Self-Rated Health in Epidemiological Surveys as a Predictor of Disability and Mortality

1. Self-Rated Health in Epidemiological Surveys as a Predictor of Disability and Mortality Ellen Idler, PhD Institute for Health, Health Care Policy and Aging Research Rutgers University, NJ, USA

2. Ellen L. Idler, Ph.D. Ellen Idler is Professor and Chair of the Department of Sociology, Rutgers University, New Brunswick, NJ, US. She has been interested in self-rated health since graduate school when she read the original Mossey and Shapiro article (AJPH 1982). She has received multiple grants, including a 5-year FIRST Award, from the National Institute on Aging for studies of self-rated health, mortality, and disability. In 1999 she was a visiting professor at the University of Copenhagen, Denmark. Self-ratings of health are an appealing research topic because they support the importance of the lay person’s perspective in health.

3. Learning objectives • To understand that self-ratings of health (SRH) have been studied for decades • To trace the history of the identification of SRH as a predictor of mortality • To report new findings on SRH as a predictor of both mortality and ADL/IADL disability • To suggest new directions for research on the mechanisms through which SRH affects health outcomes

4. Self-Ratings of Health (SRH) All in all, would you say your health is… Excellent, Good, Fair, Poor How would you rate your health at the present time? Excellent, Good, Fair, Poor, Bad How is your health, compared with others your age? Better, Same, Worse

5. Duke Longitudinal Study of Human Aging, 1962 - 1973 • Consistent differences between SRH and physician (MD) rating • Differences tend toward higher SRH than MD rating • Highest SRH (compared to MD rating) among the most elderly • SRH appears to predict future MD ratings better than MD ratings predict future SRH

6. Self-Ratings Predict Mortality In 1982 a Canadian study of a large and representative sample of elderly residents of Manitoba found that SRH was among the strongest predictors of mortality over 7 years, second only to age. The analysis adjusted for individual health status obtained from medical records and self-report of conditions. Even after adjustment for covariates, respondents rating their health Poor were 2.9 times as likely to die as those rating their health Excellent.

7. SRH - Mortality Studies since 1982 • Over 50 prospective, population-based studies to date • From Canada, US, Poland, Israel, England, France, Hong Kong, Sweden, Wales, Netherlands, Australia, Japan, Lithuania, Finland, Denmark, Italy, China, Korea

8. SRH - Mortality Studies since 1982 • Sample sizes: N=421 to 7725 • Follow-up times: 2 to 18 years • Health status covariates: MD Exams, Chronic conditions, Symptoms, ADL disability, Medications, Weight, Blood pressure • Significant OR or HR for “Poor” vs. “Excellent” 1.4 to 93.5

9. Survival, Functional Limitations, and Self-Rated Health in the NHANES I Epidemiologic Follow-Up Study, 1992 Ellen Idler, Louise Russell, Diane Davis Institute for Health, Health Policy and Aging Research Rutgers, The State University of New Jersey American Journal of Epidemiology 2000; 152:874-83

10. NHANES-I Epidemiologic Follow-Up Study(NHEFS Data) • General Medical History Supplement subsample N=6913 • Complex sample design, weighted • Ages 25-74 at baseline • Follow-up 1971-1992 • 3.5% of subsample lost to follow-up

11. NHEFS Data • N=6641, complete data for mortality analysis • Dependent variable: Time-to-death in days • N=4136, complete data for ADL/IADL limitations analysis • Dependent variable: Scale of 23 ADL/IADLs • Stanford Health Assessment Questionnaire • Cronbach’s alpha = .96 (1982), .92 (1992) • Assessed 1982 and 1992 only

12. Self-reported data Chronic conditions 42 items Symptoms 22 items Health practices 6 items Observed data MD examination 17 ICD-8 categories Clinical measurements 4 blood, urine tests blood pressure height, weight NHEFS data

13. Age Overweight SBP >=160 mmHg Heart attack Stroke Protein, sugar in urine Shortness of breath Current smoker No exercise Self-rated health (SRH) Excellent .52 Very good .56 Good .68 Age MD: Circulatory disease Underweight Hematocrit >43% SBP = 140-159 mmHg SBP >= 160 mmHg Protein, sugar in urine Current smoker No exercise Males Females Mortality Hazard Ratios (p<.05)

14. Age Bronchitis Heart attack Hernia (-) Hives (-) Cough Chest pain Pain in legs Self-rated health (SRH) Excellent -5.8*** Very good -5.7*** Good -5.4** Fair -4.1* Age MD: Circulatory disease MD: Musculoskeletal disease Overweight Arthritis Diabetes Heart attack Cough Pain in legs Wheezy chest Drinks weekly (-) Self-rated health (SRH) Excellent -8.1*** Very good -7.1*** Good -8.1*** Fair -3.9* ADL/IADL limitations analysis (p<.05) Females Males

15. Conclusions • Data quality • includes both self-report and MD exam • unlikely to be surpassed in US studies in future • Multiple endpoints for analysis • Mortality - includes entire sample • ADL/IADL limitations - discriminates among survivors • Gender differences • implications for future research