Emma Hitt, PhD

May 19, 2012

May 19, 2012 (Atlanta, Georgia) — In patients with urinary tract cancer without a history of gross hematuria, the degree of microscopic hematuria did not accurately predict the presence of cancer, according to the findings of a prospective study conducted in a managed care organization.

Ronald Loo, MD, from the Southern California Permanente Medical Group in Huntington Beach, and colleagues presented the findings in an oral podium poster session here at the American Urological Association 2012 Annual Scientific Meeting.

Hematuria can occur as a result of multiple conditions, such as urinary tract or kidney infections, kidney stones, enlarged prostate, injury, strenuous exercise, and urinary tract cancer. Commonly performed diagnostic tests include urinalysis, imaging studies with a computerized tomography scan, and cystoscopy.

According to the researchers, asymptomatic microscopic hematuria is common and, although "the incidence of urinary tract cancer (bladder, renal) is low, many patients undergo a work-up that includes hazardous radiation and cystoscopy."

The researchers previously reported a retrospective analysis of patients who underwent microscopic urinalysis over a 2-year period. "The incidence of urinary tract cancer was low (0.43%), and practice guidelines were poor in identifying patients with cancer, suggesting that many could have safely avoided evaluation with different criteria," Dr. Loo and colleagues note in their abstract.

On the basis of these findings, the researchers conducted a prospective study to identify patients with asymptomatic microscopic hematuria at risk for urinary tract cancer.

The researchers examined data from patients referred to a urologist, in a large managed care organization, for asymptomatic microscopic hematuria from January 2009 to August 2011. The goal of the study was to identify which patients could safely avoid unnecessary tests that involved radiation exposure and procedures.

A predictive model was developed with multivariable logistic regression models and was assessed using the area under the curve of the receiver operating characteristic curve. Variables included age, sex, smoking history, history of gross hematuria, and degree of hematuria.

In 4414 patients with asymptomatic microscopic hematuria, the rate of urinary tract cancer was 2.1%, (compared with the 0.43% the researchers previously found).

The variables associated with an increased risk for urinary tract cancer were an age of 50 years or older and a recent history of gross hematuria. Less predictive variables included being male and a history of smoking.

The degree of hematuria was least predictive of all the variables for the presence of urinary tract cancer.

According to the researchers, up to one third of patients with asymptomatic microscopic hematuria can safely avoid diagnostic testing for urinary tract cancer. These patients include those younger than 50 years without a recent history of gross hematuria.

"These data suggest that patients under age 50 with no history of gross hematuria (approximately one third of patients evaluated) may safely avoid unnecessary and potentially hazardous testing for asymptomatic microscopic hematuria," Dr. Loo and colleagues conclude in their abstract. "Microscopic hematuria of any degree should not be used to determine diagnostic evaluation," they add.

The study was not commercially funded. Dr. Loo has disclosed no relevant financial relationships.

American Urological Association (AUA) 2012 Annual Scientific Meeting: Abstract 62. Presented May 19, 2012.