Clinical study
Influence of referral bias on the apparent clinical spectrum of infective endocarditis☆

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Abstract

purpose: To assess the effect of referral bias on the clinical spectrum of infective endocarditis.

patients and methods: We performed a retrospective study comparing a population-based cohort of incidence cases from Olmsted County, Minnesota, with a cohort of referred cases from the practice of the Mayo Clinic during the period from 1970 to 1987.

results: In the community cohort, age was an important risk factor for acquiring endocarditis (incidence rate ratio 8.8:1 for age 65 years or older versus age less than 65 years), but episodes in elderly patients were underrepresented in the referral practice. The proportion of cases due to Staphylococcus aureus was greater in the community than in the referral practice (p <0.02), while a trend toward overrepresentation of enterococcal endocarditis was seen in the referral population (p = 0.057). Symptom duration prior to diagnosis was significantly shorter in the community. Overall, measures of in-hospital morbidity and mortality were similar in the two populations, but advanced age was associated with adverse outcome in the community cohort.

conclusion: The clinical spectrum of infective endocarditis may be distorted by referral. The increased risk of endocarditis in the elderly underscores the importance of adherence to recommendations for prophylaxis in this patient population.

References (22)

  • AJ Hickey et al.

    Mitral valve prolapse and bacterial endocarditis: when is antibiotic prophylaxis necessary?

    Am Heart J

    (1985)
  • RO Brandenburg et al.

    Infective endocarditis—a 25 year overview of diagnosis and therapy

    J Am Coil Cardiol

    (1983)
  • MR Griffin et al.

    Infective endocarditis, Olmsted County, Minnesota, 1950 through 1981

    JAMA

    (1985)
  • AW Karchmer

    Antibiotic therapy of nonenterococcal streptococcal and staphylococcal endocarditis: current regimens and some future considerations

    J Antimicrob Chemother

    (1988)
  • D Kaye et al.

    Bacterial endocarditis: the changing pattern since the introduction of penicillin therapy

    Antimicrob Agents Chemother

    (1961)
  • LT Kurland et al.

    Mayo Clinic records linkage system in the Rochester-Olmsted Epidemiology Program Project

  • LT Kurland et al.

    Population studies in Rochester and Olmsted County, Minnesota, 1900–1968

  • CF Von Reyn et al.

    Infective endocarditis: an analysis based on strict case definitions

    Ann Intern Med

    (1981)
  • DJ Schroeder et al.

    A SAS Macro which utilizes local and reference population counts appropriate for incidence, prevalence, and mortality rate calculations in Rochester and Olmsted County, Minnesota

  • EJ Bergstralh et al.

    Projected Rochester and Olmsted County populations for 1981–1995

    Technical Report Series no. 38

    (February 1988)
  • BS Schoenberg

    Calculating confidence intervals for rates and ratios: simplified method utilizing tabular values based on the Poisson distribution

    Neuroepidemiology

    (1983)

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    ☆

    This study was supported in part by Research Grants AR-30582 and HL-24325 from the National Institutes of Health, United States Public Health Service

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