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Guidance needed to improve utility of procalcitonin tests
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WASHINGTON, D.C. — Provider education and interpretive algorithms are necessary for procalcitonin tests to have clinical usefulness in determining whether to continue antibiotics in patients, according to data presented here at ICAAC 2014.
“Our institution rolled out the procalcitonin assay test without any formal guidance, and we found that many of our physicians and residents didn’t really know how to interpret the results,” Meenakshi Ramanathan, PharmD, assistant professor at the University of North Texas System College of Pharmacy, told Infectious Disease News. “The test had a high positive predictive value in our clinical setting, but its use was inconsistent with established guidelines.”
Meenakshi Ramanathan
Ramanathan and colleagues used retrospective data to evaluate 171 consecutive patients with a total of 402 procalcitonin tests from Jan. 1, 2013 to Aug. 31, 2013 at the Veterans Affairs North Texas Health Care System. They identified patterns of test ordering and then assessed whether the physicians adjusted antimicrobial use in concordance with a proposed procalcitonin algorithm. Published guidelines suggest that a procalcitonin level of less than 0.25 mcg/L is considered negative and is an indication to discontinue or deescalate antimicrobial use.
Among the 402 procalcitonin tests, 131 were considered negative in 77 patients. Of those patients, 36 (46.8%) continued antimicrobial therapy whereas only five patients (6.5%) deescalated therapy and 13 patients (16.9%) discontinued therapy. However, when the researchers evaluated the correlation between a low procalcitonin value and infection, they found that the test had only a 49.4% negative predictive value.
“If a patient has a positive procalcitonin test, then there is most likely a bacterial infection present and the patient will need antibiotics,” Ramanathan said in an interview. “But a negative procalcitonin test should be taken with a grain of salt, and other clinical factors like white blood cell count and fever should be considered when determining appropriate therapy.”
Ramanathan said that there was no difference in outcomes, including infection rate, Charlson comorbidity rate, mortality rate, readmission, length of stay, ICU days or antibiotic days, between patients who had antibiotic discontinuation and those who didn’t. However, she said the sample size was too small to detect a significant difference. — by Emily Shafer
For more information:
Ramanathan M. D-179. Presented at: Interscience Conference on Antimicrobial Agents and Chemotherapy; Sept. 5-9, 2014; Washington, D.C.
Disclosure: Ramanathan reports no relevant financial disclosures. One researcher reports relationships with Bristol-Myers Squibb, Janssen Therapeutics, Merck and ViiV.