CT for Hematuria Evaluation Does More Harm Than Good

Veronica Hackethal, MD

July 30, 2019

Some guidelines recommend using CT in the initial evaluation of patients who have blood in their urine, but a study suggests that the harms of doing so may outweigh the benefits of early diagnosis. Results were published online on July 29 in JAMA Internal Medicine.

The researchers used a computer simulation model to compare diagnostic accuracy, harms, and costs for five topline guidelines for the initial evaluation of hematuria.

Although CT was associated with marginal improvement in the detection of urinary tract cancers, radiation exposure during the test was associated with increased risk for cancer. The researchers estimated that the number of patients who developed CT-related cancers was approximately five times higher than that for ultrasound, which does not involve use of radiation.

Costs were twice as high with CT compared with other types of imaging, and procedural complications and false positive results were also increased.

"The balance of harms, advantages, and costs of hematuria evaluation may be optimized with risk stratification and more selective application of diagnostic testing in general and computed tomography imaging in particular," write Mihaela V. Georgieva, PhD, University of North Carolina, Chapel Hill, and colleagues.

Urologists evaluate approximately two million Americans each year for hematuria. Current guidelines differ on the initial approach for evaluating patients with blood in their urine. Some guidelines recommend ultrasound alone, whereas others recommend a combination of cystoscopy, CT, and ultrasound.

In the past 2 decades, the number of CT evaluations conducted per year in the United States has tripled. The increase has led to concern that too many patients are being exposed to potential harms from unnecessary imaging. These harms include increased risk for certain cancers as a result of radiation from CT, as well as increased costs, false positive results, and adverse events, such as urinary tract infection, allergic reaction, and kidney damage from CT contrast.

The researchers used a computer-generated microsimulation model to compare the following five guidelines for the initial evaluation of hematuria: Dutch, Canadian Urological Association (CUA), Kaiser Permanente (KP), Hematuria Risk Index (HRI), and American Urological Association (AUA).

Major differences between these guidelines include the following:

  • Cystoscopy and ultrasound in patients aged 50 years or older in the Dutch guidelines, or aged 40 years or older in the Canadian (CUA) guidelines;

  • A combination of cystoscopy, ultrasound, and CT, decided on the basis of patient risk factors for cancer, in the KP and HRI guidelines; and

  • Cystoscopy and CT for all patients aged 35 years or older.

The investigators compared these guidelines using a simulated group of 100,000 patients with microscopic and gross hematuria who were aged 35 years or older. Data for this group came from the two largest prospective studies of patients with hematuria in the United States and the United Kingdom. The researchers structured other parts of the model using real-world data from the National Academy of Sciences, the Agency for Healthcare Research and Quality, and large meta-analyses.

Results suggest that 3.5% (95% confidence interval, 3.0% – 4.0%), or 3514 of the persons in the hypothetical group of 100,000 patients, would have urinary tract cancers.

Cancer detection increased with more intensive use of CT, but differences were relatively small. The highest rate of detection was through use of the AUA guidelines, at 97.7% (n = 3432), followed by the HRI guidelines, at 96.7% (n = 3399); KP, at 96.3% (n = 3385); CUA, at 95.1% (n = 3343); and the Dutch guidelines, at 92.9% (n = 3263).

The fewest cancers were missed with use of the AUA guidelines, at 2.3% (n = 82), followed by HRI, at 3.3% (n = 116); KP, at 3.7% (n = 130); CUA, at 4.9% (n = 172); and the Dutch guidelines, at 7.1% (n = 251).

On the other hand, both the CUA and KP guidelines recommend against first-line use of CT, and use of each led to 0 predicted radiation-induced cancers. Predictions for these types of cancers numbered 108 for the KP guidelines, 136 for the HRI guidelines, and 575 for the AUA guidelines.

Use of the AUA guidelines yielded the most false positives (n = 22,189) and short-term complications associated with CT (n = 17,637). The Dutch guidelines yielded the fewest false positives (n = 6452) and the fewest complications (n = 7999).

Costs were estimated using Medicare data. Costs with use of the AUA guidelines were about twice as high as costs with use of the Dutch guidelines, which had the lowest costs ($939/person and $443/person, respectively).

"We applaud Georgieva et al for their thoughtful approach to comparing the current guidelines for initial hematuria evaluation; we believe this study sets a good example for future guidelines development," write Scott R. Bauer, MD, and colleagues from the University of California, San Francisco, in an invited commentary.

They go on to say that not all clinicians are aware that the harms of medical tests may outweigh the benefits of earlier diagnosis and treatment. For that reason, providers should consult evidence-based guidelines that have been developed to maximize overall advantages.

The commentators mention that there is a need for more research comparing guidelines for the initial evaluation of gross hematuria.

"The best available evidence suggests that uniform use of CT for the initial evaluation of microscopic hematuria is ill advised and should be replaced with risk-based approaches and increased use of renal ultrasonography. Furthermore, all guidelines should consider harms, costs, and advantages," the commentators write.

The study has several potential limitations. It did not include modeling for cancer stage, grade, site, or risk group. Likewise, the researchers did not include estimates for incidental findings, which may increase patient anxiety, costs, and the need for additional testing or procedures. That, combined with the burden of additional treatment for CT-related cancers, may further increase the costs and harm related to excess CT testing, according to the authors.

The study was funded in part by the University Cancer Research Fund, which was provided by the State of North Carolina via the University of North Carolina Lineberger Comprehensive Cancer Center. One or more authors report receiving grants or consultant fees from or advisory board membership of one or more of the following: Pfizer, Intuitive Surgical, Terumo, the National Institutes of Health, Patient-Centered Outcomes Research Institute, Agency for Healthcare Research and Quality, and American Cancer Society, the American College of Physicians High Value Care Task Force, and Grand Rounds. Bauer and Peter R. Carroll, MD, MPH, have disclosed no relevant financial relationships. Deborah Grady, MD, MPH, is deputy editor of JAMA Internal Medicine.

JAMA Intern Med. Published online July 29, 2019. Full text, Commentary

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