Solitary renal allografts demonstrate fewer, less severe, and less progressive chronic histologic changes one and five years after transplantation than previously reported, according to the first long-term study of its kind.

“These results are significant and encouraging for everyone who is concerned about long-term survival for kidney transplant patients,” said lead investigator Mark Stegall, MD, a transplant surgeon at Mayo Clinic in Rochester, Minn. “Our results suggest that transplanted kidneys may be doing better than reports from prior eras have indicated.”

Dr. Stegall and his colleagues examined the prevalence and progression of histologic changes using protocol allograft biopsies at one and five years after solitary kidney transplantation in patients treated between 1998 and 2004. A total of 797 patients were followed for at least five years.

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The researchers found that 87% of patients had mild or no signs of progressive scar damage to the transplanted organ when biopsied at one year post-transplant. This number decreased only slightly to 83% at the five-year mark. In contrast, studies of patients transplanted in the early 1990s suggested that a majority of transplanted kidneys were affected by progressive scarring that ultimately led to failure of the transplant. 

In a subgroup of 296 patients who underwent biopsies at one and five years, mild fibrosis was present at one year and this progressed to more severe forms at five years in 23% of allografts.  Among these patients, 47% had minimal fibrosis and 40% had mild fibrosis one year post-transplant. At five years post-transplant, the numbers changed slightly, with 38% showing minimal fibrosis and 45% showing mild fibrosis. 

The results, which were published in the American Journal of Transplantation (2011;11:698-707), were similar for kidneys harvested from living and deceased donors.