Effects of local antibiotics in calcium-sulphate granules for the treatment of diabetic forefoot osteomyelitis: a propensity-matched observational study

Background To assess the effects of a local antibiotic delivery system on the incidence of post-surgical infective complications after surgical procedures in patients with diabetic foot osteomyelitis (DFO). Methods A retrospective study was carried out on patients with forefoot DFO associated with soft tissue infection undergoing minor amputations using local antibiotics in calcium-sulphate granules. Patients were matched with a historical series using propensity-score matching. The principal endpoint was a composite of relapse/recurrence/new onset of DFO, infection/ dehiscence at the surgical site, re-intervention for abscesses drainage, and major amputation. Direct costs were analysed as a secondary endpoint. Results Composite endpoint occurred in 19% and 36.4% (p=0.17) of cases and controls, respectively. Only three patients in the control group had recurrent DFO. After adjusting for ulcer duration, the risk of infective complications and major amputation was significantly lower (Hazard Ratio [HR] 0.20 [0.04;0.95], p=0.047) and the 90-day healing rate was significantly higher (HR 4.44 [1.03;19.07], p=0.045) in cases than in controls. The median direct healthcare costs for cases and controls during the 90-day follow-up were €2,050 [1,829;3,946] and €1,731 [1,028;14,817] per patient, respectively (p=0.072). Median costs for antibiotics were lower for cases than controls (p<0.001).