The relative benefits and costs of solid phase bead technology to detect preformed donor specific antihuman leukocyte antigen antibodies in determining suitability for kidney transplantation.

BACKGROUND: Screening for donor-specific anti-HLA antibodies (DSA) using bead-based multiplex assays to determine transplant suitability is standard practice in many countries. We compared the health benefits and costs of screening preformed DSA using bead-based assay as an add-on test to complement-dependent cytotoxicity (CDC) crossmatch with CDC crossmatch alone, and determined the optimal threshold to determine transplant suitability. METHODS: Three probabilistic Markov models were developed to compare bead-based assay with CDC and CDC alone. The model assumed a hypothetical cohort of 10,000 patients who received only a single kidney transplant and terminated when all patients were deceased. RESULTS: Assuming transplantation was permitted for recipients with no DSA or with a DSA mean fluorescence intensity (MFI) value of 500 or less, screening by bead-based assay and CDC saved 6.5 grafts and U.S. $1,192,303 per 100 transplants compared with CDC alone. If the thresholds were increased to an MFI of 2000 or less and 5000 or less, an extra 6.4 and 6.1 grafts would be saved, with cost savings of U.S. $867,203 and U.S. $830,664 per 100 transplants compared with CDC alone. The total number of kidney transplants performed would have increased by 8 and 9, respectively, but at the expense of an extra 0.1 and 0.4 graft lost per 100 transplants after 5 years. CONCLUSIONS: Screening using bead-based assay is cost-saving and improves graft outcomes. The greatest benefits and cost-savings are achieved if transplantation occurs at a threshold of MFI of 500 or less or in those without preformed DSA. Increasing the threshold to an MFI of 2000 or less may provide an acceptable balance for improving transplant eligibility without compromising longer-term outcomes.

The impact of abnormal glucose regulation on arterial stiffness at 3 and 15 months after kidney transplantation.

BACKGROUND: Post-transplant diabetes mellitus (PTDM) has been associated with an increased risk of cardiovascular disease (CVD) mortality following kidney transplantation, but the association between pre-diabetes (i.e. impaired fasting glucose and impaired glucose tolerance) and CVD mortality remains unclear. The aim of this study was to assess the association between abnormal glucose regulation and arterial stiffness at 3 and 15 months post-transplantation. METHODS: This is a single-centre prospective cohort study of 83 non-diabetic kidney transplant recipients who received a kidney transplant between 2008 and 2011. All patients underwent an oral glucose tolerance test (OGTT - categorised as normal, pre-diabetes or PTDM) and non-invasive measurements of arterial stiffness (aortic pulse wave velocity [PWV] and augmentation index [AIx]) 3 months post-transplantation. A sub-set of patients had repeat OGTT (n = 33) and arterial stiffness measurements (n = 28) at 15 months post-transplant. RESULTS: Of the 83 patients, 52% (n = 43) had normal glucose regulation, 31% (n = 26) had pre-diabetes and 17% (n = 14) developed PTDM. Compared with recipients with normal glucose regulation, recipients with PTDM (adjusted ß = 5.61, 95% confidence interval [CI] 0.09 to 11.13, p = 0.047) but not those with pre-diabetes (adjusted ß = 3.23, 95% CI -1.05 to 7.51, p = 0.137) had significantly higher AIx 3 months after transplantation. No association was found between glucose regulation and PWV at 3 months after transplantation. There was no association between glucose regulation at 3 or 15 months and AIx and PWV at 15 months in a subset of recipients. CONCLUSIONS: Early onset PTDM is associated with increased systemic vascular stiffness (AIx) but not regional stiffness of large arteries (PWV) suggesting that small vessel dysfunction may be the earliest vascular change seen with PTDM. Thus, measurements of arterial stiffness after transplantation may assist in more accurately stratifying future CVD risk of kidney transplant recipients.