Inflammatory Biomarkers to Diagnose and Monitor Diabetic Foot Osteomyelitis
Condition: Diabetic Foot Ulcer
MeSH terms: Osteomyelitis; Diabetic Foot; Foot Ulcer
Study type: Observational

Summary: 
      The investigators plan to do a retrospective chart review of 500 patients admitted to the
      hospital between January 1, 2010 and December 31, 2015 with diabetic foot infections. The
      investigators will define a positive case of osteomyelitis as bone with positive bacterial
      cultures or histologic finding of acute or chronic osteomyelitis. Levels of inflammatory
      biomarkers (CRP, ESR) will be collected from the charts from the first time of diagnosis.
      Because wound healing, biomarker levels and resolution of infection are clearly affected by
      other factors such as demographics, medical/surgical history, social history, medications,
      laboratory results, peripheral arterial disease, wound severity, and treatment factors such
      as type of antibiotics, off-loading, debridement and vascular surgery interventions these
      will also be collected. The investigators will collect this clinical data for both cohorts.
    

Detailed description: 
      Introduction and Purpose:

      Foot infections are one of the most common reasons for hospitalization and amputation in
      persons with diabetes. It is often difficult to determine if diabetic foot ulcers have
      osteomyelitis. Inaccurate diagnosis of osteomyelitis leads to unnecessary antibiotic
      treatment, surgery, and amputation. In addition, there are no good diagnostic tests to
      determine when osteomyelitis has been successfully treated. The results of medical treatment
      for DFO alone are poor with success rates of 60%.

      The investigators plan a retrospective chart review of 500 patients admitted to our hospital
      between January 1, 2010 and December 31, 2015 with diabetic foot infections. We will define
      diabetic foot osteomyelitis as bone with positive bacterial cultures or histologic finding of
      acute or chronic osteomyelitis.

      The investigators also plan to review 200 foot infections in non-diabetics.

      Specific Aims Aim 1. Evaluate the effectiveness of biomarkers to diagnose diabetic foot
      osteomyelitis using bone culture and histopathology as the "gold standard" to establish the
      diagnosis.

      Aim 2. Evaluate the effectiveness of biomarkers to differentiate osteomyelitis from deep soft
      tissue infections in patients with diabetic foot ulcers.

      There is no risk to subjects, except a minimal risk of Loss of Confidentiality. Information
      gained from the analysis of data may lead to a better understanding of the mechanisms of
      diabetic ulcer formation and DFO and inform future research to develop better treatments.

      Background:

      There is a worldwide epidemic of diabetes. According to data from the World Health
      Organization, the world prevalence of diabetes among adults was 6.4% in 2010, affecting 285
      million adults worldwide. The prevalence of diabetes is expected to increase to 7.7% by 2030
      (439 million adults) [1]. In the United States, the prevalence of diabetes increased by 26%
      from 2007 to 2012, and the associated cost of managing this disease increased from $174 to
      $245 billion (41% increases) in the same time period [2]. The U.S. Centers for Disease
      Control and Prevention estimate that 26 million people in the US have diabetes [3]. By 2034
      this is expected to increase to 44 million people [4]. Diabetic foot infections are a common,
      costly, and life altering complication.

      As part of the worldwide epidemic of diabetes mellitus, the prevalence of lower extremity
      complications is rising. Patients with diabetes are now confronted with a 25% lifetime risk
      of developing a foot ulcer. Among persons with diabetes, foot infections are one of the most
      common reasons for hospitalization and lower extremity amputations. 20% of all patients with
      infected foot ulcers end up with amputation of the foot or leg; however, when there is
      osteomyelitis, the risk of amputation increases 3 fold. On average patients with diabetic
      foot osteomyelitis have longer hospitalizations (32 vs.14 days), more surgeries (65% vs.
      31%), and longer treatment with intravenous antibiotics (32 vs. 14 days) compared to patients
      with soft tissue infections.

      Diagnosing diabetic foot osteomyelitis (DFO) and monitoring resolution of infection remains a
      challenge with very little evidence that biomarkers or imaging techniques can accurately
      assess the presence of bone infection. Bone culture and histology are considered to be the
      gold standard in most guidelines to diagnose DFO but it is not routinely done in clinical
      practice. The erythrocyte sedimentation rate (ESR) has been suggested to be the best
      currently available laboratory test to diagnose and monitor DFO. Only a few small studies
      have evaluated the value of C-reactive protein (CRP) to diagnose and monitor osteomyelitis in
      the diabetic foot. Unfortunately, the level of quality of the available studies is low,
      patient populations are small and the heterogeneous use of reference tests to confirm DFO
      make it difficult to compare data.

      Preliminary Studies:

      Preliminary data suggest that CRP is a valuable marker to distinguish bone infection in
      patients with diabetic foot ulcers. Also, results show that ESR and CRP may be helpful when
      monitoring success of therapy. The investigators hypothesize that CRP will be the most
      valuable marker to diagnose diabetic foot osteomyelitis and that ESR gives the clinician more
      information during follow-up.
    

Observational model: Other
Time perspective: Retrospective
Sampling method: Non-Probability Sample
Study population: 
        Patients with foot infections.