Social Determinants of Health

Social determinants of health (SDH) are the non-medical conditions in which people are born, grow, live, work and age, and the wider forces that shape these conditions. For NEET PG, this is a conceptually rich, recurring Community Medicine area: the WHO CSDH framework, the Lalonde model, the social gradient (Marmot), the Gini coefficient, and the crucial equity vs equality distinction are all directly examinable.

Definition and the big picture

The WHO defines social determinants of health as "the conditions in which people are born, grow, live, work and age, and the wider set of forces and systems shaping the conditions of daily life." These forces include economic policies, development agendas, social norms, social policies and political systems.

A widely quoted estimate (Dahlgren–Whitehead / WHO) holds that medical care contributes only ~10–20% to population health outcomes, while social, behavioural and environmental determinants account for the remaining ~80–90%. This single fact reframes public health: investing only in hospitals will never close health gaps because most of the "causes of the causes" lie upstream.

High-yield: SDH are responsible for the bulk of health inequities — the unfair and avoidable differences in health between population groups. The phrase "causes of the causes" (Marmot) refers to SDH acting behind proximate medical causes.

The classic visual is the Dahlgren and Whitehead "rainbow" model (1991), a set of concentric layers around the individual:

1. Age, sex and constitutional (genetic) factors — fixed core, non-modifiable.
2. Individual lifestyle factors — smoking, diet, physical activity.
3. Social and community networks — social capital, support.
4. Living and working conditions — housing, water, sanitation, education, healthcare, employment, agriculture/food.
5. General socioeconomic, cultural and environmental conditions — the outermost macro layer.

The Lalonde model (Health Field Concept)

The Lalonde Report (1974, Canada) — "A New Perspective on the Health of Canadians" — was the first government document in a modern industrialised country to formally acknowledge that medical care is not the main determinant of health. It proposed the Health Field Concept with four determinants ("fields"):

Lalonde field	What it covers	Approx. relative contribution*
Human biology	Genetics, ageing, internal body systems	~20%
Environment	Physical + social + psychological surroundings (water, air, housing)	~20%
Lifestyle / behaviour	Self-imposed risks: diet, smoking, exercise	~50% (largest)
Health care organisation	Quality, quantity, availability of medical services	~10%

*The exact percentages vary by source; what is reliably tested is that lifestyle is portrayed as the single largest contributor and health care organisation the smallest.

High-yield: Mnemonic for the Lalonde four fields — "BELH" → Biology, Environment, Lifestyle, Health care organisation. Remember "Lifestyle is Largest."

The Lalonde model is the historical ancestor of the modern SDH concept and is frequently asked as a single-best-answer ("Which is the largest determinant in the Lalonde/Health Field concept?" → Lifestyle).

The WHO Commission on Social Determinants of Health (CSDH)

The WHO Commission on Social Determinants of Health was established in 2005, chaired by Sir Michael Marmot, and delivered its landmark final report "Closing the gap in a generation" in 2008.

The three overarching recommendations of the CSDH (2008)

1. Improve the conditions of daily life — the circumstances in which people are born, grow, live, work and age.
2. Tackle the inequitable distribution of power, money and resources — the structural drivers of those conditions, globally, nationally and locally.
3. Measure and understand the problem and assess the impact of action — expand the knowledge base, develop a trained workforce, raise public awareness.

High-yield: The CSDH was created in 2005, reported in 2008, was chaired by Marmot, and its report was titled "Closing the gap in a generation." Expect a one-liner asking for the year, the chair, or the report name.

The CSDH conceptual framework: structural vs intermediary determinants

This is the single most tested part of the topic. The CSDH framework divides determinants into two layers connected by the central concept of socioeconomic position.

Feature	Structural determinants	Intermediary determinants
Also called	"Social determinants of health inequities"	"Social determinants of health" (proximal)
Position	Upstream / macro	Downstream / proximal
Components	Socioeconomic & political context (governance, macroeconomic & social policies, public policy, culture & societal values) + socioeconomic position (income, education, occupation, social class, gender, race/ethnicity)	Material circumstances (housing, food, work environment); behaviours & biological factors; psychosocial factors; the health system itself; social cohesion / social capital
Role	Generate and reinforce stratification; shape an individual's social position	Reflect the position; act as the pathways through which structural factors affect health
Examples	Caste system, education policy, tax/welfare policy	Damp housing, malnutrition, occupational hazard, stress

The flow of causation:

Socioeconomic & political context → Socioeconomic position (class, gender, ethnicity, income, education, occupation) → Intermediary determinants (material, behavioural, psychosocial, biological) + Health system → Distribution of health and well-being (equity).

Two cross-cutting elements sit across the framework: social cohesion and social capital (which bridge structural and intermediary levels). The model is bidirectional — ill-health can feed back and worsen a person's socioeconomic position (e.g., catastrophic health expenditure pushing families into poverty).

High-yield: Income, education, occupation, social class, gender and ethnicity/caste are STRUCTURAL determinants (they fix social position). Housing, behaviour, working conditions, psychosocial stress and the health-care system are INTERMEDIARY determinants (the pathways). This structural-vs-intermediary classification is the highest-yield single fact of the topic.

The Marmot reviews and the social gradient

Sir Michael Marmot's work, especially the Whitehall studies of British civil servants, produced the defining empirical observation: the social gradient in health.

• The social gradient means health follows a graded, stepwise relationship with socioeconomic position — it is not simply "poor vs rich." Each step up the social ladder is associated with better health than the step below, all the way to the top.
• In Whitehall, even senior administrators (well-paid, not poor) had worse cardiovascular mortality than those one rung above them. Health is therefore worse at every lower grade, in a continuous gradient.

The Marmot Review (2010), "Fair Society, Healthy Lives," applied SDH thinking to England and introduced proportionate universalism: actions must be universal (for everyone) but delivered with a scale and intensity proportionate to the level of disadvantage — purely targeting the poorest misses the gradient.

It proposed six policy objectives, the most quoted being "Give every child the best start in life," ranked as the highest priority.

High-yield: The social gradient is graded across the whole society, not a poor/non-poor dichotomy. Proportionate universalism = universal services scaled to need. "Best start in life" is Marmot's top recommendation.

Income inequality and the Gini coefficient

Income distribution is a structural determinant. The Gini coefficient is the standard summary measure, derived from the Lorenz curve.

• The Lorenz curve plots the cumulative share of total income (y-axis) against the cumulative share of population from poorest to richest (x-axis). The line of equality is the 45° diagonal.
• The Gini coefficient = area between the line of equality and the Lorenz curve ÷ total area under the line of equality.

Gini value	Interpretation
0	Perfect equality (everyone has identical income)
1 (or 100%)	Perfect inequality (one person has all income)
Lower value	More equal society
Higher value	More unequal society

High-yield: Gini = 0 → perfect equality; Gini = 1 → perfect inequality. It is calculated from the Lorenz curve. A higher Gini means a more unequal income distribution.

The related thesis (Wilkinson & Pickett, "The Spirit Level") is the income inequality hypothesis: beyond a threshold, it is the relative inequality within a society — not just absolute poverty — that drives worse health outcomes (higher mortality, mental illness, violence). This explains why some richer but more unequal nations have worse population health than poorer but more equal ones.

Health equity vs equality vs equity — the core distinction

This distinction is examined almost every cycle and is often misanswered.

Term	Meaning	Example
Health equality	Everyone gets the same resource/input, regardless of need	Same number of doctors per district everywhere
Health equity	Resources distributed according to need, to achieve fair outcomes; removal of unfair, avoidable differences	More health workers posted to a high-burden tribal district
Health inequality	Any measurable difference in health between groups (may be natural/unavoidable)	Older people have more disease than younger
Health inequity	A subset of inequalities that are unfair and avoidable, rooted in social injustice	Higher maternal mortality among Dalit women

The classic image: giving every child the same-height box to see over a fence is equality; giving each child a box sized to their height so all can see is equity.

High-yield: Equality = same input to all. Equity = input according to need to reach a fair outcome. All inequities are inequalities, but not all inequalities are inequities (only the unfair, avoidable ones). Horizontal equity = equal treatment for equal need; vertical equity = greater (different) treatment for greater need.

SDH in the Indian context: caste, gender and intersectionality

India's SDH operate through deeply rooted structural axes. Intersectionality (term coined by Kimberlé Crenshaw) describes how multiple identities — caste, gender, class, religion, disability — overlap to compound disadvantage; the effect is multiplicative, not additive.

Indian illustrations frequently used in exams:

• Caste: SC/ST populations show higher infant and under-5 mortality, higher stunting/undernutrition, lower institutional delivery rates, and poorer access to sanitation than the general population (consistently shown in NFHS data).
• Gender: Adverse child sex ratio (sex-selective practices), higher female anaemia, restricted health-seeking autonomy, and the "missing women" phenomenon (Amartya Sen).
• Poverty: Catastrophic health expenditure and out-of-pocket spending push tens of millions into poverty annually — a key bidirectional SDH loop.
• Intersection: A poor, rural, Dalit woman faces the worst composite outcomes — illustrating intersectionality in practice.

Policy responses framed as acting on SDH: NRHM/NHM, ICDS (best start in life), POSHAN Abhiyaan, Swachh Bharat Mission (sanitation as an intermediary determinant), Ayushman Bharat / PM-JAY (financial protection), and MGNREGA (income — a structural lever).

High-yield: Intersectionality (Crenshaw) = overlapping identities (caste + gender + class) compounding disadvantage. The most disadvantaged Indian health profile in MCQs is the poor rural Dalit/tribal woman.

Pathways and mechanisms (how SDH "get under the skin")

How do upstream conditions translate into disease? The CSDH and allied literature describe several pathways:

1. Material pathway — lack of money → poor nutrition, unsafe housing, no clean water → infection, undernutrition.
2. Behavioural pathway — disadvantage clusters risky behaviours (tobacco, alcohol, poor diet).
3. Psychosocial pathway — chronic stress, low control (Whitehall) → neuroendocrine activation → cardiovascular and metabolic disease. The concept of allostatic load (cumulative biological "wear and tear" from chronic stress) is the biological mechanism here.
4. Life-course pathway — early-life exposures (Barker hypothesis / DOHaD — low birth weight → adult cardiovascular disease) have lifelong consequences, hence "best start in life."

High-yield: Allostatic load = cumulative physiological burden of chronic stress; links low social position (low control) to disease via the psychosocial pathway.

Key differentials / commonly confused pairs

Examiners exploit confusion between near-identical concepts:

• Structural vs intermediary determinant — see the table above; social class/gender/income (structural) vs housing/behaviour/health system (intermediary).
• Equality vs equity — same input vs need-based input.
• Inequality vs inequity — measurable difference vs unfair + avoidable difference.
• Lalonde vs CSDH — Lalonde (1974, four fields, "lifestyle largest") vs CSDH (2005/2008, structural/intermediary, Marmot).
• Horizontal vs vertical equity — equal-for-equal-need vs unequal-for-unequal-need.
• Dahlgren–Whitehead rainbow vs CSDH framework — layered concentric model vs structural/intermediary flow model.
• Gini vs Lorenz — Lorenz is the curve; Gini is the single number derived from it.

Recently asked / exam angle

• "Largest determinant in the Lalonde Health Field concept?" → Lifestyle/behaviour.
• "Which is a structural determinant of health?" → options like education / income / gender / social class (vs distractors like housing or health system, which are intermediary).
• "The WHO CSDH was chaired by?" → Michael Marmot, report 2008, titled "Closing the gap in a generation."
• "Gini coefficient of 0 indicates?" → Perfect equality. Derived from the Lorenz curve.
• "Same resources to everyone irrespective of need is?" → Equality (not equity).
• "Concept of proportionate universalism" → Marmot Review 2010.
• "Causes of the causes" → coined by Marmot, refers to social determinants.
• Image/scenario questions: a graded health–income relationship across all classes → social gradient (Whitehall).
• "Multiple overlapping disadvantages (caste + gender + poverty)" → intersectionality (Crenshaw).
• "Estimated contribution of medical care to health" → ~10–20%.

Rapid revision

1. SDH = conditions in which people are born, grow, live, work, age; medical care contributes only ~10–20% to health.
2. Lalonde (1974) four fields = Biology, Environment, Lifestyle, Health-care organisation — lifestyle is largest, health care smallest.
3. Dahlgren–Whitehead rainbow: innermost layer = age/sex/genetic (fixed); outermost = socioeconomic/cultural/environmental.
4. CSDH: established 2005, reported 2008, chaired by Marmot, report "Closing the gap in a generation."
5. Structural determinants = socioeconomic/political context + position (income, education, occupation, class, gender, ethnicity/caste); they create stratification.
6. Intermediary determinants = material circumstances, behaviour, psychosocial factors, biology, and the health system — the pathways.
7. Social gradient (Whitehall/Marmot) = health worsens at each step down the ladder, across the whole society, not just poor vs rich.
8. Proportionate universalism (Marmot 2010) = universal action scaled to disadvantage; top priority = "best start in life."
9. Gini coefficient: from Lorenz curve; 0 = perfect equality, 1 = perfect inequality; higher = more unequal.
10. Equality = same input to all; equity = input by need for fair outcome; inequity = unfair + avoidable inequality.
11. Intersectionality (Crenshaw) = overlapping caste + gender + class disadvantage; Indian worst profile = poor rural Dalit/tribal woman.
12. Allostatic load = chronic-stress biological burden; Barker hypothesis/DOHaD = early-life origins of adult disease (life-course pathway).