Gender difference in the effects of self-rated health on mortality among the

oldest-old in China

Jiajian Chen1

Zheng Wu2

1East-West Center, Honolulu, Hawaii2University 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 80-105 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

0

10

20

30

40

50

60

70

80

0 2 4 6 8 10 12 14 16 18 20 22 24

Month since baseline survey

% %

Men Women

0

10

20

30

40

50

60

70

80

0 2 4 6 8 10 12 14 16 18 20 22 24

Month since baseline survey

PoorFairGood

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.