Self-rated health and mortality in a prospective Chinese elderly cohort study in Hong Kong

Highlights

• Worse age-comparative self-rated health (SRH) predicted higher mortality in Hong Kong.

• Worse self-comparative SRH did not predict higher mortality.

• The association of age-comparative SRH with death was weaker than that in the West.

• Assessments of health and cause-composition of death may be contextually specific.

• The association of SRH with death did not vary with socioeconomic position.

Abstract

Objectives

In the West, self-rated health reliably predicts death, but conceptualizations of health and cause-composition of mortality may be contextually specific. Little is known as to how self-rated health predicts death in non-Western settings.

Methods

Multivariable Cox regression analysis was used to assess the adjusted associations of age-comparative and self-comparative self-rated health with death from all- and specific-causes using a population-based cohort of 66,820 Chinese (65 + years) enrolled from 1998 to 2001 at 18 Elderly Health Centers in Hong Kong, and followed until May 31, 2012.

Results

During an average of 10.9 years follow-up, 19,845 deaths occurred with 6336 from cancer. Worse age-comparative self-rated health, compared with better, was positively associated with death from all-causes (hazard ratio 1.68, 95% confidence interval 1.59, 1.77), cardiovascular disease (hazard ratio 1.83, 95% confidence interval 1.66, 2.02), stroke (hazard ratio 1.93, 95% confidence interval 1.63, 2.29), ischemic heart disease (hazard ratio 1.77, 95% confidence interval 1.51, 2.08), cancer (hazard ratio 1.17, 95% confidence interval 1.06, 1.30) and respiratory disease (hazard ratio 2.25, 95% confidence interval 2.01, 2.52), adjusted for age and sex. Self-comparative self-rated health was not associated with higher mortality.

Conclusion

Age-comparative self-rated health predicted death in older people from a non-Western setting although the association was less marked than in Western settings.

Introduction

Self-rated health (SRH), a subjective assessment of health status, is a powerful predictor of mortality in older persons. SRH is as an important health indicator which is easy to measure and provides a good reflection of health status (de Bruin et al., 1996). SRH may be assessed as global SRH using questions such as “What do you think of your health in general?” (Eriksson et al., 2001, Idler and Benyamini, 1997) or as comparative SRH, including age-comparative SRH (comparing oneself to other people of the same age) and self-comparative SRH (comparing oneself to one's own status a year earlier) (Alfonso et al., 2012, Fernández-Ruiz et al., 2013). In the West, measurement methods for SRH such as type of scale, wording of the question and number of options differ; both global and age-comparative SRH predict death (Fernández-Ruiz et al., 2013, Lima-Costa et al., 2012, Young et al., 2010) although comparisons are not always consistent. Sargent-Cox et al. (2010) reported that global SRH was a better predictor of all-cause mortality than age-comparative SRH while Fernández-Ruiz et al. (2013) reported that age-comparative SRH was better. However, self-comparative SRH is a weaker predictor of mortality (Bath, 2003, Fernández-Ruiz et al., 2013). The magnitude of association of SRH with mortality may vary by cause of death. SRH might be more strongly associated with diseases with a prolonged course and substantial impact on daily life, such as cardiovascular and respiratory diseases, than diseases without notable signs in the early stages which then develop rapidly such as cancer (Fernández-Ruiz et al., 2013). SRH is easy to measure, and could be a health indicator for older people given it might reveal health status before symptoms develop.

Most studies of the association of SRH with mortality relate to Western populations, where associations may vary by socioeconomic position (Burström and Fredlund, 2001, Huisman et al., 2007, Møller et al., 1996, Mossey and Shapiro, 1982). However, these observations may not generalize to other settings because of contextually-specific cause-composition of mortality, culturally-specific perceptions of health and varying social patterning of health-related attributes. In the West, cardiovascular disease is the leading cause of death, but cancer is the leading cause of death in Hong Kong (Lozano et al., 2013). Moreover, self-ratings tend to be optimistic in the West (Heistaro et al., 2001, Montlahuc et al., 2011) but other cultures may favor moderation, such as the Chinese “doctrine of the mean” (Leung, 2010, Li et al., 2004, Moore, 1967) which may make people rate their health as “normal”. Finally, socioeconomic patterning may be less entrenched in settings where economic development is recent (Maddison, 2007) and socioeconomic disadvantage has not been perpetuated over generations. Few studies have addressed the association of SRH with mortality in non-Western settings, often with short follow-up and small samples (Ho, 1991, Leung et al., 1997). We have previously reported that age-comparative SRH was more strongly associated with concurrent physical conditions than self-comparative SRH (Li et al., 2006) as well as that depression was associated with SRH and mortality (Sun et al., 2013). Here, we examined the role of SRH in predicting death from all- and specific causes in a developed non-Western setting, where cardiovascular disease is not the leading cause of death (Lozano et al., 2013), cultural preferences emphasize moderation (Leung, 2010, Moore, 1967) and universal education is recent (Johnson, 1998). We also examined whether any associations varied by socioeconomic position.