DOI: 10.5061/dryad.jm63xsj7r
title: Discordant Clostridioides difficile diagnostic assay and treatment practice: a cross-sectional study in a tertiary care hospital, Geneva, Switzerland

description: Objectives: To determine the proportion of patients who received a
 treatment for Clostridioides difficile infection (CDI) among those
 presenting a discordant Clostridioides difficile diagnostic assay and to
 identify patient characteristics associated with the decision to treat
 CDI. Design: Cross-sectional study. Setting: Monocentric study in a
 tertiary care hospital, Geneva, Switzerland Participants: Among 4562 adult
 patients tested for C. difficile between March 2017 and March 2019, 208
 patients with discordant tests’ results (positive nucleic acid
 amplification test [NAAT+]/negative enzyme immunoassay [EIA-]) were
 included. Main outcome measures: Treatment for CDI. Results: CDI treatment
 was administered in 147 (71%) cases. In multivariate analysis, an
 abdominal computed tomography scan with signs of colitis (OR 14.7; 95% CI
 1.96-110.8) was the only factor associated with CDI treatment.
 Conclusions: The proportion of NAAT+/EIA- patients who received treatment
 questions the contribution of the EIA for the detection of toxin A/B after
 NAAT to limit overtreatment. Additional studies are needed to investigate
 if other factors are associated with the decision to treat.
description: We
 conducted a cross-sectional
 study at Geneva University
 Hospitals, a 2000-bed Swiss tertiary care centre. Clinical and biological
 data (results of NAAT/EIA assays performed on stool samples) were
 collected from electronic medical records (EMR) and the hospital
 bacteriology laboratory, respectively. Inclusion criteria were all adult
 patients (≥18 years) hospitalised or not, with
 <i>C. difficile</i> toxin assays performed on stool samples between 1 March 2017 and 1 March 2019 that yielded discordant results (NAAT+/EIA-). Exclusion criteria were asymptomatic patients (without diarrhoea, ileus or toxic megacolon), paediatric patients, patients with a treatment against <i>C. difficile</i> introduced ≥ 48 h before the results of tests, or without clinical data available in EMR form. In patients presenting several tests with discordant results over the study period, only the first test was considered for analysis. The study was approved by the Geneva cantonal ethics commission and a waiver of informed consent was granted due to its retrospective nature
description: The decision was made to
 include all eligible patients and no formal sample size calculation was
 performed. Instead, we restricted the number of investigated parameters
 before any confirmatory analysis. Based on the “10 events per variable”
 rule of thumb, we limited the number of parameters investigated to
 eight
 factors selected among known risk
 factors and clinical characteristics compatible with CDI. Patient
 characteristics and CDI risk factors were described overall and
 by treatment for
 CDI and reported as
 frequencies and percentages. A multivariate logistic regression model
 using a backward stepwise method was performed to determine which
 parameters were independently associated with CDI
 treatment. At each step, starting
 from all eight
 parameters, the variable with the
 highest p-value on the likelihood ratio test was removed from the model
 until all remaining factors were statistically significantly associated
 with CDI
 treatment at a two-sided level of
 5%. Sensitivity analyses were
 performed to assess the robustness of the results when deceased patients
 were a) excluded from the analysis and b) considered as not
 treated. Missing data were
 systematically removed from analyses. Statistical significance
 was assessed at a two-sided 0.05 level for all
 analyses. All statistical analyses
 were performed using Stata software, version 15 (StataCorp, College
 Station, TX).