducted in nine major university hospitals across South Korea under the sponsorship of the Korean Center for Disease Control and Prevention. We performed a cross-sectional analysis of the relationship between indicators of VC, such as brachial-ankle PWV (baPWV) and the CACS, and parameters of MBD-CKD using the data from this cohort. The uppermost tertile value of the mean of the baPWV (MPWV) was regarded as significant arterial stiffness. Severe CAC was defined as a calcium score of ≥100 Agatston units. Results: A total of 753 adult patients were enrolled from August 2011 to November 2011

58.4% were male, and the median age was 53 years (range, 20–75 years). The prevalences of hypertension, diabetes, cerebrovascular disease, and coronary heart disease (CHD) were 89.9%, 26.3%, 7.4%, and 5.6%, respectively. In univariate analysis, both the CACS and MPWV were associated with traditional risk factors for atherosclerosis and the parameters of MBD-CKD. However, after binary logistic regression analysis, only traditional risk factors such as age, male gender, diabetes, and CHD were significant risk factors for severe CAC (p < 0.001, p < 0.001, p = 0.014, and p < 0.001, respectively). With regard to arterial stiffness, parameters of MBD-CKD, such as estimated GFR (eGFR), random urine protein-to-creatinine ratio (UPCR), and T-score of DEXA for the femur neck, were independent risk factors for significant arterial stiffness (p = 0.016, p = 0.041, and p = 0.003, respectively). We also compared the relationship between log-normalized CACS or MPWV and MBD parameters and assessed the correlation between FGF-23 and other related parameters. The MPWV showed a stronger relationship with MBD parameters than did the CACS. Furthermore, FGF-23 showed a significant association with other related parameters, such as the serum phosphorus level, corrected calcium, eGFR, UPCR, fractional excretion of phosphorus, and MPWV in the entire study population (p < 0.001, p < 0.001, p < 0.001, p < 0.001, p < 0.001, and p = 0.025, respectively). Conclusions: In this study, we compared the adequacy of the CACS and PWV for assessment of VC in MBD-CKD in a prospective observational CKD cohort. Because the PWV correlated with parameters of MBD-CKD, including FGF-23, better than did the CACS, the PWV rather than the CACS is suggested to be a marker of VC in MBD-CKD.