Empirical treatment of bacteraemic urinary tract infection - Evaluation ofa decision support system

Introduction: In a Danish county with a low prevalence of antibiotic resist ance to most antibiotics, we have constructed and evaluated a decision supp ort system (DSS) for guidance of empirical antibiotic therapy in patients w ith bacteraemia originating from the urinary tract. Methodology: The DSS was based upon a causal probabilistic network, and a d ecision theoretic approach was used to balance the costs of antibiotic ther apy against the therapeutic benefit. The costs included direct cost of purc hasing antibiotics, side effects, and the risk of development of antibiotic resistance. The therapeutic benefit was defined as the increase in life-ex pectancy caused by antibiotic therapy. Life-years were chosen as the common currency unit. Four hundred and ninety-one bacteraemias seen during 1992-1 994 were used to construct the DSS (derivation set), and 426 bacteraemias d uring 1995-1996 were used for evaluation (validation set). The cases were i dentified in a regional register of bacteraemias. The study was non-interve ntional. Results: The DSS suggested antibiotics which would provide coverage in 377 of the 426 episodes (88.5%) compared to 259 episodes (60.8%) for which empi rical therapy actually provided coverage (p<0.01, McNemar-test). The regime ns suggested by the DSS included mecillinam as monotherapy in 240 episodes (56.3%), gentamicin as monotherapy in 81 (19.0%), and a combination of gent amicin and ampicillin in 80 (18.8%). Conclusion: A decision theoretic approach shows promise of improving empiri cal antibiotic treatment, and may be a measure to support an antibiotic pol icy.