Lack of Benefit of Routine Serum Laboratory Control Samples during Treatment of Diabetic Foot Infection

Author(s): Pascal R. Furrer, Madlaina Schöni, Felix WA. Waibel, Martin C. Berli, Benjamin A. Lipsky, ?lker Uçkay

Purpose: Clinicians often routinely order measurements of serum inflammatory and other laboratory markers to assess the response to treatment of diabetic foot infections (DFI). Scientific evidence supporting this widespread practice is very limited and unclear. We sought to determine if the levels (or their dynamic change) of these markers predict important future outcomes, including recurrence of infection and development of foot ischemia

Methods: At Balgrist University Hospital we keep a registry of patients treated for diabetic foot diseases. This allowed us to compare, at study enrolment and at the end of treatment of a DFI, the patient’s blood levels of: C-reactive protein; leukocytes; thrombocytes; and, hemoglobin.

Results: Among 1,013 DFI episodes (patients median age 67 years, 78% male), 882 (87%) of which involved bone and the other 131 only soft tissues. Overall, we noted remission in 758 DFIs (75%), while combined surgical and medical therapy failed to control infection in the remaining 225. The incidence of infection recurrence with a microbiologically-identical strain was 5%. In crude comparisons, as well as by case-mix adjustment using a multivariate Cox regression analysis, none of the laboratory parameters was predictive of the likelihood of overall clinical failure or microbiological recurrence. The relative decrease in the level of each parameter was similar between DFI episodes with clinical remission or failure, with the exception of a moderate increase in the final thrombocyte counts among failing episodes.

Conclusions: This retrospective review of our results suggests that routine blood sampling of infection markers during DFI therapy is not beneficial for assessing key clinical outcomes.