Somatic multimorbidity and self-rated health in the older population

Henrike Galenkamp, VU University Medical Center
Arjan W. Braam, Vrije Universiteit Amsterdam
Martijn Huisman, VU University; Dept. Sociology / VU Medical Center, Depts. Psychiatry & Epidemiology
Dorly J. H. Deeg, Vrije Universiteit Amsterdam

Chronic diseases are important predictors of self-rated health (SRH). Considering the high prevalence of multimorbidity in the older population, the current study investigated the relationship between multiple chronic diseases and SRH. In particular, it was investigated whether the impact is cumulative or synergistic. Age and gender were examined as potential effect modifiers. Cross-sectional data were used from 2,046 men and women, aged 57-98 years, who participated in the Longitudinal Aging Study Amsterdam (LASA). We assessed the presence of the following frequently occurring chronic diseases or disease events: chronic non-specific lung disease, cardiac disease, peripheral atherosclerosis, stroke, diabetes mellitus, arthritis, and cancer. SRH was assessed with the question ‘How is your health in general?’ and included five response categories, ranging from ‘very good’ (1) to ‘poor’ (5). Generalized ordered probit models were applied, and possible synergism was examined by testing for non-linearity of the association. When a dichotomization was made between good and less than good SRH, the association with number of diseases was rather strong, whereas it was weaker for the extreme categories of SRH (less than very good vs. very good or poor vs. very good/good/fair). The association appeared non-linear: the effect of having a single disease was larger than that of subsequent diseases. Only in the oldest group this pattern was not found. In all age groups each increment in number of diseases led to further significant decline in SRH. The findings most importantly underline the problem of multimorbidity in the older population. Second, having a single disease may increase the chance of having less than good health more than subsequent diseases. This has implications for the way the impact of specific chronic conditions is investigated.