A recent study of patients with a new diagnosis of microhematuria finds that rates of bladder and kidney cancer as well as urolithiasis depend on how thoroughly the patients are evaluated.
The AUA guidelines for microhematuria are broad because there’s little known about how best to determine who needs costly evaluations. Now, a study suggests urologists will be able to use the degree of microhematuria and the number of positive samples to determine whether patients should get further workups.
“Our data is proof our patients have identifiable characteristics that put them at higher risk for kidney/bladder cancer or stone disease. Our goal is to provide better evidence about who should have further diagnostic testing, which includes imaging and cystoscopy,” said lead author Richard Matulewicz, MD, MS, of McGaw Medical Center of Northwestern University, Chicago.
At issue: How should urologists evaluate microhematuria?
“Though the definition of abnormal microhematuria has changed over the years, past health screening studies have estimated that between 2% and 30% of adults have microhematuria. Higher rates are seen in older people and smokers. Urologists see many of these patients, and very few have a urologic condition,” Dr. Matulewicz told Urology Times.
However, AUA guidelines suggest that adult patients undergo evaluations when microhematuria-three or more red blood cells on a single urinalysis-occurs without an obvious benign etiology like a urinary tract infection or trauma, said co-author Joshua Meeks, MD, PhD, of Northwestern University Feinberg School of Medicine, Chicago.
“The AUA microhematuria guidelines are broad because they are based on the best evidence currently available,” Dr. Meeks told Urology Times. “For example, to date there has not been a minimum number of red cells that are most predictive of identifying bladder cancer.”
In the new study, presented at the AUA annual meeting in San Diego, the authors examined a hospital system database of 11,902 patients with a new diagnosis of microhematuria from 2008-2011.
The patients were 71% female, 48% Caucasian, 22% African-American, 4% Hispanic, 3% Asian, and 22% unknown. They were followed indefinitely-a median of 5.8 years-for diagnosis of bladder cancer, kidney cancer, and urolithiasis.
Sixty-one percent of patients had an initial urinalysis of 3-10 RBC/hpf, and 10,254 (35.2%) had at least one more urinalysis in the 6 months after initial diagnosis.
Next: What the authors found
The authors found that the rates of bladder and kidney cancer as well as urolithiasis depended on how thoroughly the patients were evaluated. In those who had a complete workup (cystoscopy and imaging), the rates of diagnosis were 4.7%, 3.1%, and 16.5%, respectively for bladder cancer, kidney cancer, and urolithiasis.
Higher levels of blood in the urine on the first urinalysis, especially >100 RBC/hpf, were linked to higher risk of these conditions. Also importantly, men and older patients were found to be at highest risk for malignant diagnoses.
The authors say their findings shouldn’t change practice now. But the research is serving as proof of concept and pilot data for a combined quality improvement/research endeavor that’s been funded through the 2016 Clinical Care Innovation Pilot award from the American Association of Medical Colleges, Dr. Matulewicz said.
The funding will support the development of a learning health system module for implementation into the electronic medical record at Northwestern.
“This platform will collect granular data on our microhematuria patients’ risk factors, urinalysis details, and workup findings/outcomes,” Dr. Matulewicz said. “Further, our research demonstrated that very few-roughly 10%-of patients had a complete hematuria evaluation. This may be due to the complexity of care coordination associated with a complete evaluation, so in addition to collecting data prospectively, we plan to integrate a microhematuria ‘dashboard’ for internists. This will ensure that a patient’s complete evaluation is performed after they are seen in their primary care physicican’s office.”
“We hope to use this information to develop a robust risk-stratification model and eventually a risk calculator to be used at the point of care to help urologists and their patients have a shared decision-making discussion about undergoing an evaluation,” Dr. Matulewicz added.
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