Outcomes of osteomyelitis among patients treated with outpatient parenteral antimicrobial therapy

PURPOSE: To examine the effects of diabetes, vascular disease, age, and antimicrobial therapy on clinical outcomes, including amputation rates, in patients with osteomyelitis treated in the Outpatient setting. METHODS: We performed a retrospective chart review of patients treated with intravenous antimicrobial therapy for osteomyelitis at an outpatient infectious diseases practice. All patients were followed for at least 6 months. RESULTS: Four hundred and fifty-four patients qualified for inclusion, with follow-up information available for up to 10 years. One hundred and thirty-nine patients (31%) had recurrences and 27 (6%) had amputations. Of the recurrences, 108 (78%) occurred within 6 months and 132 (95%) within 1 year. in univariate analyses, peripheral vascular disease, diabetes, and the combination were all associated with the risk of recurrence; age (>70 years) was not. For osteomyelitis due to Staphylococcus aureus, the relative risk of recurrence, using a Cox regression model, was 0.8 for ceftriaxone (95% confidence interval [CI]: 0.4 to 1.5; P = 0.53), 1.1 for cefazolin (95% CI: 0.5 to 2.2; P = 0.80), and 2.5 for vancomycin (95% CI: 1.1 to 5.6; P = 0.04), as compared with the use of a penicillinase-resistant penicillin. CONCLUSION: Diabetes and peripheral vascular disease are important factors in determining the prognosis of patients with osteomyelitis, but age is not. Almost all recurrences of osteomyelitis occur within 1 year. Recurrence rates with osteomyelitis associated with S. aureus appear to be higher with the use of vancomycin, whereas ceftriaxone and cefazolin appear to be similar to penicillinase-resistant penicillins.