RESPONSE LETTER TO CHRIST-CRAIN AND MÜLLER

Duration of antibiotic treatment using procalcitonin-guided treatment algorithms in older patients: a patient-level meta-analysis from randomized controlled trials

Background

Older patients have a less pronounced immune response to infection, which may also influence infection biomarkers. There is currently insufficient data regarding clinical effects of procalcitonin (PCT) to guide antibiotic treatment in older patients.

Objective and design

We performed an individual patient data meta-analysis to investigate the association of age on effects of PCT-guided antibiotic stewardship regarding antibiotic use and outcome.

Subjects and methods

We had access to 9,421 individual infection patients from 28 randomized controlled trials comparing PCT-guided antibiotic therapy (intervention group) or standard care. We stratified patients according to age in four groups (<75 years [n = 7,079], 75–80 years [n = 1,034], 81–85 years [n = 803] and >85 years [n = 505]). The primary endpoint was the duration of antibiotic treatment and the secondary endpoints were 30-day mortality and length of stay.

Results

Compared to control patients, mean duration of antibiotic therapy in PCT-guided patients was significantly reduced by 24, 22, 26 and 24% in the four age groups corresponding to adjusted differences in antibiotic days of −1.99 (95% confidence interval [CI] −2.36 to −1.62), −1.98 (95% CI −2.94 to −1.02), −2.20 (95% CI −3.15 to −1.25) and − 2.10 (95% CI −3.29 to −0.91) with no differences among age groups. There was no increase in the risk for mortality in any of the age groups. Effects were similar in subgroups by infection type, blood culture result and clinical setting (P interaction >0.05).

Conclusions

This large individual patient data meta-analysis confirms that, similar to younger patients, PCT-guided antibiotic treatment in older patients is associated with significantly reduced antibiotic exposures and no increase in mortality.

Diagnostic value of procalcitonin in acutely hospitalized elderly patients

The aim of this study was to evaluate procalcitonin as an adjunct to diagnose bacterial infections in older patients. One hundred seventy-two patients admitted to an acute-care geriatric unit during a 6-month period were prospectively included, 39 of them with an invasive bacterial infection. The best cut-off value to rule in a bacterial infection was 0.51 microg/l with sensitivity 64% and specificity 94%. The best cut-off value to rule out a bacterial infection was 0.08 microg/l with sensitivity 97% and specificity 20%. Procalcitonin was inconclusive (between 0.08 and 0.51 microg/l) for 112 admissions. Procalcitonin over 0.51 microg/l was useless 22 times out of 33 (infection already ruled in on clinical grounds) and misleading in eight of the 11 remaining cases (no infection). Procalcitonin below 0.08 microg/l was useless 23 times out of 27 (infection already ruled out on clinical grounds) and misleading in one of the four remaining cases (infection). Despite a good overall diagnostic accuracy, the clinical usefulness of PCT to diagnose invasive bacterial infections in elderly patients hospitalized in an acute geriatric ward appears to be very limited.