Graft survival prediction at short and medium term using gamagraphic indexes in renal transplant receptors

Abstract

In the survival of renal grafts there are some factors that play a role and that are identified during pre transplant assessment and the early post operative variables with which medical management options have been established to improve short and long term survival. This work includes also two gamagraphic indexes as survival predictors, the tubular injury scale TISS and renal extraction index (R20/3).

Objectives: determine TISS and R20/3 prediction value in graft's survival at six months and one year.

Site: Fundación Clínica Valle de Lili, Cali, Colombia

Design: observational study of retrospective cohort.

Materials and methods: 99mTc-Mag3 Renal scanners of renal receptors were reviewed the first week after transplant. TISS indexes and R20/3 were recorded. Clinical histories of those patients were also reviewed obtaining demographic information, organ's time of isquemia, biopsies' results, presence of acute rejections and patients' evolution. A one variance statistical analysis was made as well as survival analysis with STATA 5.0 and later on, multi-variance and survival analysis were made with the following results: 53 out of 111 studies were selected in the first week after transplant. Patients' mean age was 41.4 years (18 to 71), and 45% were women. 87% of the grafts were from cadaver donors. The average follow up time was 15 months. 17 out of 53 had graft loss. In the one variance analysis the following factors were associated with graft loss: acute rejection, acute tubular necrosis, TISS, time of isquemia for more than 18 hours and R20/3 of more than 1.57.

However, when the multi analysis, logistics regression and COX proportional analysis were performed, TISS was found to be an independent predictor (RH=2.28, IC:1.1 ­ 4.8; OR 2.67 ­ 48; OR = 2.67 IC 1.02; P<0.-05). Discriminating the degree of TISS, survival at 1, 6 and 12 months was: TISS 1, 100% TISS 2-4, 87%, 77% AND 73%, and for TISS 5-6, 22%, AND 0%. The R20/3 index was affected by the time of isquemia and was not useful as predictor.

Conclusions: the best scanner index to predict short and long term graft's survival was TISS. Grade 1 and grades 5-6 discriminated very well the graft's survival prognosis. R20/3 index is very much affected by other variables and, by itself, was not useful in predicting survival for receptors with TISS grades 2-4 and additional diagnostic method (eventually biopsy) would be required, to better define the prognosis.