Cost-effectiveness of rapid diagnostic assays that perform directly on blood samples for the diagnosis of septic shock

Molecular diagnostic assays that test directly whole blood provide the ability to decrease inappropriate antimicrobial therapy and improve survival in patients with septic shock. We developed a decision analysis model to evaluate the cost-effectiveness of the addition of molecular assays to blood cultures in adults admitted to medical ICUs with septic shock. Under baseline assumptions, the use of molecular diagnostic methods was cost-saving in all cases that the length of hospital stay differed by 2 and 4 days between patients receiving appropriate and inappropriate antimicrobial therapy. In the case that the length of stay was the same, the use of molecular methods was cost-effective with an estimated incremental cost-effectiveness ratio (ICER) < $3000 per death averted. In the extreme that the length of stay between the 2 groups was the same, the highest cost reached was when the cost of the assay was $1000, with the estimated ICER being < $20,000 per death averted.