Effects of overhydration, Kt/Vurea, 2-microglobulin on coronary artery calcification and mortality in haemodialysis patients

Aim: We studied the effects of overhydration (OH), Kt/Vurea and beta 2-microglobulin (beta 2-MG) on coronary artery calcification and mortality in patients undergoing haemodialysis (HD). Methods: The Agatston coronary artery calcium score (CACS), postdialysis body composition using bioimpedance analysis, single-pool Kt/Vurea and predialysis beta 2-MG at baseline were assessed and followed up for 3 years in patients undergoing HD. We performed logistic regression analyses for a CACS >= 400 and Cox proportional hazard analyses for all-cause and cardiovascular mortality. Results: The study involved 338 patients with a median age of 67 (56-74) years, dialysis duration of 70 (33-141) months and diabetes prevalence of 39.1% (132/338). Patients with a CACS >= 400 (n = 222) had significantly higher age, dialysis duration, male prevalence, diabetes prevalence, C-reactive protein, predialysis beta 2-MG, OH, extracellular water/total body water and overhydration/extracellular water (OH/ECW) but significantly lower Kt/Vurea than patients with a CACS <400 (n = 116) (p < .05). OH/ECW, Kt/Vurea and predialysis beta 2-MG were significant predictors of a CACS >= 400 (p < .05) after adjusting for age, dialysis duration, serum phosphate and magnesium. In all patients, cut-off values of OH/ECW, Kt/Vurea and predialysis beta 2-MG for a CACS >= 400 were 16%, 1.74 and 28 mg/L, respectively. After adjusting for dialysis duration, OH/ECW >= 16%, Kt/Vurea >= 1.74 and beta 2-MG >= 28 mg/L were significant predictors of 3-year all-cause mortality but not 3-year cardiovascular mortality. Conclusion: Higher OH/ECW, higher predialysis beta 2-MG and lower Kt/Vurea values are significant risk factors for a CACS >= 400 and 3-year all-cause mortality in patients undergoing maintenance HD.