Evaluating the utility of inflammatory markers in the diagnosis of soft tissue abscesses of the forearm and hand.

Upper extremity abscesses frequently present to the acute care setting with inconclusive physical examination and imaging findings. We sought to investigate the diagnostic accuracy of inflammatory markers including white blood cell (WBC) count, erythrocyte sedimentation rate (ESR), and C-reactive protein (CRP). A retrospective cohort study was performed to identify subjects $\ge 18$  years treated with surgical debridement of upper extremity abscesses at our institution between January 2012 and December 2015. In this study, 188 patients were screened, and 72 met the inclusion criteria. A confirmed abscess as defined by culture positivity was present in 67 (93.1 %) cases. The sensitivity of WBC, ESR, or CRP individually was 0.45, 0.71, and 0.81. The specificity of WBC, ESR, or CRP individually was 0.80, 0.80, and 0.40. In combination all three markers when positive had a sensitivity of 0.26 and specificity of 1.0. These values were similar among patients with diabetes and those with obesity. With the highest sensitivity and lowest specificity, CRP exhibited the most utility as a screening test (level IV).