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Determinants of health and disease. Cesar Victora Universidade Federal de Pelotas Washington, June 2002. Structure of presentation. Populations and individuals Approaches to understanding determinants of health and disease Life-course approaches Challenges for the future.

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Determinants of health and disease

Cesar Victora

Universidade Federal de Pelotas

Washington, June 2002


Structure of presentation

  • Populations and individuals

  • Approaches to understanding determinants of health and disease

  • Life-course approaches

  • Challenges for the future


Determinants of health and disease

Models of disease causation


Sick individuals and

sick populations

G. Rose, 1985


Determinants of individual cases

measured through relative risk

depend on heterogeneity of exposure

may miss most important causes if highly prevalent

Determinants of population incidence rates

identified through ecologic comparisons of exposure and disease distributions

Sick individuals and sick populationsG. Rose, 1985


Mosley-Chen analysis

Mosley and Chen, 1983


Social sciences approach

emphasis on distal determinants

political and ideological structure

socioeconomic status

behavioral factors

Biological sciences approach

emphasis on proximate determinants

water/sanitation

environment

immunity

genetic factors

etc

Traditional approaches to understanding determination of health status

Mosley and Chen, 1983


Unicausality

one germ, one disease

around 1900

Agent/ host/ environment interaction

1930’s-1940’s

the agent alone has limited explanatory power

Multicausality

1960’s

each disease may have several different causes

“web of causation”

Genomic era

1990’s

renewed emphasis on individual susceptibility

Biological sciences approaches


Emphasis on individuals

No hierarchy among causes

No discussion of the causes of causes

Emphasis on finding technological solutions (“magic bullets”)

Effective for controlling many diseases

vaccine preventable diseases

micronutrient deficiencies

etc

Biological sciences approaches


Mosley-Chen model for child health

Mosley and Chen, 1983


McMahon et al, 1960: Epidemiologic Methods

  • Introduced concept of “web of causation”

  • Advice:

    • abandon semantic exercises aimed at hierarchic classification of causes

    • seek the necessary causes most amenable to practical intervention and nearest to the specified outcome


Epidemiology and the web of causation: has anyone seen the spider?

  • Models do not exist independent of theories

  • The underlying model of the causal web is biomedical individualism

    • the logical solutions are biomedical interventions at individual level

  • Web approach

    • gives equal weight to factors that are hierarchically different

    • does not differentiate between determinants at individual and population level

Source: Krieger N, 1994


Health Inequality Research in Latin America and Caribbean

Almeida, Kawachi, Pellegrini, Dachs (in press)


Health Inequality Research in Latin American Countries

Almeida, Kawachi, Pellegrini, Dachs (in press)


Scandinavian countries

Gini’s index =0.25

World’s 10 most unequal countries

Gini’s index

for income

concentration

UNDP 2001


Emphasis on population level determinants

Structural factors (economic, political and social) are the main determinants of health status

social class

Mixed reliance on empirical and quantitative approaches

Latin American scientific production is almost “invisible” in North America and Europe (Breilh, 1995)

The Latin American Social Epidemiology Movement


AInequity continues to be the leading health problem in the Americas”

Pan-American Health Organization (1998).

Leading Pan-American Health.

Washington: PAHO (Official Document no. 287).


Determinants of health and disease

A model for child health


ADVOCACY

POLITICAL ACTION

Distal/socioeconomic

Income Land Tenure

Parental Education Employment, etc

Intermediate/environmental

Intermediate/behavioral

Water, sanitation

Housing

Indoor pollution

Crowding

Food availability

COMMUNITY-LEVEL

INTERVENTIONS

Risk behaviors

Preventive behaviors

Careseeking

Home management

of disease

SERVICES

DELIVERY

Proximate/biological

Nutritional status

Disease incidenceDisease severity

Child health/disease

Economic structure

Political and ideological superstructure

Macroenvironment

Government

policies and

actions

Non-health-sector

interventions

Health-sector

interventions

preventive

curative

Global power relations

International trade

and investments

Globalization

GENETIC

FACTORS


Infant mortality in selected Latin American countries, 1960-94

Source: Dachs N, PAHO


IMR and land tenure:advocacy


Two hierarchies


1. Unit of aggregation

Global

National

State/provincial

Community

Household

Family

Individual


The different levels of inequities

  • “An association between socioeconomic deprivation and ill-health has been found wherever and whenever it has been looked for”(Sir Douglas Black, 2001)

  • “and at whatever level of aggregation it has been investigated”


Distal/socioeconomic

Income Land Tenure

Parental Education Employment, etc

Intermediate/environmental

Intermediate/behavioral

Water, sanitation

Housing

Indoor pollution

Crowding

Food availability

Risk behaviors

Preventive behaviors

Careseeking

Home management

of disease

Proximate/biological

Nutritional status

Disease incidenceDisease severity

Child health/disease

2. Level of determination

Individual


In summary

  • Studies of determinants of health must address different levels of aggregation

    • populations

    • sub-populations

    • individuals

  • Hierarchies between levels and among determinants are important

  • Multiple disciplines are required for a thorough understanding of health determinants

  • Actions to improve health must address different levels of determination


Determinants of health and disease

The life-course approach


The 1982 Pelotas Birth Cohort Study

  • Population-based cohort of 6,000 children

  • Follow up from birth to 19 years

  • Probably longest and largest birth cohort from a developing country


1982 Birth Cohort

1982

2000


Field work in

Pelotas,

1980’s


Cohort visits


Lack of antenatal care, 1982


Infant mortality, 1982


Stunting prevalence at 20 months, 1984


Summary of early findings on socioeconomic inequities, 1982-86

  • Children from low income families had the worst health indicators, except for

    • caesarean sections

    • overweight


Achieved schooling by year 2000 (boys)

P<0.001


Risk factors for chronic diseases in 2000 (boys)

MONTHLY INCOME (US$)

All P<0.01, except * (0.1>P>0.05)


Teenage pregnancies


Teenage pregnancies by 2000 according to family income (1982)

n=443

P<0.001


Mean birthweight of children of adolescents, according to mother’s birthweight, 1982

3259 g

n=406

P<0.001

2922 g


Low birthweight in two generations by income in 1982


The catch-up dilemma


Hospital admissions (1985) according to growth in 1982-84 (0-20 months)

P<=0.03

Victora, Barros et al (IJE 2001)


Mortality from 20-59 months according to growth in 1982-84 (0-20 months)

Based on

10 deaths,

P=0.045

Victora, Barros et al (IJE 2001)


Obesity and overweight in 18-year-old boys according to growth from 0-20 months

P<0.001

Victora, Barros et al (IJE 2001)


Asthma: the Hygiene Hypothesis


Asthma prevalence in 18-year-old boys by income in 1982

P=0.01

Lima, Victora et al (in press)


Risk factors in childhood reduce asthma in adolescence

Analyses adjusted for socioeconomic

confounders; all P<0.05

Lima, Victora et al (IJE 2001)


Summary of life-course results from Pelotas

  • Inequities by late adolescence are complex due to the nutrition and epidemiologic transitions

  • Risk factors in pregnancy and childbirth tend to repeat themselves in subsequent generations

  • Risk factors for infectious diseases in early life may protect against chronic diseases later on


Conclusions


Future challenges

  • Understanding the interplay of population and individual level determinants

    • the role of context

    • multi-level analyses

  • Studying disease determinants in a changing world

    • need for more life-course studies in LDC’s

  • Translating knowledge into action

    • developing both a scientific and an advocacy agenda

    • interacting with the communities to which we belong


End


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