More than 3% of prostate biopsies subject to errors

More than 3% of prostate biopsies are subject to medical errors or contamination, a recent study found.

More than 3% of prostate biopsies are subject to medical errors or contamination, a recent study found.

The study, published online in the American Journal of Clinical Pathology (2013; 139:93-100), found that up to 3.5% of patients initially diagnosed with cancer were subject to undetected specimen switches or contaminations that may have compromised the accuracy of their diagnosis.

The study examined the actual rate of occult specimen provenance complications (SPCs) among 13,000 prostate biopsies processed in more than 50 pathology labs, for which DNA specimen provenance assignment (DSPA) testing was performed as part of routine clinical care. Each of the SPCs was classified as either a type 1 error (a complete transposition between patients) or type 2 error (contamination of the patient’s tissue with one or more unrelated patients).

Study authors, led by John Pfeifer, MD, PhD, of Washington University in St. Louis, observed that the mean percentage of undetected SPCs across all practice settings was 0.22% for type 1 and 1.69% for type 2 provenance errors, with a combined SPC rate as high as 3.51% measured in certain settings.

"The potential for misidentification of a patient’s biopsy results is a real concern in anatomic and clinical pathology with potentially devastating consequences," Dr. Pfeifer said. "While many physicians have long suspected that specimen provenance complications occur, these results provide the first estimate of their frequency."

In a related study published in Value in Health (2012; 15:860-7), Dr. Pfeifer and colleagues concluded that DSPA testing is likely a cost-effective method for preventing treatment errors resulting from biopsy misidentification.

This study used a decision-analytic model developed to compare DSPA testing of cancerous prostate biopsy specimens with the alternative of performing prostate biopsies with no provenance testing. Parameter values were chosen from published literature to calculate the expected costs of misdiagnosis and incremental cost effectiveness of DSPA testing to avoid misdiagnosis.

Results indicate that given certain conservative assumptions regarding the hypothetical rate of provenance errors and the price of DSPA analysis, testing of positive biopsy samples to rule out the presence of occult SPCs is likely a cost-effective method for improving patient outcomes, researchers reported.

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