MP522CORRECTED SERUM CALCIUM AS A PREDICTIVE FACTOR FOR ABDOMINAL AORTA CALCIFICATION IN CKD PATIENTS ON DIALYSIS

Abstract

Introduction and Aims: Presence and severity of cardiovascular calcification are associated with poor outcomes in chronic kidney disease (CKD) patients. The aims of this study were to determine the prevalence of abdominal aortic calcification and the predictive factors of vascular calcification in Thai dialysis and non-dialysis CKD patients. Methods: In this cross-sectionally study, patients were consecutively enrolled across 25 sites in Thailand until 1500 enrollments. Adult CKD patients (≥18 and ≤70 years) confirmed with a minimum 3 months prior to the evaluation as stage 3-5 (dialysis or non-dialysis) with signed informed consent form were eligible for inclusion. The exclusion criteria were 1) post-renal transplant patients; 2) pregnant women; 3) candidate not suitable for X-ray;4) patients with acute kidney injury, very severe comorbidities with poor survival outcome; 5) concomitant diseases that affect calcium status and soft tissue calcifications; 6) patients who received parathyroidectomy. The primary evaluation was abdominal aortic calcification which was assessed by a validated 0-24 abdominal aorta calcification (AAC) score on lateral abdominal radiographs. Predictive factors for the AAC score ≥ 5 were analyzed with multi-variable logistic regression analyses. Results: A total of 1,500 patients (55.4% male, mean age 54.7 (SD 11.4) years) from 24 study sites were included, of whom 814 (54.3%) and 686 (45.7%) were pre- and ongoing dialysis, respectively. The prevalence of AAC as judged from AAC score ≥ 1 was 70.6 % (95% CI: 67.4% - 73.7%) and 70.8% (95% CI: 67.3% - 74.1%) for pre- and ongoing dialysis patients, respectively. Thirty-one percent overall had AAC ≥ 5. Predictive factors for the AAC score ≥ 5 for pre-dialysis pateints are advanced patient's age and widening pulse blood pressure (odds ratio (OR): 1.115 and 1.017, with p < 0.01 and 0.013 respectively). For patients on dialysis, the predictive factors were advanced patient's age, history of coronary artery disease or diabetes, long dialysis vintage (OR: 1.083, 2.956, 1.852 and 1.008, all with p < 0.05), and most strikingly, corrected serum calcium and hs-CRP (with OR: 1.468, and 1.223, both with p < 0.01, respectively). In order to explore clinically meaningful information, a series of regression analyses were performed with different corrected serum calcum cut-offs. The results showed a peaked odds ratio of 1.974 (95% CI: 1.324 - 2.943) for the corrected serum calcium cut-off at 9.5 mg/dL. In additional subgroup analysis of patients with diabetes (n = 692), 1,25 (OH)2 vitamin D was found to be a protective factor for AAC (OR 0.983, p = 0.0104), while serum phosphorus was found to be another predictive factor for AAC (OR 1.178, p = 0.0153). Conclusions: Prevalence of AAC in Thai CKD patients has been reported. Most variables identified as predictive factors for AAC are consistent with the findings from previously studies. However, the corrected serum calcium was identified as another predictor of abdominal aorta calcification in this study.