RESULTS

Among the 21,546 adult recipients of a first kidney only transplant who did not have diabetes and had Medicare as their primary payer during the study period, we excluded 1421 patients who were not prescribed a CNI or sirolimus in combination or with mycophenolate mofetil (MMF) or azathioprine (AZA), as described in the Concise Methods section. The 20,124 study patients were less likely to be of white race than excluded patients (68.5 versus 71.6% respectively; P= 0.04). Other demographic variables, including known risk factors for NOD (age, gender, Hispanic ethnicity, cause of ESRD, body mass index, hepatitis C serostatus, deceased-donor source, and corticosteroid use at time of transplantation) were similar between included and excluded patients (data not shown). Study patients were followed for a median of 2.63 yr (quartile 1, quartile 3= 1.26, 3.00). The majority of patients were prescribed a CNI in combination with MMF/AZA (Table 1). Because of the large sample size, there were a number of statistically significant differences between patients treated with different maintenance immunosuppressive drug combinations in univariate analyses (Table 1).