Between April 1999 and April 2011, 41,466 patients underwent cardiac surgery at our center. Demographics and pre-, intra-, and post-operative data were collected prospectively for all patients in a digital hospital registry. A review of this registry revealed that 1256 out of 41,466 (3.0%) patients were diagnosed with a CDI during their hospital stay. The presence of a CDI was verified using medical records, discharge summaries from other institutions, and documentation of findings from other departments. The local ethics committee approved the study (University of Leipzig, Az.: 212–15-01062015). The study design, anonymous data acquisition, and the publication of the data were in accordance with the Declaration of Helsinki.
Diagnosis of CDI
CDI was diagnosed by a combination of clinical symptoms and laboratory testing. The criteria for a CDI were frequent stool (> 3 times/day) with unformed consistency (water content of the stool > 75%), increased stool masses (> 250 g/day), and stool testing positive for CD. The stool examination was made with cytotoxicity assay and/or enzyme immunoassay for CD toxins. All patients who fulfilled these criteria were included in this retrospective cohort study (n = 1256). Patients were excluded if they met any of the following criteria: age < 18 years, a hospital stay of less than 48 h, and positive test for CD at the time of hospital admission. The occurrence of gastrointestinal complications (e.g. pseudomembranous colitis, toxic megacolon, gastrointestinal bleeding, ileus, ischemia, or perforation, etc.) and/or the need for a laparotomy after cardiac surgery were defined as criteria for a fulminant CDI (Table 1).
Unless otherwise indicated, categorical variables are presented as numbers and percentage, and continuous parameters are expressed as mean ± standard deviation (SD). Fisher's exact test or a Chi-squared test was used to assess differences for categorical variables, and Student's t-test or a Wilcoxon rank-sum test was applied for continuous parameters. Overall survival rates were analyzed using the Kaplan-Meier method. Statistical differences were calculated by the log-rank test. Multivariate analysis was performed using a binary logistic regression model (stepwise backward) to differentiate independent risk factors for developing a fulminant course of CDI. Variables used in the equation were prior cardiac surgery, pre-operative dialysis, pre-operative ventilation, pre-operative low cardiac output, emergency surgery, minimally invasive surgery, diabetes mellitus type 2, age > 80 years, left ventricular ejection fraction (LVEF) < 30%, New York Heart Association (NYHA) class ≥III, length of surgery > 200 min, cross-clamp time > 130 min, > 8 units of red blood cell (RBC) concentrates, > 5 units of fresh-frozen plasma (FFP).
All tests were two-sided, with a significance level alpha = 0.05. Unless otherwise stated the analyses were performed by IBM SPSS Statistics for Macintosh, Version 24.0 (IBM Corp., Armonk, NY, USA). All authors had full access to datasets and upheld their integrity. They read and agreed to the manuscript as written.
BMC Anesthesiol. 2018;18(133) © 2018 BioMed Central, Ltd.