*Purpose: To perform an economic evaluation of protocol biopsies in kidney transplantation

*Methods: We used a Markov decision analytical model (Figure 1) to compare the following strategies for detecting sub-clinical rejection (SCR) in the first year after kidney transplantation (KT): no protocol biopsy (PB), PB at 3 months, PB at 12 months, PB at 3 and 12 months and PB at 3, 6 and 12 months. Costs, utilities and probabilities were derived from published reports (select base case values are shown in the table). Key model inputs and assumptions were: 1) Both sub-clinical T-cell mediated rejection (SC-TCMR) and sub-clinical antibody mediated rejection (SC-ABMR) were included 2) All SCR episodes were treated 3) 50% of SCR occurred between 0 and 3 months and 50% occurred between 3 and 12 months after KT. 4) Biopsy had 100% sensitivity and specificity for detecting SCR. A lifetime analysis was performed. Incremental cost effectiveness ratios (ICERs) were calculated for each strategy, and one-way sensitivity analysis were performed.

*Results: On base case analysis, ICER for 12-month PB over no PB was $37,660 per quality adjusted life year (QALY) gained. 3-month PB yielded lower QALYs than 12-month PB at higher cost. QALY gains from increasing PB frequency during first year were small and resulted in high ICERs ($186,862 for PB at 3 and 12 months, and $272,978 for PB at 3,6 and 12 months). Table 3 shows the results of one-way sensitivity analysis of PB at 12 months over a no PB strategy. Results were most sensitive to patient age, and relative risk (RR) for graft failure from SC-TCMR and SC-ABMR. Cost-effectiveness worsened with increasing patient age and lower RR for graft failure from SC-TCMR and SC-ABMR. Results were also sensitive to biopsy cost, prevalence of SCR, and SCR treatment efficacy.

*Conclusions: In kidney transplantation, protocol biopsy more than once during the first year is not economically reasonable. Cost-effectiveness varied significantly with age, biopsy cost, SCR treatment efficacy, and SCR impact on graft survival.

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