Revisiting the effect of referral bias on the clinical spectrum of infective endocarditis in adults

Z. A. Kanafani, S. S. Kanj, C. H. Cabell, E. Cecchi, A. De Oliveira Ramos, T. Lejko-Zupanc, P. A. Pappas, H. Giamerellou, D. Gordon, C. Michelet, P. Muñoz, O. Pachirat, G. Peterson, R. S. Tan, P. Tattevin, V. Thomas, A. Wang, F. Wiesbauer, D. J. Sexton

Research output: Contribution to journalArticlepeer-review

45 Scopus citations


Referral bias occurs because of the clustering of patients at tertiary care centers. This may result in the distortion of observed clinical manifestations of rare diseases. This analysis evaluates the effect of referral bias on the epidemiology of infective endocarditis (IE) in the International Collaboration on Endocarditis-Prospective Cohort Study (ICE-PCS). This is a prospective multicenter cohort study comparing transferred and non-transferred patients with IE. Factors independently associated with transfer status were evaluated using multivariable logistic regression. A total of 2,760 patients were included in the analysis, of which 1,164 (42.2%) were transferred from other medical centers. Transferred patients more often underwent surgery for IE (odds ratio [OR]∈=∈2.5; 95% confidence interval [CI] 1.9-3.2). They were also more likely to have complications such as stroke (OR∈=∈1.5; 95% CI 1.3-1.9), heart failure (OR∈=∈1.4; 95% CI 1.1-1.6), and new valvular regurgitation (OR∈=∈1.3; 95% CI 1.1-1.6). The in-hospital mortality rates were similar in both groups. Patients with IE who require surgery and suffer complications are referred to tertiary hospitals more frequently than patients with an uncomplicated course. Hospital transfer has no obvious effect on the in-hospital mortality. Referral bias should be taken into consideration when describing the clinical spectrum of IE.

Original languageEnglish (US)
Pages (from-to)1203-1210
Number of pages8
JournalEuropean Journal of Clinical Microbiology and Infectious Diseases
Issue number10
StatePublished - Oct 2010

ASJC Scopus subject areas

  • Microbiology (medical)
  • Infectious Diseases


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