Observed and expected frequency of comorbid chronic diseases in rheumatic patients.

Abstract

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