Elsevier

Mayo Clinic Proceedings

Volume 88, Issue 2, February 2013, Pages 129-138
Mayo Clinic Proceedings

Original article
Stratifying Risk of Urinary Tract Malignant Tumors in Patients With Asymptomatic Microscopic Hematuria

https://doi.org/10.1016/j.mayocp.2012.10.004Get rights and content

Abstract

Objective

To identify patients who could safely avoid unnecessary radiation and instrumentation after the detection of microscopic hematuria.

Patients and Methods

We conducted a prospective cohort study of patients who were referred to urologists and underwent a full evaluation for asymptomatic microscopic hematuria during a 2-year period in an integrated care organization in 3 regions along the West Coast of the United States. A test cohort and validation cohort of patients with hematuria evaluations between January 9, 2009, and August 15, 2011, were identified. Patients were followed passively through their electronic health records for a diagnosis of urothelial or renal cancer. The degree of microscopic hematuria, history of gross hematuria, smoking history, age, race, imaging findings, and cystoscopy findings were evaluated as risk factors for malignant tumors.

Results

The test cohort consisted of 2630 patients, of whom 55 (2.1%) had a neoplasm detected and 50 (1.9%) had a pathologically confirmed urinary tract cancer. Age of 50 years or older and a recent diagnosis of gross hematuria were the strongest predictors of cancer. Male sex was also predictive of cancer, whereas smoking history and 25 or more red blood cells per high-power field on a recent urinalysis were not statistically significant. A Hematuria Risk Index developed from these factors had an area under the receiver operating characteristic curve of 0.809. In the validation cohort of 1784 patients, the Hematuria Risk Index performed comparably (area under the curve = 0.829). Overall, 32% of the population was identified as low risk and 0.2% had a cancer detected; 14% of the population was identified as high risk, of whom 11.1% had a cancer found.

Conclusion

These results suggest that a considerable proportion of patients could avoid extensive evaluations with the use of the Hematuria Risk Index.

Section snippets

Patients and Methods

From January 9, 2009, to August 15, 2011, a prospective, observational cohort study was conducted within a large managed care organization (Kaiser Permanente) that provides comprehensive care for members through a capitated health plan. Most health care for members is provided in system-owned medical centers or their affiliated outpatient facilities. A small fraction of emergent and specialty care is obtained from other health care professionals through contractual arrangements or through a

Results

There were 3,222,699 urinalyses performed in 1,117,542 patients in the test cohort regions from January 9, 2009, to October 26, 2010. Of these patients, 456,674 had microscopic hematuria and 389,207 had 2 positive urinalysis results meeting the threshold for evaluation. During this period, 7778 patients were seen by a urologist for evaluation of asymptomatic microhematuria and 4721 underwent cystoscopy. The details of 2630 of those evaluations were entered into the electronic data collection

Discussion

In this prospective cohort study, we found that microscopic hematuria is an unreliable indicator of urothelial or renal malignant tumors. An extremely small proportion of patients with microscopic hematuria are subsequently found to have cancer, confirming our previous retrospective results.12 In fact, most malignant tumors can be identified by a history of gross hematuria, a far more reliable indicator of the need for urologic evaluation and imaging. This finding suggests that a large number

Conclusion

These data suggest that microscopic hematuria is an unreliable indicator of urinary tract malignant tumors. Patients with microscopic hematuria younger than 50 years and with no history of gross hematuria may not benefit from further evaluation and therefore could avoid unnecessary risk from radiation exposure and invasive endoscopy. These findings may be used to simplify referral guidelines for evaluation in asymptomatic patients with microscopic hematuria and reduce the number of unnecessary

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    For editorial comment, see page 123

    Grant Support: This study was funded from internal infrastructure from the Department of Research and Evaluation, Kaiser Permanente Southern California.

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