Colonoscopies are being performed more often on healthier dialysis patients than on those with more limited life expectancies; however, overall, dialysis patients are being screened at a much higher rate relative to their life expectancy than their counterparts without kidney failure.

A new analysis reveals a relatively high rate of colon cancer screening among U.S. patients on dialysis, even though they rarely stand to benefit from such screening. The findings appear in the Journal of the American Society of Nephrology (JASN).

The American Society of Nephrology recommends against colon cancer screening among patients receiving maintenance dialysis with limited life expectancy and without signs or symptoms, because of the high rates of death among patients receiving dialysis who are not candidates for a kidney transplant.

A team led by Kirsten Johansen, MD, and Christopher Carlos, MD, from University of California, San Francisco, looked to see how many US dialysis patients aged ≥50 years were being screened and whether testing was appropriately targeted toward healthier patients on dialysis.

The investigators evaluated 469,574 Medicare beneficiaries receiving dialysis between 2007 and 2012 and ranked them according to their expected survival. Over a median follow-up of 1.5 years, 11.6% of patients received a colon cancer screening.

The healthiest quarter of patients were 1.53-times more likely to be screened than the sickest quarter of patients, and those most likely to receive a kidney transplant were 1.68-times more likely to be screened than those least likely to receive a kidney transplant.

Although screening was performed more often among healthier patients, the overall screening rate was fairly high, at a rate of 27.9 colonoscopies per 1000 person-years. This rate is over 8-times higher than the rate of 3.4 per 1000 person-years found among Medicare beneficiaries not on dialysis with similarly limited life expectancies.

“While our findings suggest that the patients with the longest life expectancy and greatest chances of receiving a kidney transplant are the most likely to be screened, there remains a substantial amount of over-screening overall among patients on dialysis,” said Johansen.

“Physicians should carefully evaluate patients’ prognoses and consider the likelihood that they will truly benefit before ordering screening tests,” said Carlos.