Using C-reactive protein values in patients with DFU infections to guide treatment
Patients with diabetic foot ulcer infection with lower C-reactive protein (CRP) values are at lower risk of adverse outcomes, according to research which set out to examine whether CRP could be used to determine the best point of discharge for hospital patients admitted with infected DFUs.
CRP has been used as a measure of infection progress and prognosis in people with DFU but has not been used directly to guide treatment.
The retrospective audit looked at data from 198 admissions of 105 people with diabetes admitted to and discharged from one hospital from September 2019 to December 2021 with CRP measurements and follow up for 12 weeks.
Adverse outcomes were classed as readmission, amputation or death, with these outcomes grouped according to discharge CRP from 5 to 25mg/l. A second cohort of 58 admissions in 30 patients was used to determine if outcomes could be improved.
The authors reported the following findings: “In cohort one, a total of 56 people were admitted once only and 49 more than once. The median admission CRP was 83 (IQ range 27–196mg/l) and the median discharge CRP was 15 (IQ range 7–38mg/l). Any discharge CRP over 5mg/l was associated with an increased risk of adverse outcome, OR 4.3 (95%CI 1.2–1.9) to 6.6 (CI 3.5–6.6) all p=.01, however, patients who were discharged with a CRP of >10mg/l were significantly more likely to have an adverse outcome, OR 14.4 (CI 6.6–31.4, p<.0001).
“In cohort two, 18 people were admitted once only and 12 were admitted more than once. The median admission CRP was 99mg/l and on discharge 6mg/l. Using a discharge CRP value of 11 or above mg/l as a cut-off resulted in an odds ratio of 17.9 (95% CI: 4.1–78.0, p=0.0001) for an adverse outcome, readmission or amputation.”
The researchers, from the Diabetes Foot Clinic at Royal Infirmary, Edinburgh, concluded: “This audit shows that the higher a person’s discharge CRP, the greater the risk of that patient experiencing a subsequent adverse event (i.e. readmission, amputation or death).
“However, given that extending hospital stays is not itself without risk, clinicians must balance these risks when determining the optimum point of discharge.
“We suggest that waiting until the CRP is less than 10mg/l before discharging from hospital may represent a pragmatic balance of the risks of subsequent adverse events with the detrimental effects of extended hospital admission and excessive antibiotic use.”