Development and Validation of a Prognostic, Risk-Adjusted Scoring System for Operative Upper-Extremity Infections

Purpose Acute infections of the distal upper extremity (UE) can require one and possibly multiple debridements. We aimed to develop and validate a prognostic scoring system based on patient, infection, and microbiology risk factors to help with operative planning and patient counseling. Methods We studied all acute surgical UE infections distal to the elbow joint over a 5-year period. A split-sample design was created with 1:1 randomization into development and validation samples. The primary outcome was infection persistence, defined as the need for additional operative drainage according to usual indications. Multivariable logistic regression identified risk factors for persistent infections in the development sample, which was translated to a simple clinical scoring system derived from regression coefficients. The model was then tested separately against the validation sample. Results A total of 602 patients were included; 31% of all infections exhibited persistence. Independent risk factors from the development sample included diabetes (3 points), smoking (2 points), leukocytosis at presentation (2 points), animal bite mechanism (3 points), osteomyelitis (4 points), tenosynovitis (7 points), pyarthrosis (3 points), necrotizing fasciitis (11 points), and methicillin-resistant Staphylococcus aureus (3 points). These were all confirmed in the validation sample. Infections were categorized into 3 groups based on risk for persistent infection: low (less than 8 points), medium (8–11 points), and high (12 points or more). In the validation sample, the probability of persistent infection for these 3 groups was 23%, 57%, and 79%, respectively. The c statistic for the model in the validation sample was 0.79. Conclusions Persistence of acute surgical distal UE infections is mediated by patient and microbiology factors, as well as infection mechanism and type. Surgeons can use this risk-adjusted prognostic scoring system to anticipate which infections may require additional therapeutic debridement and plan operative schedules and counsel patients accordingly. Type of study/level of evidence Prognostic II.