Global Health & Social Determinants of Health

Introduction: Global Health

Global health is the study and practice of improving health and achieving equity in health for all people worldwide. It recognises that health problems transcend national borders — whether through infectious disease spread, shared environmental challenges, global supply chains, or migration. Key global health concepts include the burden of disease, the epidemiological transition, sustainable development goals, and the social determinants of health.

The WHO Sustainable Development Goals (SDGs)

The United Nations Sustainable Development Goals (SDGs), adopted in 2015, replaced the Millennium Development Goals (MDGs) and provide a framework for global development to 2030. There are 17 SDGs and 169 targets.

SDG 3 — Good Health and Well-Being: the primary health-related goal. Key targets include:

• Reduce global maternal mortality ratio to < 70 per 100,000 live births
• End preventable deaths of newborns and children under 5
• End the epidemics of AIDS, tuberculosis, malaria, and neglected tropical diseases
• Reduce premature mortality from NCDs by one-third through prevention and treatment
• Achieve universal health coverage (UHC)
• Achieve access to safe, effective, quality, and affordable essential medicines and vaccines

Health-related targets across other SDGs:

• SDG 1 (No Poverty): poverty drives poor health
• SDG 2 (Zero Hunger): malnutrition underpins child mortality, stunting, and infection susceptibility
• SDG 6 (Clean Water and Sanitation): unsafe water and sanitation cause ~1.5 million diarrhoeal deaths/year
• SDG 13 (Climate Action): climate change is a health emergency
• SDG 10 (Reduced Inequalities): health inequity mirrors broader inequality

Universal Health Coverage (UHC): the principle that all people can access the health services they need — including prevention, promotion, treatment, rehabilitation, and palliative care — of sufficient quality, without suffering financial hardship. NZ achieves strong UHC through its publicly funded system; the challenge is ensuring access for Māori, Pacific, rural, and low-income populations.

The Epidemiological Transition

The epidemiological transition (Omran, 1971) describes the historical shift in disease patterns from infectious and nutritional diseases to non-communicable, chronic diseases as countries develop economically.

Stage 1 — Age of Pestilence and Famine: high mortality from infectious disease, famine, and malnutrition. High birth rates offset high death rates; life expectancy 20–40 years. Characteristic of pre-industrial societies and the poorest LMICs today.

Stage 2 — Age of Receding Pandemics: mortality from infections declines due to improved nutrition, sanitation, and public health (before effective antibiotics or vaccines). Life expectancy rises to 30–50 years.

Stage 3 — Age of Degenerative and Man-Made Diseases: NCDs (CVD, cancer, diabetes) dominate. Fertility falls; population ageing. Life expectancy 50–70+ years. Most high-income countries today.

Stage 4 — Age of Delayed Degenerative Diseases: NCDs continue to dominate but occur later in life due to improved treatment (statins, antihypertensives, cancer therapy). Life expectancy 70–80+ years.

"Double burden of disease": many LMICs (including Pacific island nations relevant to NZ) face both stages simultaneously — ongoing infectious disease AND a rapidly rising NCD burden, straining limited health systems.

Social Determinants of Health Framework

The WHO Commission on Social Determinants of Health (CSDH) (chaired by Sir Michael Marmot, final report 2008) provided the most comprehensive global framework for understanding health inequities. Its three key recommendations:

1. Improve daily living conditions: 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 poor daily conditions.
3. Measure and understand the problem and assess the impact of action: national health equity monitoring systems.

The CSDH framework distinguishes:

• Structural determinants: socioeconomic and political context (governance, economic policies, social norms, cultural values) and social position (education, occupation, income, gender, ethnicity/race) — these create the social gradient in health.
• Intermediary determinants: the conditions through which structural position affects health — material circumstances (housing, work environment, food), psychosocial circumstances (stress, social support), health behaviours, and the health system itself.

Key Social Determinants and Their Health Impact

Income and poverty: income is perhaps the strongest social determinant. Low income limits access to nutritious food, adequate housing, healthcare, and education. The "income gradient" in health is continuous — health improves at every step up the income ladder (not just above/below a poverty line). In NZ, child poverty (measured by material hardship and before-housing-cost income measures) disproportionately affects Māori and Pacific whānau. The Child Poverty Reduction Act 2018 requires NZ governments to measure and report on child poverty annually.

Housing: overcrowded, damp, cold, or substandard housing drives respiratory disease, rheumatic fever (GAS transmission), meningococcal disease, mental health problems, and injury. In NZ, a severe housing crisis (unaffordability, low vacancy rates, poor-quality housing stock) affects health, particularly for Māori and Pacific families. Kāinga Ora (formerly Housing NZ) provides social housing.

Education: higher educational attainment is consistently associated with better health outcomes across countries. Education provides health literacy, employment opportunities, income security, and social status. Gaps in educational achievement between Māori/Pacific and NZ European students are a key upstream determinant of adult health disparities.

Food security: sufficient access to nutritious food is essential for health at all ages. Food insecurity drives malnutrition (both under- and over-nutrition), obesity, and T2DM. In NZ, high food prices relative to income affect low-income households. Pacific communities in NZ have high rates of T2DM partly attributable to dietary transitions away from traditional foods.

Employment and working conditions: unemployment is a major health risk (mental health, income loss, social isolation). Precarious employment (zero-hours contracts, casual work) prevents planning and creates chronic stress. Occupational hazards — physical (injury, noise, dust), chemical (solvents, pesticides), and psychosocial (job strain, bullying) — affect worker health. Māori are over-represented in lower-skilled, more physically dangerous occupations.

Pacific Health in NZ: A Special Focus

Pacific peoples (Samoan, Tongan, Fijian, Cook Islander, Niuean, Tokelauan, and other Pacific communities) constitute approximately 8% of NZ's population (~450,000). They experience health disparities similar to but distinct from those of Māori:

• Higher rates of T2DM (~3–4× NZ European), obesity, and cardiovascular disease
• Higher rates of rheumatic fever (second highest after Māori)
• Higher rates of SUDI, respiratory infection, and meningococcal disease in children
• Lower cancer screening uptake
• Higher psychological distress

Determinants: many Pacific families live in NZ's most deprived urban areas (South and West Auckland, South Auckland, Porirua); English is often not the first language; there are strong collectivist cultural values (similar in some ways to Māori whānau concepts); high rates of household overcrowding; and transnational financial obligations (remittances to Pacific home countries) reduce disposable income.

Pacific health services and the Pacific Health Strategy (Le Va, Ola Manuia frameworks) recognise the importance of Pacific-led, culturally appropriate services.