The purpose of the study was to examine the characteristics of two self-rated health measures, generally used among older people, and the differences between them. The two measures compared were the global measure without any explicitly expressed reference point and the comparative measure where respondents are asked to compare their health with that of their age peers. First, the associations of age and functional ability with both self-rated health measures were examined. Second, the ways in which global and comparative SRH predict mortality were compared. Third, the self-rated health of older people in St. Petersburg, Russia, and Tampere, Finland, was compared. Finally, the influence of selective loss on the generality of positive health ratings in old age was examined.
The data came from the Tampere Longitudinal Study on Ageing (TamELSA), a research project on which the first structured interview was conducted in 1979. The follow-up rounds were conducted in 1989, 1999, and 2006. The St. Petersburg data for the cross-cultural study was a part of the project “Improving the Planning of Medical and Social Services within Elder care in St. Petersburg” (IPSE) in 2000. The data were collected by face-to-face interviews using structured questionnaire. The questionnaire used in the IPSE-survey was same as in TamELSA.
The study showed that the association of age with SRH was different depending on the measure used. The respondents, especially the oldest ones, tended to rate their health as better than that of their age peers. The association of age with better comparative SRH became stronger after adjustment for other health indicators. When global SRH was used the association of age with good global SRH was weaker, and vanished after adjustments. The association of functional ability was the opposite: good functional ability was associated more strongly with good global SRH than with better comparative SRH. Without adjustment global SRH predicted mortality but comparative SRH did not. After adjustment for age, comparative SRH was associated with increased mortality risk. Both SRH measures predicted mortality even at 20 years of follow-up when they were adjusted for age, sex, occupational class, chronic diseases, and functional ability.
Self-rated health was poorer among the respondents in St. Petersburg than in Tampere measured either by global or comparative SRH, and they also had more, symptoms, chronic diseases and functional disabilities than their age peers in Tampere. Differences in the factors that were associated with good self-ratings indicate there are differences in those dimensions of health and illness which are important in health ratings. The respondents in St. Petersburg rated their health as poorer even after other health indicators were adjusted for. The results indicate that the differences between the two cities are caused mainly by different ways of evaluating health: objective health status is taken into account differently in health ratings.
This study shows that health ratings in old age are influenced by the complex relationship of age, a person’s health status, and the reference group used. In global question, the respondents have more freedom when choosing their reference points whereas the explicit expression of the reference group in comparative question leads the respondents to focus more on the health of other people. The growing number of positive comparative self-ratings in old age implies that the reference group used, “health of the age peers”, is understood more and more negatively with increasing age. Comparative SRH proved to be more sensitive to age and does not measure objective health indicators similarly between age groups. It also proved to be more sensitive to selective loss. Therefore, in studies where the age range is wide, and also in clinical settings, the global measure should be preferred. Cultural differences indicate that health comparisons between different cultures should not be made on the basis of health ratings only.
