Background: Hospital-acquired bloodstream infections (BSIs) are relatively rare but do not occur randomly. This suggests that unobserved confounding factors can bias estimates of BSI-associated incremental costs of care. Compared with previous studies, this analysis used a large sample size for greater precision, actual cost-accounting data, and case matching combined with bounding estimates to correct for bias.
Methods: Data from 1,355,647 admissions during 69 months in 55 hospitals were collected from a large population database. BSIs were identified by the Nosocomial Infection Marker, a well-validated, electronic, laboratory-based marker used for automatic infection surveillance. Costs were obtained by matching laboratory data with hospital accounting system calculations and converted to 2006 US dollars.
Results: Of 58,376 presumed nosocomial infections, 12,578 (21.6%) were identified as BSIs. More than 50% of BSIs occurred within the first week of hospitalization and 80% during the first 2 weeks. Various analyses resulted in the following estimates of BSI-associated incremental costs: basic regression analysis, $19,643 (P < .0001; 95% confidence interval [CI]: $9026-$30,260); excluding infections occurring after day 14, $19,427 (P < .001; 95% CI: $8867-$29,986); excluding infections occurring after day 7, $20,600 (P < .001; 95% CI: $10,123-$30,077); controlling for other nosocomial infections, $12,774 (P < .001; 95% CI: $6257-$19,290); and controlling for length of stay, $5534 (P < .012; 95% CI: $1282-$9785).
Conclusion: Even when intentionally underestimated, BSI-associated increased costs are substantial. True costs of BSIs are likely to be between $10,000 and $20,000. More research is needed to explore how controlling BSI costs may affect the cost of inpatient care.