Gender difference in the effects of self- rated health on mortality among the oldest-old in China Jiajian Chen 1 Zheng Wu 2 1 East-West Center, Honolulu, Hawaii 2 University of Victoria, Victoria, Canada

Background information Self-rated health (SRH): a robust indicator of overall health status; a powerful predictor of mortality, especially among old persons; a cost-effective and uncomplicated means for assessment.

SRH-mortality relationship inconclusive gender difference in predictability of mortality; causal relationship between health and mortality among the elderly; role of socioeconomic and psychosocial factors in mediating the relationship between SRH and mortality at old ages

Objective of the study To assess gender-specific effects of SRH, education and psychosocial factor on mortality among the oldest-old in China.

Major questions Is SRH predictive of gender-specific mortality among the oldest-old in China? Do risk factors mediate the relationship between SRH and mortality? Is SRH a valid evaluation of health?

Data The Chinese Longitudinal Healthy Survey (CLHLS) of seniors aged 80 or older: 1998 baseline interview survey: 9,073 seniors sampled from rural and urban areas of 22 provinces; 2003 follow-up survey: Of 8,805 respondents aged at baseline, 7,938 respondents who answered SRH by themselves were included in the sub-sample.

Outcome variable Survival time: Death occurred since baseline survey by month; Individuals who still survived at follow-up are treated as censored;

Predictor variables Self-rated health (SRH) based on “how do you rate your health at present?” Good = very good/good; Fair = so-so; Poor = bad/very bad. Interviewer-rated health (IRH): Surprisingly healthy = no obvious ailments; relatively healthy = minor ailments; Ill = moderately ill/very ill. Sex, age, urbanity, marital status, activity of daily living, types of chronic illnesses, and feeling lonely.

Method Life table method: to estimate gender-specific cumulative mortality by SRH. Proportional hazard regression models: to estimate the “net effect” of the SRH on relative risk of mortality controlling for age by single yr (model 1); age, yrs of schooling, marital status, urbanity, ADL, functional condition, chronic conditions, and feeling lonely score (model 2).

Results (1) SRH is predictive of gender-specific mortality among the oldest-old in China …

Cumulative mortality by SRH among the oldest-old in China % % Men Women

Adjusted hazard ratios of mortality for SRH Characteristics Model 1 Model 2 (reference group) Risk ratio Risk ratio Gender (Women) Men 1.1* 1.4* SRH (Good) Fair 1.3* 1.2* Poor 1.6* 1.2* Gender x SRH Gender x Fair 1.3* 1.2* Gender x Poor 1.5* 1.5* *: p<0.05

Results (2) Risk factors do mediate the SRH-mortality relationship among the oldest-old in China …

Age-adjusted hazard ratios of mortality for SRH Characteristics Risk ratio (reference group) Men Women Age 1.08* 1.08* SRH (Good) Fair 1.59* 1.27* Poor 2.43* 1.61* *: p<0.05

Fully adjusted hazard ratios of mortality for SRH Characteristics Risk ratio (reference group) Men Women SRH (Good) Fair 1.43* 1.18* Poor 1.68* 1.21* Years of schooling 0.97* 0.96* Feeling lonely score 1.08* 1.06* *: p<0.05

Results (3) SRH is a valid evaluation of health among the oldest-old in China …

Age-IRH-adjusted hazard ratios of mortality for SRH Characteristics Risk ratio (reference group) Men Women Age 1.07* 1.07* SRH (Good) Fair 1.32* 1.08 Poor 1.46* 1.19* IRH (Surprisingly healthy) Relative healthy 1.51* 1.37* Ill 2.75* 2.24* *: p<0.05

Fully adjusted hazard ratios of mortality for SRH & IRH Characteristics Risk ratio (reference group) Men Women SRH (Good) Fair 1.30* 1.08 Poor 1.30* 1.03 Years of schooling 0.98* 0.96* IRH (Surprisingly healthy) Relative healthy 1.37* 1.27* Ill 2.06* 1.79* *: p<0.05

Limitations No imputation for missing cases and thus may underestimate the strength of association between SRH and mortality among the oldest-old; Missing on SRH is often ADL dependent; Missing on physical health and psychosocial factors is often ill and illiterate. A follow-up longer than 2 yrs may be desirable; Educational level of the oldest-old is low, especially for women.

Summary SRH is a robust indicator for health and longevity among the oldest-old in China; SRH gradient in longevity persists in each age group although it is stronger among oldest-old men than among women; Education and feeling lonely psychosocial factor also have independent effects on longevity.

Policy implications As education and feeling lonely are modifiable factors for oldest-old mortality, social causation plays an important role at old age in China; Educational level is improving, so does the longevity in the new oldest-old generations; In the meantime, increased needs for health care and psychosocial support for the elderly in the near future are inevitable.