The Collaborative Transplant Study ( CTS ) first newsletter for 2014 (February 1 – available to CTS participants only) presents a particularly important analysis of outcomes of deceased donor kidneys between 2003 and 2012 based on the tacrolimus trough levels one year after transplantation. If the maintenance trough levels were less than 5ng/mL there was a significantly worse graft survival at 5 years compared to those with trough levels ranging from 5 to greater than 10 ng/mL. As most patients were receiving MPA as well, CTS have looked at low dose MPA versus full dose MPA and interestingly patients who received a full dose of MPA did not show that much difference in graft survival, even with a tacrolimus trough level at one year being less than 5 ng/mL. However if they were receiving a low dose of MPA results were significantly worse.
This is reminiscent of the studies from Australia many years ago comparing different doses of azathioprine with low dose steroids where inferior graft outcomes were achieved if the dose of azathioprine was less than 2mg/kg. Thus maintenance immunosuppression must be adequate to ensure long term graft survival. In time we may be able to identify with various biomarkers which patients are at risk with inadequate immunosuppression.