Evaluation of fixed and variable hospital costs due to Clostridium difficile infection: institutional incentives and directions for future research.

Background: Economic analysis of Clostridium difficile infection (CDI) should consider the incentives facing institutional decision-makers. To avoid overstating the financial benefits of infection prevention, fixed and variable costs should be distinguished.

Aim: To quantify CDI fixed and variable costs in a tertiary referral hospital during August 2015.

Methods: A micro-costing analysis estimated CDI costs per patient, including the additional costs of a CDI outbreak. Resource use was quantified after review of patient charts, pharmacy data, administrative resource input, and records of salary and cleaning/decontamination expenditure.

Findings: The incremental cost of CDI was €75,680 (mean: €5,820 per patient) with key cost drivers being cleaning, pharmaceuticals, and length of stay (LOS). Additional LOS ranged from 1.75 to 22.55 days. For seven patients involved in a CDI outbreak, excluding the value of the 58 lost bed-days (€34,585); costs were 30% higher (€7,589 per patient). Therefore, total spending on CDI was €88,062 (mean: €6,773 across all patients). Potential savings from variable costs were €1,026 (17%) or €1,768 (26%) if outbreak costs were included. Investment in an antimicrobial pharmacist would require 47 CDI cases to be prevented annually. Prevention of 5%, 10% and 20% CDI would reduce attributable costs by €4,403, €8,806 and €17,612. Increasing the incremental LOS attributable to CDI to seven days per patient would have increased costs to €7,478 or €8,431 (if outbreak costs were included).

Conclusion: As much CDI costs are fixed, potential savings from infection prevention are limited. Future analysis must consider more effectively this distinction and its impact on institutional decision-making.