A widely used PSA threshold for recommending prostate biopsy (4.0 ng/mL) has remained unchanged over time despite some calls to lower the threshold, according to researchers.

Steven B. Zeliadt, PhD, of the Department of Veterans Affairs Medical Center in Seattle, and colleagues reviewed laboratory and biopsy records of 59,764 men in Group Health, a large integrated health care system in Washington State for the period 1998-2007.

The study showed that 28% of tests with PSA levels of 4.0 or above were followed up with a prostate biopsy within 12 months, the researchers reported online in the American Journal of Preventive Medicine. More than 40% of tests showing a PSA level of 4.0 or above had a urology follow up without a biopsy within 12 months, and more than 30% did not have any PSA-related follow-up within 12 months. The study also showed that 2.9% of PSA tests with levels between 2.5 and 4.0 and 0.4% of tests below 2.5 were followed with a biopsy within 12 months.

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The predicted probability of biopsy for men with a PSA level of 4.0 ng/mL or higher was 33%, 29%, and 28.3% for the periods 1998-2001, 2002-2004, and 2005-2007, respectively. Further analyses indicated no significant change in biopsy threshold during the study period.

The likelihood of biopsy was strongly associated with PSA velocity, the researchers found. Among men with PSA levels of 4.0 or higher, those with a rapidly rising PSA velocity were significantly more likely to undergo biopsy than those with a slow-growing velocity (36.9% vs. 21.7%).

“The present study highlights the importance of acknowledging that aggressiveness of biopsy is an important component of the PSA screening discussion, as even small changes in the PSA threshold can substantially alter the potential harms and benefits of screening,” the authors concluded.

In addition, Dr. Zeliadt’s group found that urologists were 13% more likely than primary care doctors to order a biopsy. The researchers explained in Group Health “it is likely that the majority of tests performed by urologists were diagnostic or related to other genitourinary conditions as men do not see urologists for routine primary care services.” Thus, the increased biopsy rate might have been due to the presence of other symptoms.