TUESDAY, April 12 (HealthDay News) -- Progressive scar damage to transplanted kidneys may be less common and less severe than reported in previous research, says a new study.

The research included 797 patients who received new kidneys between 1998 and 2004 and were followed for at least five years.

One year after transplant, 87 percent of the patients had mild or no signs of progressive scar damage on their new kidney. After five years, that decreased slightly to 83 percent, said the Mayo Clinic researchers.

The investigators noted that their findings contrast with studies of patients who received kidney transplants in the early 1990s. Those earlier reports found most transplanted kidneys were affected by progressive scarring that eventually resulted in transplant failure.

"These results are significant and encouraging for everyone who is concerned about long-term survival for kidney transplant patients," transplant surgeon Dr. Mark Stegall said in a Mayo Clinic news release. "Our results suggest that transplanted kidneys may be doing better than reports from prior eras have indicated."

The study is published in the April issue of the American Journal of Transplantation.

More information

The National Kidney Foundation has more about kidney transplant.