The effect of Clostridium difficile infection on cardiac surgery outcomes

Clostridium difficile (CD) is a common cause of healthcare-associated infectious colitis that complicates about 1% of all hospital stays in the U.S. The impact of CD on outcomes after coronary artery bypass grafting (CABG) and valvular surgery (VS) is not well known.

The Nationwide Inpatient Sample (2002-2009) was queried to identify CABG and VS patients utilizing International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) diagnosis codes. Rates of CD, post-operative endocarditis and mediastinitis, hospital mortality rate, and resource utilization were evaluated.

We identified 421,294 and 90,923 patients of age 40 yrs and older who underwent CABG and VS, respectively. The CD infection was more likely to develop in patients undergoing VS than in those having CABG (odds ratio [OR] 1.8; 95% confidence interval [CI] 1.64-1.92) and was more likely after urgent or emergency admission than after elective admission (OR 1.8; 95% CI 1.68-1.94). There was a greater likelihood of mediastinitis in patients with CD after CABG than in non-complicated cases without CD, both by univariable (OR 6.0; 95% CI 3.07-11.62) and multivariable analysis with adjustment for patient age, gender, race, type of admission, and co-morbidities (OR 3.1; 95% CI 1.49-6.51). The infection thus was most likely a result of the antibiotics used to treat mediastinitis, as the patients treated for mediastinitis were most likely to develop CD. There was a significant association in patients with CD and endocarditis who underwent VS but not in patients who did not have CD. The CD infection in these patients thus was most likely a result of the antibiotics used to treat endocarditis. Endocarditis and CD developed 3.2 times (95% CI 2.65-3.97) as often as in patients without CD, a finding that was confirmed by multivariable analysis (OR 2.2; 95% CI 1.70-2.84). At the same time, in patients having VS, there was no significant association of CD and mediastinitis. Clostridium difficile infection affected the hospital mortality rate significantly after both CABG (OR 2.0; 95% CI 1.65-2.35) and VS (OR 1.9; 95% CI 1.51-2.39). Development of CD increased median hospital length of stay and cost dramatically after both CABG (from 7 d to 19 d and from $33,105 to $65,535, respectively; p<0.0001 for both) and VS (from 8 d to 24 d and from $41,876 to $95,699, respectively; p<0.0001 for both).

The development of CD worsened significantly the outcomes of adult patients undergoing cardiac surgery. There was a greater risk of CD in patients with either mediastinitis or endocarditis. The infection was associated with a higher hospital mortality rate, longer hospital stays, and greater cost after both CABG and VS.