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Observed and expected frequency of comorbid chronic diseases in rheumatic patients
  1. E Loza1,
  2. J A Jover1,
  3. L Rodriguez-Rodriguez1,
  4. L Carmona2,
  5. and the EPISER Study Group
  1. 1
    Rheumatology Unit, Hospital Clínico San Carlos, Madrid, Spain
  2. 2
    Research Unit, Fundación Española de Reumatología, Madrid, Spain
  1. Loreto Carmona, Research Unit, Fundación Española de Reumatología, Calle Marques del Duero, 5, 1a, 28001 Madrid, Spain; lcarmona{at}


Objective: To estimate and compare the observed and expected prevalence of the co-existence of rheumatic diseases (RD) with other chronic conditions.

Methods: The self-reported diagnosis of chronic conditions was obtained from the 2192 participants in a national health survey (Spain, 1999–2000) We compared the estimated prevalence of the co-existence of a RD with other chronic conditions, to the expected prevalence using two-sample test of proportion.

Results: The observed (O) prevalence was significantly higher than expected (E) in the following combination of self-reported diseases: RD+arterial hypertension (O/E ratio = 1.88), RD+diabetes mellitus (O/E ratio = 2.07), RD+hypercholesterolemia (O/E ratio = 1.87), RD+cardiological (O/E ratio = 1.83), and RD+digestive diseases (O/E ratio = 2.07). The prevalence of selected co-existent pairs of diseases is more frequent with increasing age and differs between women and men.

Conclusions: The excess in prevalence of some combinations of diseases may serve as a reminder to the rheumatologists that many of their patients will have co-existent disease of which they need to be aware to properly plan their management. It may also be a sign of common risk factors between diseases or of adverse events.

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  • A list of the full EPISER Study Group appears in the Appendix.

  • Funding: EPISER was supported by a grant from the Fondo de Investigaciones de la Seguridad Social (FIS 99/0251), and sponsored by Merck Sharp and Dohme España.

  • Competing interests: None declared.