[Estimation of costs attributable to nosocomial infection: prolongation of hospitalization and calculation of alternative costs].

BACKGROUND: Nosocomial infection represents a prolongation of hospital stay and an increase of costs. The aim of the study was to estimate attributable costs by means of two methods: calculation of costs resulting from an increase of hospital stay and calculation of costs attributed to services.
METHODS: A matched case-control study was carried out with a cohort population. An appropriate control was found for 63 patients with surgical site infection, for 30 patients with respiratory infection and for 55 with urinary infection. The estimation of costs attributable to services includes the case-control pairs with surgical site infection and was performed of the sum of costs of diagnostic and therapeutic services rendered in the care of the surgical site infection.
RESULTS: The median of postoperative stay was 21 days for cases with surgical site infection vs 10 days for controls (p < 0.001); the median length of stay was 21.5 days for cases with respiratory infection vs 11.5 days for controls (p < 0.01); and for urinary infection the median length of stay was 21 days for cases vs 15 days for controls (p < 0.01). The surgical site infection cost attributed to extra days was 310,310 pesetas and the surgical site infection cost attributed to service cost was 220,546 pesetas.
CONCLUSIONS: Nosocomial infection produces a increase median hospital stay of 7-10 days. In absence of a precise accounting system, the prolongation of hospital stay was considered as the more objective date to estimate the costs.