A hospital-level cost-effectiveness analysis model for toxigenic Clostridium difficile detection algorithms

Prevalence of and factors associated with inappropriate Clostridioides difficile testing in a teaching hospital in Korea

Background

Given the increasing incidence of Clostridioides difficile infections in Korea, there has been an increase in inappropriate testing for C. difficile, which has rendered overdiagnosis of asymptomatic colonisers common. We aimed to investigate the appropriateness of C. difficile testing and the related factors.

Methods

We retrospectively reviewed the medical records of patients who were admitted to a 1300-bed tertiary-care teaching hospital in Korea and were tested for C. difficile infection from September 2019 to November 2019. We performed logistic regression analysis to investigate factors related to inappropriate testing. Further, a survey was conducted on physicians to assess the knowledge and ordering patterns of C. difficile testing.

Results

We included 715 tests from 520 patients in the analysis. Testing was classified as hospital-onset and community-onset and subclassified as appropriate and inappropriate following an algorithmic method. Among the 715 tests, 576 (80.6%) and 139 (19.6%) tests were classified as hospital-onset and community-onset, respectively. Among the hospital-onset tests, 297 (52%) were considered inappropriate. The risk of inappropriate testing increased when C. difficile tests were conducted in the emergency room (OR 24.96; 95% CI 3.12–199.98) but decreased in intensive care units (OR 0.36, 95% CI 0.19–0.67). The survey was conducted on 61 physicians. Internal medicine physicians had significantly higher scores than non-internal medicine physicians (7.1 vs. 5.7, p = 0.001). The most frequently ordered combination of tests was toxin + glutamate dehydrogenase (47.5%), which was consistent with the ordered tests.

Conclusion

Almost half of the C. difficile tests were performed inappropriately. The patient being located in the emergency room and intensive care unit increased and decreased the risk of inappropriate testing, respectively. In a questionnaire survey, we showed that internal medicine physicians were more knowledgeable about C. difficile testing than non-internal medicine physicians. There is a need to implement the diagnostic stewardship for C. difficile, especially through educational interventions for emergency room and non-internal medicine physicians.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13756-022-01111-0.

A cost of illness comparison for toxigenic Clostridioides difficile diagnosis algorithms in developing countries

BACKGROUND

Availability of several commercial tests with different Clostridioides difficile targets contributes to uncertainty and controversies around the optimal diagnostic algorithm. While numerous studies have estimated the financial impact of C. difficile infection, models to guide testing strategies decisions in developing countries, where economic value significantly impacts clinical practice, are currently not available.

AIM

To determine the cost of illness of different C. difficile infection (CDI) diagnostic strategies in developing countries.

METHODS

Cost-comparison analysis was performed to compare eleven different algorithms of CDI diagnosis. The basis of calculation was a hypothetical cohort of 1000 adult inpatients suspected of CDI. We analyzed turnaround time of test results (i.e., time from taking sample to results emission), test performance (i.e., sensitivity and specificity) and testing costs. Patients were divided in true positive, false positive, true negative and false negative in order to integrate test performance and economics effects. Additional medical costs were calculated: costs of hygiene, medication, length of stay and intensive care unit costs, based on a Brazilian University Hospital costs. CDI prevalence was considered 22.64%.

FINDINGS

From laboratory-assisted tests, simultaneous glutamate dehydrogenase (GDH) and toxin A/B rapid immunoassay arbitrated by nucleic acid amplification test (NAAT) presented the lowest cost of illness (450,038.70 USD), whereas standalone NAAT had the highest (523,709.55 USD). Empirical diagnosis only presented the highest overall cost (809,605.44 USD).

CONCLUSION

The two-step algorithm with simultaneous GDH and toxin A/B rapid immunoassay arbitrated by NAAT seems to be the best strategy for CDI diagnosis in developing countries.

Cost-Effectiveness Analysis of Four Common Diagnostic Methods for Clostridioides difficile Infection

BACKGROUND

No studies have evaluated the cost-effectiveness of single and two-step different diagnostic test strategies for Clostridioides difficile infection (CDI), including direct and indirect costs.

OBJECTIVE

To evaluate the cost-effectiveness of commonly available diagnostic tests for CDI including nucleic acid amplification testing (NAAT) alone, glutamate dehydrogenase followed by enzyme immunoassay for toxin (GDH/EIA), GDH then NAAT (GDH/NAAT), and NAAT then EIA (NAAT/EIA).

DESIGN

Decision tree model from the US societal perspective with inputs derived from the literature. Willingness-to-pay threshold was set at $150,000 per quality-adjusted life year (QALY) gained. To assess the impact of uncertainty in model inputs on the findings, we performed one-way and probabilistic sensitivity analyses.

PARTICIPANTS

We conducted the analysis to represent a population aged 65 years old with diarrhea who received a CDI diagnostic test.

MAIN MEASURES

Incremental cost-effectiveness ratios (ICER) and incremental net monetary benefits (INMB).

KEY RESULTS

NAAT alone was the most cost-effective approach overall; GDH/NAAT was the most cost-effective two-step option. NAAT alone led to the highest QALYs gained, at an incremental cost of $54,547 (vs. GDH/NAAT), $55,410 (vs. GDH/EIA), and $50,231 (vs. NAAT/EIA) per QALY gained. NAAT/EIA was not cost-effective compared to any other strategy. GDH/NAAT resulted in a higher QALY compared to GDH/EIA, at an incremental cost of $96,841 per QALY gained. Variability in the likelihood of comorbidities, CDI probability, and age at disease onset did not substantially change the results. One-way sensitivity analyses showed that results were most sensitive to likelihood of recurrence, followed by CDI mortality rate and probability of severe CDI. Probabilistic sensitivity analyses explored known uncertainties in the base case and confirmed the robustness of the results.

CONCLUSIONS

NAAT alone and GDH/NAAT (among the two-step options) were the most cost-effective diagnostic test approaches for CDI.

Laboratory Tests for the Diagnosis of Clostridium difficile

Clostridium (reclassified as " Clostridioides ") difficile is an anaerobic, gram-positive bacterium that causes significant disease through elaboration of two potent toxins in patients whose normal gut microbiota has been altered through antimicrobial or chemotherapeutic agents (dysbiosis). The optimum method of laboratory diagnosis is still somewhat controversial. Recent practice guidelines published by professional societies recommend a two-step approach beginning with a test for glutamate dehydrogenase (GDH), followed by a toxin test and/or a nucleic acid test. Alternatively, in institutions where established clinical algorithms guide testing, a nucleic acid test alone is acceptable. Nucleic acid tests are the methods of choice in approximately 50% of laboratories in the United States. These tests are considered as the most sensitive methods for detection of C. difficile in stool and are the least specific. Because of the lower specificity with nucleic acid tests, some clinicians believe that toxin enzyme immunoassays are better predictors of disease, despite their known poor performance in certain patient populations. This review will discuss the advantages and disadvantages of the currently available test methods for the diagnosis of C. difficile with a brief mention of some novel assays that are currently in clinical trials.

Performance evaluation of the Verigene®Clostridium difficile nucleic acid test, an automated multiplex molecular testing system for detection of C. difficile toxin

The Verigene^®Clostridium difficile nucleic acid test (Verigene^® CDF test) is an automatic and rapid detection system for the genes encoding tcdA, tcdB, binary toxin, and the single nucleotide deletion at base pair 117 in the tcdC based on microarray and PCR amplification. We compared the performance of the Verigene^® CDF test to that of two enzyme immunoassays, C. DIFF QUIK CHEK COMPLETE and X/Pect Toxin A/B, using 118 specimens. We found overall concordance rates of 81.4% and 78.8% between C. DIFF QUIK CHEK COMPLETE and Verigene^® CDF test, and X/Pect Toxin A/B and Verigene^® CDF test. The Verigene^® CDF test showed the highest sensitivity (93.9%) and had a specificity of 96.5%. The sensitivity and specificity were respectively 45.5 and 94.1% for C. DIFF QUIK CHEK COMPLETE and 27.3 and 100.0% for X/Pect Toxin A/B. These results indicated that the Verigene^® CDF test was highly accurate for the detection of C. difficile toxin in fecal specimens and supported its use in daily diagnostic practice.