The utility of cytodiagnostic urinalysis as a tool to diagnose kidney allograft dysfunction in the era lymphocyte-depleting induction therapy

Abstract

Cytodiagnostic urinalysis (CDU) has been used to evaluate causes of kidney allograft dysfunction, such as an acute rejection episode (ARE), calcineurin inhibitor (CNI) toxicity, or polyoma virus infection. We examined the concordance between CDU and allograft biopsy in patients with allograft dysfunction. Between 2002 and 2006, 201 patients had CDU performed within 7 days of a biopsy. The cohort was black (73%) with, male preponderance (59.2%), and an overall mean age of 48±13 years with 46% having received a deceased donor kidney. The induction regimen consisted of either antithymocyte globulin or alemtuzumab. CDU results that demonstrated 5 to 10 lymphocytes per high-power field (HPF) and >20 lymphocytes/HPF had 2.5 increased odds of predicting acute rejection (AR) on biopsy (odds ratio [OR] 2.5; 95% confidence interval [CI] 1.12-5.79; P=.025). In the era of antithymocyte globulin induction, a CDU result demonstrating>5 lymphocytes/HPF had a 4.3 increased odds of predicting AR (CI 1.76-10.50; P=.001). This association was lost with alemtuzumab induction. A positive CDU result for calcineurin inhibitor (CNI) toxicity did not predict CNI nephrotoxcity on biopsy, but a positive CDU for polyoma virus infection predicted polyoma virus nephropathy (OR 22.18; CI: 4.41-111.63; P<.001). In conclusion, CDU is an adjunctive diagnostic tool for kidney transplantation.