Use Slopes to Track the “Fundamental Cause” of Group Disparities in Health Linda S. Gottfredson University of Delaware Newark, DE USA International Society for Intelligence Research Madrid, December 19, 2009

“Fundamental cause” The relation between social class and health is so general (cannot be explained by income, access to care, etc.) that there must be a highly generalizable “fundamental cause” A highly generalizabl e cause accounting for the remarkably general relation between

g as the “fundamental cause” Hypothesis: – group differences in g are the fundamental cause of group differences in health Common “disproof:” – “If correct…one might have expected the relation between IQ and mortality to act through known risk factors. This does not appear to be the case. In fact, a recent analysis…shows that this relationship is abolished when education and income are in the same model” (Marmot & Kivimaki, 2009)

4 Example: Disparities in health behavior by education; all races & sexes: % who smoke, 2006 (age adjusted) (CDC, Health in the United States, 2008, Table 64) % Education LoHi

Lung cancer mortality, Men 25-64, by social class of county, USA (age adjusted) Gradients sometimes flip over

6 Typical health disparities by education; in all races & sexes: % of non-ill 51-year-olds expected to have this chronic illness by age 63 (USA, ages in 1992; Hayward et al, 2000 ) Hypertension Diabetes white COPD black Cancer Men Women % Years Negative gradients—rare

7 Hypertension Diabetes white COPD black Cancer Men Women % Years Race difference —hypertension Sex difference —diabetes Common policy goal : All gradients flat

88 “Disparity” = group differences on health outcome X “Explaining” between-group variation Means, rates, etc. 16 yrs 12 yrs 8 yrs

99 “Disparity” = group differences on health outcome X “Explaining” between-group variation Means, rates, etc. 16 yrs 12 yrs 8 yrs

10 a b c d d f g This is not about individual differences in health Not “explaining” within-group variation Within-group and between-group variance may arise from different mix of causes

11 Many families of health disparities HEALTH HABITS MORTALITY KNOWLEDGE CHRONIC ILLNESSES INJURIES INFECTIOUS DISEASES ADHERENCE

Example 1 (Erikson & Torssander, 2008) Mortality in Sweden, Among all individuals ages in 1990 So– born ; still alive 1990 died ~ ages (N ~ 130,000 deaths) Social class = occupational level (1-6) Universal health care Ethnically homogeneous Whole cohort (not sample) Uniform classification of deaths Removes 2 common sources of variance in disparities Reduces error variance

Broad categories of death , Sweden Social class disparities among individuals ages in 1990 Causes (selected) Men (N=80,040) Women (N=49,654) Hazards ratios by social class% % (lo) 2345 Neoplasms Infections Nervous system Circulatory Musculoskeletal < External Respiratory Endocrine Mental/behav TOTAL (Erikson & Torssander, 2008) 1=Higher managerial/professional, 2=lower managerial/professional, 3= intermediate, 4=lower supervisory/skilled manual, 5=routine non-manual, 6=unskilled manual

Three major causes of death , Sweden Social class gradients for individuals ages in 1990 Hi Occupational class Lo Hazards ratio

Three major causes of death , Sweden Social class gradients for individuals ages in 1990 Hi Occupational class Lo Hazards ratio Slope (ß)

Causes of death , Sweden Social class disparities among individuals ages in 1990 Causes (selected) Men (N=80,040) Women (N=49,654) Hazards ratios by social class%Slope ( ß ) Hazards ratios by social class%Slope ( ß ) (lo) 2345 Neoplasms Infections Nervous system Circulatory Musculoskeletal < External Respiratory Endocrine Mental/behavioral TOTAL (Erikson & Torssander, 2008) 1=Higher managerial/professional, 2=lower managerial/professional, 3= intermediate, 4=lower supervisory/skilled manual, 5=routine non-manual, 6=unskilled manual Slopes = linear regression of HRs on class categories

Distribution of all 101 class-mortality slopes (50 men, 51 women) NOT independent (includes broad categories plus high-volume sub-categories) Slopes (ß) Mean =.16 SD = But recall population— Universal health care Ethnically homogeneous Cohort born Died ~ ages Need to explain this variation (in gradients)

Distribution of class-mortality slopes Ages in 1990, died , Sweden Men: Women: Men: Women: 35 specific causes of death 15 broad categories of death - + slopes Variability in size of gradients across causes

Distribution of class-mortality slopes Ages in 1990, died , Sweden Men: Women: Men: Women: 35 specific causes of death 15 broad categories of death - + slopes More variability across specific causes

Distribution of class-mortality slopes Ages in 1990, died , Sweden Men: Women: Men: Women: 35 specific causes of death 15 broad categories of death - + slopes Mean SD Sex differences in class gradients

Plot of slopes for men vs. women, broad categories of death Women Men r =.38 = all deaths Hazards ratios range from 1.3 to 5.3

Plot of slopes for men vs. women, specific categories of death (where N > 100, each sex) r =.86 Men Women Hazards ratios range from 0.9 to 6.3 Steeper for women Steeper for men

Class gradients: Specific neoplasms Neoplasms Women Men = All neoplasms

Class gradients: Specific neoplasms Women Men colon lymph skin pancreas rectum kidney bladder esophagus liver stomach lung, larynx lip/oral = All neoplasms

Women Men colon lymph skin pancreas rectum kidney bladder esophagus liver stomach larynx lip/oral = All neoplasms breast, ovary prostate other uterus cervix

Class gradients: Specific circulatory causes Circulatory Women Men = All circulatory

Class gradients: Specific circulatory causes Circulatory Women Men other heart stroke heart attack = All circulatory

Class gradients: Specific external causes External Women Men = All external injuries & accidental poisoning

Class gradients: Specific external causes External Women Men homicide suicide falls accidental poisoning undetermined intent traffic accidents

Sudden cause (“external”) Age of sample matters Causes of death differ by age: males in USA (CDC, Health data interactive) Incubating cause (“internal”) Swedish sample

Specific causes in other broad categories (digestive, endocrine, mental, respiratory) Women Men diabetes alcohol ulcer asthma pneumonia chronic liver disease chronic lower respiratory Other specific causes drug dependence

Most frequent specific internal causes of death: All are “entirely preventable” by patient (Eurostat report) Women Men ulcer asthma pneumonia chronic liver disease esophagus lung, larynx lip/oral colon pancreas kidney bladder skin stomach breast, ovary other uterus cervix prostate chronic lower respiratory diabetes stroke alcohol drug dependence % other heart heart attack homicide suicide falls accidental poisoning undetermined intent traffic accidents 5

Example 2 (Gottfredson, 2004) Mortality in US, All ages External causes only Social class = neighborhood income level (1-6) Differential access to health care Ethnically diverse

Slopes (ß) Mean =.12 SD = Class-mortality gradients, for 55 specific external causes, US population, classes = 6 levels of neighborhood income

Suicide Drugs, alcohol, poisons Falls Homicide Undetermined intent: firearm, poison Vehicles/pedestrian, drowning Burns, cold, choke, neglect, firearm Cut, crushed, machines, electric Slope Class-mortality gradients, by general type of external cause, US population, classes = 6 levels of neighborhood income Mean elderly Working- age men

Suicide Drugs, alcohol, poisons Falls Homicide Undetermined intent: firearm, poison Vehicles/pedestrian, drowning Burns, cold, choke, neglect, firearm Cut, crushed, machines, electric Slope Class-mortality gradients, by general type of external cause, US population, classes = 6 levels of neighborhood income Mean M F F M M M F F F, M = Swedish mean slopes

Changes in: Options & information: preventability (don’t smoke) detection (pap smear) controllability (diet, insulin) Population composition: age cohort ethnicity Slope Source of hypotheses I: Migration of slopes over time and cohorts Meta-analysis of slopes

PredictorsDistribution of: Host exposurePassive (hazards)Active Personal choice Host susceptibilityBiological Cognitive g (or surrogates) Vector burdenBiological (virulence)Cognitive Task complexity Statistical artifactsSampling error Measurement error Restriction in range 38 Source of hypotheses II: g theory + epidemiological perspective

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