Cost-Effectiveness Analysis of Diagnostic Methods for Clostridium difficile Infection

OBJECTIVES: Several molecular diagnostic assays (MDA) are now commercially available for the diagnosis of Clostridium difficile infection (CDI). These assays detect genomic material associated with the pathogen’s toxin A, B and/or other genes in stool samples.  Compared with the traditional CDI laboratory assay diagnostics (e.g. enzyme immunoassay (EIA) and cytotoxin assay (CA)), MDA has a shorter turn-around time and much higher sensitivity, but requires relatively expensive instrumentation. The impact of routine use of MDA on the economics of CDI disease (via decreased frequency of testing, shorter hospitalization and less morbidity) is not clear. We evaluated if routine use of an MDA reduces the healthcare costs associated with CDI and improve outcomes --- quality-adjusted life years (QALYs) --- for CDI patients. METHODS: We performed a decision tree analysis to compare cost effectiveness of MBD with EIA and CA respectively, using data from published literature and experts’ opinions. Analyses are conducted from the societal perspective. Both incremental cost-effectiveness ratio (ICER) and net monetary benefit (NMB) are used as criteria for evaluation. RESULTS: With the base value of input variables, the ICER results show that MDA is dominant to both EIA and CA. According to the base willingness-to-pay per QALY ($150,000), the NMB of MDA vs. EIA and CA are $4,094 and $1,581, respectively. We performed one-way and probabilistic sensitivity analyses to evaluate model uncertainties. These analyses consistently demonstrate that MDA dominates EIA and CA within the predefined ranges of all input variables. CONCLUSIONS: Our study suggests that the routine use of MDA for CDI patients would result in substantial savings in US healthcare costs, compared to traditional diagnostic assays for this infection.