(HealthDay)—A Hematuria Risk Index could identify cancer risk among patients with asymptomatic microscopic hematuria, according to a study published online Jan. 11 in the Mayo Clinic Proceedings.
Ronald K. Loo, M.D., from the Southern California Permanente Medical Group in Los Angeles, and colleagues conducted a prospective cohort study of patients with asymptomatic hematuria who were referred to a urology consult and underwent full work-up. Electronic medical records were used to passively follow patients for a diagnosis of urothelial or renal cancer.
The researchers found that, of 2,630 patients in the test cohort, 2.1 percent had a neoplasm and 1.9 percent had a pathologically-confirmed urinary tract cancer. The strongest predictors of cancer were being age 50 years or older and a recent history of gross hematuria. Male gender was also predictive of cancer. Smoking history and 25 or more red blood cells per high powered field on a recent urinalysis were not significant predictors. These factors were used to develop a Hematuria Risk Index with an area under the receiver operating characteristic curve (AUC) of 0.809. The risk index demonstrated similar performance in a validation cohort of 1,784 patients (AUC, 0.829). Of the validation cohort, 32 percent were identified as low risk and a cancer was detected in 0.2 percent. Cancer was detected in 11.1 percent of the 14 percent of the population identified as high risk.
"These data suggest that microscopic hematuria is an unreliable indicator of urinary tract malignancy," the authors write. "These findings may be used to simplify referral guidelines for evaluation in asymptomatic patients with microscopic hematuria and reduce the number of unnecessary work-ups."