P1840EVOLUTION OF FACTORS ASSOCIATED WITH THE DEVELOPMENT OF CALCIPHYLAXIS AFTER KIDNEY TRANSPLANTATION

Background and Aims Calciphylaxis, also known as calcific uremic arteriolopathy (CUA), is a rare and underdiagnosed condition usually associated with end-stage renal disease (ESRD), with a poor prognosis once established. Although typically related with ESRD vintage, there are some reports of CUA after kidney transplantation (KT). The development of CUA in patients with KT is uncommon, and the underlying factors for its development remain unclear. Method Revision of the factors associated with the development of CUA after KT in 37 cases, of which 8 cases were extrapolated from our local registry and 29 cases reported by the literature from 1969 to 2019. Differences between groups were analyzed with Student’s T-test and Fisher’s exact test, according to the studied variable (continuous/dichotomous). Results Demographic and baseline characteristics are displayed in Table 1. In the whole population, 52.8% of patients were men and mean age was of 46.95 ± 18.72 years. Diabetes mellitus was present in 36.4% of patients while only 5.3% were reported to be obese. Vitamin K inhibitors were used in almost half of the population (45.5%). Creatinine at diagnosis was 3.14 ± 3.63 mg/dl. Dialysis and transplant vintage were respectively 76.97 ± 141.90 and 29.54 ± 56.11 months. Mean PTH was 631.15 ± 502.64 and previous parathyroidectomy was performed in 21.6% of patients. It has to be highlighted that 28.0% of total population had PTH levels < 100 pg/ml at diagnosis. Total calcium was 9.69 ± 1.04 mg/dl and phosphorus 4.16 ± 1.51 mg/dl. Many of these factors differed greatly depending on the time period of the diagnosis (before or after 1990). Patients diagnosed before 1990 were younger than those diagnosed after 1990 (31.57 ± 10.19 years vs. 56.30 ± 16.44 years; p < 0.001). Creatinine at diagnosis was much lower in patients diagnosed before 1990 (1.44 ± 0.58 vs. 3.68 ± 4.03). Dialysis and transplant vintage were greater in cases diagnosed after 1990 (dialysis plus transplant vintage 19.87 ± 12.65 vs. 115.04 ± 174.14, p=0.02). Patients diagnosed after 1990 had higher phosphorus and lower calcium compared to the other group. The employed immunosuppression changed considerably during time, being based on azathioprine (90.9%) and prednisone (100.0%) before 1990 and on calcineurin inhibitors (76.5%), mycophenolic acid (41.2%) and/or mTOR inhibitors (41.2%) and steroids (82.4%) after 1990. The CUA treatment demonstrated great variability too. Before 1990, 76.9% of patients were submitted to therapeutic parathyroidectomy, while after 1990 it was only performed in 10.5% of patients (P<0.01). Tiosulphate was administered in 31.6% and biphosphonates in 36.8% of cases. Mortality was similar in both groups (57.1% and 52.2% for patients diagnosed before and after 1990 respectively). Conclusion Factors associated with the development of CUA after KT varied greatly during time. Patients diagnosed before 1990 were younger, with better renal function, shorter dialysis and transplant vintage, higher calcium and lower phosphorus. Parathyroidectomy was the main therapeutic option before 1990 while after 1990 treatment was multimodal.