Abstract
Introduction Serum procalcitonin levels increase in response to bacterial infections and decrease with successful treatment. Procalcitonin can, therefore, inform decisions around antibiotic use. For adults with suspected infection, using procalcitonin to start antimicrobials is not advocated but serial testing is suggested to aid with the decision to discontinue therapy. Methods A retrospective study was performed of adults over the age of 80 years admitted on a medical ward whom had a serum procalcitonin completed between November 2022 and April 2023. Their electronic patient records were reviewed, with data collated and analysed using Microsoft Excel. Results Of 160 patients studied, median age was 85 with a median clinical frailty score of 6. The suspected sources of infection for the patients were chest (65%), unknown source (22.5%), urine (5%), cellulitis (3%), biliary (1.3%), osteomyelitis (1.25%), abdomen (0.63%) and infected haematoma (0.63%). Confirmed viral respiratory infection was present in 76 (47.5%) patients. Of all patients, only 62% were taking antibiotics at the time the procalcitonin was taken. Only 4 patients (2.5%) had serial procalcitonin testing (24-48 hours apart). Conclusion Procalcitonin was more likely to be used for suspected respiratory tract infection than other suspected infections. The majority of patient were taking antibiotics at the time the test was performed, which would indicate the tests being used to support a diagnosis of bacterial infection. Only a minority of patients (2.5%) had more than one procalcitonin result indicating that the clinical utility of this blood test to aid decision making in altering antimicrobial therapy was not occurring. Therefore, procalcitonin testing within an older adult population is being used in an inappropriate manner in the context of infection. Given a cost of £39.50 per test we anticipate that in its current use procalcitonin testing is not being used in a cost effective or clinically effective manner.