Study provides information about hematuria in microscopic urinalysis and urinary tract cancer

May 7 2011

Hematuria or blood in the urine may trigger a battery of tests for urinary tract cancer that are invasive and can unnecessarily expose patients to radiation, yet the procedures contribute little to the diagnosis, according to a study by Kaiser Permanente Southern California's Department of Research & Evaluation published in the May issue of the Journal of Urology.

Kaiser Permanente Southern California's current practice guidelines are the same as the recommendations of the American Urological Association. Both advise that patients should be evaluated for urinary tract cancer if they have two urinalysis tests showing microscopic evidence of blood in the urine. The standard of care includes a workup with kidney imaging, usually a multi-phase CT scan which is similar to having three x-rays, and an office-based procedure where a fiber-optic camera is used to visualize the inside of the bladder. The Canadian Urological Association also makes the same recommendations for patients over the age of 40. Neither the American or Canadian recommendations have been tested in a large population-based study. The American Cancer Society estimates that in 2010, there were 131,260 newly diagnosed cases of urinary tract cancer and 28,550 deaths from urinary tract cancer.

"Using information in our electronic medical records, we found an extremely low incidence of urinary tract cancer in patients with microscopic evidence of blood in their urine, suggesting that this radiation exposure and expensive workups may not be necessary for many of these individuals," said study lead author Howard Jung, MD, a urology fellow, and Department of Urology physician/researcher at the Kaiser Permanente Los Angeles Medical Center in California.

The purpose of this population-based study was to determine the proportion of patients with hematuria who were ultimately diagnosed with urinary tract cancer and to establish the risk of cancer by age, sex, and degree of hematuria. For the study, the electronic medical records of 309,402 health plan members with microscopic hematuria or blood in the urine on microscopic urinalysis during 2004 and 2005 were reviewed through 2008 to determine who was diagnosed with urinary tract cancer by 2008.

The incidence of urinary tract cancer over three years was 4.3 per 1,000 patients with hematuria. "We found that patients who were older, male, and with more red blood cells in a high-powered microscopic field were much more likely to develop urinary tract cancer," said Dr. Jung. "Compared to the American Urological Association approach, an alternative approach of only evaluating patients over the age of 40 years with at least one urinalysis with 25 red blood cells in a high-powered microscopic field would have spared 25,917 evaluations with their use of radiation, as well as have detected 6 more cases of urinary tract cancer. Compared to the Canadian Urological Association approach, it could have spared 11,584 evaluations, while detecting 16 more cases of urinary tract cancer.

"This study provides important real-world information about the association of hematuria in microscopic urinalysis and urinary tract cancer," said Dr. Jung. "Rigorous protocols are needed to re-evaluate the best policy recommendations, and target specific populations that are at risk of being diagnosed with urinary tract cancer." Kaiser Permanente is planning to continue this research with a prospective study.