Determination of the factors affecting egfr slope during the first two years of renal transplantation in renal transplantation patients

Aim: Determination of the factors affecting eGFR slope during the first two years of renal transplantation in renal transplantation patients with regular outpatient clinic control. Findings: Fifty nine renal transplantation patients who completed the first two-year regular follow-up period after transplantation in the Nephrology Department of the Internal Medicine Department of Inonu University Medical Faculty were included into the study. We collected baseline characteristics and laboratory results such as age, gender, ethnicity, cause of end stage renal failure, transplantation and 2 years laboratory data such as hemoglobin, leukocyte, thrombocyte, serum glucose, Blood urine nitrogen (BUN), creatinine, BK virus and cytomegalovirus (CMV) polymerase chain reaction (PCR) retrospectively from the computerized patient record system. Clinical practice guidelines for K/DQI indicate that GFR decreases by 1 ml/min/year after reaching a peak level of 125 ml/min in adulthood (30-40 years) in normal individuals. For each patient, the eGFR decline rate (slope) (mL/min-1/1.73 m2 -1/year-1) was determined by linear regression analysis using all calculated eGFR values over the study period. The K/DQI clinical practice guidelines suggest that, in normal individuals, GFR decreases by 1 ml/min/year after a peak level of 125 ml/min has been reached in adulthood (30–40 years). Therefore, any reduction greater than this is considered to be a progressive slope (slope more negative than -1 ml/ min/year (-1), stable ([-1 to +1), or an improved slope if it shows more of an increase, i.e., greater than +1.0 ml/min/year). Material and methods: Of 59 patients, 7 (11.8%) had a progressive slope, 22 (37.2%) stable slope, 30 (50.8%) improved slope. Mean eGFR slope was 1.28 ± 2.5 ml/min/year. The mean age of patients with progressive slope (32.1 ± 12.8 years) was lower than those of patients with stabile slope (47.6 ± 12.2 years) and those with an improved slope (42.8 ± 11.5 years) (P= 0.014). In patients with progressive slope mean serum kreatinin levels (1.8 ± 0.5 mg/dL) was higher than those of patients with improved slope (1.3 ± 0.3 mg/dL) (p=0,013). eGFR slope was -3.02 ± 1.7 mL/mean/year in patients with progressive slope, 0.1 mL /min /year in patients with stabil slope and 3.1 ± 1.7 mL /min /year in patients with improved slope ( p= 0.000). The first year mean tacrolimus level was significantly lower in patients with progressive slope (7.2 ± 1.0 ng/mL) than in the patients with stable slope (7.8 ± 1.4 ng / mL) and in the patients with improved slope (8.5 ± 0.9 ng / mL) (p= 0.022). No difference was found among slope groups according to the second year mean tacrolimus levels (p<0.05). There was a statistically significant positive correlation between mean slope and the first year mean serum tacrolimus level (r= 0.304, p= 0.024), two year mean tacrolimus level (r= 0.307, p= 0.023) and the second year mean glomerular filtration rate (r= 0.434, p= 0.001). The determinants of EGFR slope in multiple regression analysis were post transplant hypertension (β= -0.393, p= 0.002) and the first year mean tacrolimus level (β= 0.320, p= 0.010) wherase age, serum albumin, two year mean tacrolimus level did not reach the level of significance. In conclusion, we found out that tacrolimus levels in the first year, and postoperative hypertension development were the determinants of eGFR slope. It seems to be very important that keeping tacrolimus levels high in the first year to prevent eGFR declining. Keywords: Chronic renal failure, renal replacement treatments, renal transplantation, factors affecting eGFR