Prevalence and influencing factors of peritoneal calcification in patients with long peritoneal dialysis duration

Abstract

Objective To investigate the prevalence and related factors of peritoneal calcification in peritoneal dialysis (PD) patients with long dialysis duration, and to explore the relationship between peritoneal calcification and vascular calcification. Methods This cross-section study enrolled PD patients who had received PD for more than 4 years in Peking University People's Hospital. Peritoneal calcification and abdominal aortic calcification were reviewed by CT scan. Demographic data, clinical characteristics, laboratory data including calcium phosphorus metabolism indexes (Ca, P, ALP and iPTH) and PD adequacy were collected. The influencing factors of peritoneal calcification were analyzed by Logistic regression analysis. The correlation between peritoneal calcification and abdominal aortic calcification were tested by Spearman correlation analysis. SPSS 19.0 was used for statistical analysis. Results (1) Seventy-nine PD patients were enrolled: 32 males (40.5%); mean age was (58.7±13.1) years and average PD duration was 77.25(58.00, 88.00) months. The major primary diseases were glomerulonephritis (46.8%) and diabetic nephropathy (30.4%). (2) 6 patients (7.6%) had CT-detectable peritoneal calcification. 77(97.5%) patients were found with various degrees of peritoneal thickening. The prevalence of peritoneal calcification was 7.6% in patients with PD duration more than 4 years, 10.3% in patients with PD duration more than 6 years, 18.8% in patients with PD duration more than 8 years and 40.0% in patients with PD duration more than 10 years, showing an increasing trend. Compared with non-peritoneal calcification group, the patients in peritoneal calcification group received higher doses of Vitamin D (P<0.001) and lower triglyceride levels (P=0.041). The patients were divided into two groups according to whether dialysis duration was longer than 9 years, and the proportion of patients with long PD duration in peritoneal calcification group was higher (P=0.013). Logistic regression analysis showed that PD duration, calcium and phosphorus metabolism indexes were not independent risk factors of peritoneal calcification. High vitamin D dose was an independent risk factor for peritoneal calcification (B=2.667, OR=14.394, 95% CI 1.655 - 125.165, P=0.016). (3) 74 patients were found with abdominal aortic calcification in different degrees, and the prevalence rate of abdominal aortic calcification was 93.7%. Spearman correlation analysis showed that there was no correlation between peritoneal calcification and vascular calcification (r=0.70, P=0.542). Conclusions The prevalence of peritoneal calcification in long PD duration patients is low. Peritoneal calcification may be associated with high Vitamin D dose and long PD duration. Key words: Peritoneal dialysis; Calcinosis; Vascular calcification; Long dialysis duration