318 - Deferring Amputation in Diabetic Foot Osteomyelitis: Doing more Harm than Good?

Background: Diabetic foot osteomyelitis (DFO) is a leading cause of below knee amputation (BKA). Even when medical treatment is deemed unlikely to succeed, patients with DFO are often resistant to amputation.

Methods: An observational cohort analysis was done on patients with DFO at Michigan Medicine who were evaluated by podiatry and recommended BKA from Oct 2015 - Jun 2019. Primary outcome was mortality after BKA recommendation. Secondary outcomes were healing of affected limb, rate of BKA or above knee amputation (AKA) and total antibiotic days in the 6 months following. All intravenous antibiotics and oral courses of linezolid and fluoroquinolones were captured.

Results: Of 44 patients with DFO, 18 chose BKA, 26 chose medical management with wound care. Mean age of the cohort was 61, 68% male, 80% white with a median Charlson Comorbidity Index of 6 (IQR 4,7). The two groups were similar with regards to demographics and comorbid conditions. Those who chose medical management did so because their infection was non-life-threatening and they desired to avoid amputation.
One-year mortality was greater in patients who were medically managed compared to those who had BKA (23.1% vs 0%, OR 11.7, 95% CI 0.6-222.9). Considering only the 33 patients who were followed for at least 2 years, 2-year mortality was also greater in the medically managed group compared to the BKA group (38.5% vs 5.6%, OR 10.6, 95% CI 1.2-92.7, Figure 1). Fewer patients in the medical management group had complete healing of their wound/stump compared to the BKA group (46.2% vs 88.9%, OR 9.3, 95% CI 1.8-49.1). In the medically managed group, 18 (69%) patients went on to require BKA or AKA at a median of 76.5 days compared to 2 (11%) in the BKA group who required AKA at 1 and 11 days following recommendation. Median antibiotic days were significantly greater in the medically managed group compared to the BKA group (55 IQR 42,78 vs 17 IQR 10,37, p=0.0017).Figure 1


Conclusion: In this cohort of DFO patients where BKA was recommended, medical management was associated with increased mortality, poor healing of the affected limb, and excess antibiotic exposure compared to BKA. These findings are particularly notable as case mix and severity of illness were similar between the two groups. This study can be used to inform providers and patients in cases where BKA is recommended.