Lecture 2: Introduction to the Epidemiology of Non-Communicable Diseases PDF

Lecture 2: Introduction to the epidemiology of non- communicable diseases Marina Treskova, PhD Head of Research Group Eco-Epidemiology Heidelberg Institute of Global Health & I...

Lecture 2: Introduction to the epidemiology of non- communicable diseases Marina Treskova, PhD Head of Research Group Eco-Epidemiology Heidelberg Institute of Global Health & Interdisciplinary Centre for Scientific Computing Heidelberg University www.hei-planet.com 01/14/2025 Outline Introduction to NCD and GBD Epidemiologic transition NCD risk factors: upstream and downstream Epidemiology of: Reproductive health Cardiovascular diseases and Type 2 diabetes Cancer Respiratory diseases (COPD and asthma) 01/14/2025 What are non-communicable diseases? Term non-communicable diseases covers a very broad range of conditions that are not transmitted from human-to-human Major focus of global NCDs: CVD, cancer, type 2 diabetes mellitus, and COPD Other: injuries, mental disorders, reproductive disorders But can be of infectious agent origin: e.g. HPV Most NCDs increase in prevalence with age and some share common underlying risk factors, making co-morbidities common in older age 01/14/2025 Non-communicable disease epidemiology Tend to focus on specific diseases: cancer epidemiology, cardiovascular epidemiology, respiratory epidemiology - rather than under a common title of non- communicable disease epidemiology. Global non-communicable disease epidemiology: The key determinants of chronic diseases (unhealthy diet, physical inactivity, and tobacco use) are all strongly influenced by globalization. The Global Burden of Disease study: is a comprehensive research initiative that provides systematic and comparable data on health loss due to diseases, injuries, and risk factors across the world. It is one of the most significant collaborative efforts in global health research, involving institutions, researchers, and policymakers worldwide. The data can be examined by anyone and presented in many different ways. 01/14/2025 The Global Burden of Disease Infectious diseases and neonatal conditions dominate the 1990 estimates. In contrast, by 2015 only lower respiratory infections remained in the leading three causes of global DALY: Disability-Adjusted Life Years: A combined measure of premature mortality (Years of Life Lost, YLL) and non-fatal health outcomes (Years Lived with Disability, YLD). Changes in the top 30 causes of death globally between 1990 and 2019 – Disability (DALYs) Source: Global Burden of Disease 2019, DALYs and HALE 01/14/2025 Collaborators, 2020 Epidemiologic transition NCDs rise in nearly all regions of the world as most countries go through the epidemiologic transition. Death rates of communicable disease decline while rates of a wide range of disorders associated with urbanization and affluence increase. WHO: a three-level classification of diseases and mortality: Group 1 : Communicable diseases, maternal, perinatal, and nutritional disorders Group 2 : Non-communicable diseases (defined as neither group 1 or 3) Group 3 : Intentional or unintentional injuries During the epidemiologic transition mortality due to group 1 conditions typically reduced faster than other causes of mortality, and mortality due to group 2 and 3 conditions tend to increase. Public health interventions to prevent and control differ between these groups of conditions. 01/14/2025 Double burden of disease LMIC: the intermediate phases of transition, both communicable and NCDs co-exist - a “double burden” Globally: combined burden requiring resources for prevention, control and paliation Predicted Causes of Death by Region, 2008 and 2030 Source: Reardon, 2011 A world of chronic disease. Science, 333(6042): 558-559. doi: 10.1126/science.333.6042.558. 01/14/2025 NCD risk factors Factors specific to the diseases and Global factors: operate at the global level are not under the control of individuals often are determined by factors outside the control of governments of countries Urbanization: industrialization, modernization and urban culture: Alteration in diets Reduced physical activity Loss of traditional cultural values and behaviors Migration: from rural to urban areas Poverty: Rates of mortality from NCDs are higher in low and middle income countries than they are in high income countries, indicating that aspects of poverty are important in determining the NCD burden. 01/14/2025 NCD: upstream and downstream determinants Upstream determinants of health are classically defined as macro-level factors, such as globalization or communities that influence health. Downstream determinants of health are factors at the individual or micro-level, such as: genetics; age; individual health behaviors (e.g. smoking); or other biological factors, such as blood pressure or lipid levels, that influence health. 01/14/2025 Life-course perspective life-course perspective: how an individual responds to the macro- level factors in life may influence what affect if any these macro-level factors have on an individual's risk for NCDs At any point or age in life, macro-level factors can influence individual health determinants. 01/14/2025 Source: Figure 1 in Glass and McAtee Social determinants of NCD Neighbourhood effects: compositional effects contextual effects: involve social or dynamic features of a neighbourhood, such as social networks or culture integral effects of the neighbourhood: structural characteristics E.g. of social networking effects on obesity in a cohort study: shows how obesity has not only increased over time, but how it is related to the types of people or social networks that one knows. www.nejm.org/doi/full/10.1056/NEJMsa066082 01/14/2025 Built environment and NCD risk factor distributions Built environment: anything human-made in the environment, including parks or lakes. Physical activity and the built environment influences physical activity at the individual level Urban landscape in different settings offers different access to open spaces for exercise, fitness clubs, pedestrian zones, bike lanes and public transportation The food environment location, type, and number of food outlets within a given area what foods are available within a given food outlet, including the quality and price of these foods Food and tobacco labelling are one way that policy affects items within the built environment that affect NCD risk factors 01/14/2025 Trade agreements, nutrition and NCD risk factors Trade agreement: treaties between countries that are related to tax, tariffs, and trade. Trade agreements influence NCD risk factors primarily through their influence on agricultural production; trade in foodstuffs, and food processing. Trade agreements may influence NCD risk through: 1) the environment itself via agricultural production; and 2) the food environment by influencing what is available for consumption. Friel et al. elucidate how global trade influences health by stating three main pathways: 1.Through the production and exchange of goods from agricultural production and trade 2.Through Foreign Direct Investment (FDI) that is related to food processing and the selling of food 3.Through domestic (in-country) trade protections and supports 01/14/2025 Trade agreements, nutrition and NCD risk factors Trade agreements affect NCD risk factor distributions through the direct role they play in shaping the food system by influencing what is produced agriculturally and that then can be used to manufacture processed food products. Source: Friel et al. 2013 01/14/2025 Nutrition transition Taken together, a nutrition transition has occurred in many countries. Source: Popkin, 2003 01/14/2025 Agricultural policies, climate change and NCD risk factors Three main types of agricultural policies: agricultural input policies: enhance agricultural production agricultural production policies: support farmer's incomes while they work in agricultural production agricultural trade policies: promoting and protecting agricultural economic markets 01/14/2025 Agricultural policies and production practices and diet relationship between agricultural policies and production practices and diet 01/14/2025 Source: Hawkes, 2007 Agriculture, climate change and health Livestock production contributes to climate change due to: Deforestation Energy and water consumption Nox emissions 01/14/2025  McMichael et al. “contraction and convergence policy” HIC reduce their consumption of animal source foods to lower the ceiling meat consumption level to which LMIC would converge. impact on NCDs that meat consumption is predicted to have in 2050 if the “contraction and convergence policy” Source: McMichael et al. 2007 01/14/2025 Further outline Epidemiology Reproductive health Cardiovascular diseases and Type 2 diabetes Cancer Respiratory diseases (COPD and asthma)..briefly 01/14/2025  Reproductive health 01/14/2025 Reproductive health Understanding determinants of reproductive health are essential for successful reproduction Achieving good reproductive health is essential to achieving good levels of health for the individual for the population Reproductive health covers biological process of conception, period of pregnancy, childbirth and the neonatal period. Reproductive ill-health examples: Infertility Fetal death Stillbirth Congenital anomaly Abnormal fetal growth Preterm delivery Maternal death Neonatal death 01/14/2025 Reproductive health: Maternal mortality “the death of a woman while pregnant or within 42 days of termination of pregnancy, irrespective of the duration and the site of the pregnancy, from any cause related to or aggravated by the pregnancy or its management but not from accidental or incidental causes” (WHO, 2004). Direct deaths: “…maternal deaths resulting from obstetric complications of the pregnant state (pregnancy, labor, and puerperium), from interventions, omissions, incorrect treatment, or from a chain of events resulting from any of the above ” Indirect deaths: “…resulting from previous existing disease or disease that developed during pregnancy and which was not due to direct obstetric causes but which was aggravated by the physiologic effects of pregnancy ” The maternal mortality ratio = the number of deaths per 100,000 live births per time-period (WHO) 01/14/2025 Reproductive health: estimates of maternal mortality ratio by country Source: WHO, 2015 (www.who.int/reproductivehealth/publications/monitoring/maternal-mortality- 2015/en/) 01/14/2025 Countdown to 2015 for Maternal, Newborn and Child Survival Started in 2003 to track progress towards MDG4 and MDG5 in 75 priority countries where >95% of maternal and child deaths occur Produced seven global reports Final report published in 2015. Re-launched as ‘Countdown to 2030’ countdown2030.org/about-countdown 01/14/2025 Reproductive health: Maternal mortality causes Major causes of maternal deaths (2003 – 2009) were: Maternal haemorrhage Infection (sepsis) Abortion Hypertensive disorders of pregnancy Embolism Other direct causes (complications of delivery, obstructed labour, and all other direct causes) Indirect causes The highest risk of maternal death is within 24 hours of delivery, with approximately two- thirds of maternal deaths occurring within the first week after delivery. Unsafe abortion is considered one of the most preventable causes of maternal death. 01/14/2025 Reproductive health: Early life mortality Indicator Numerator Denominator Reported… Stillbirths (however Stillbirth rate Total number of births (live defined) in a defined time per 1,000 births over the (miscarriage < 1 trim) 2 – births plus stillbirths) over period (eg one calendar time period 3 trimester same time period year) Neonatal deaths in a Neonatal mortality rate (0 Total number of live births per 1,000 live births over defined time period (eg – 27 days old) over same time period the time period one calendar year) Stillbirths (however Perinatal mortality rate defined) and early Total number of births (live per 1,000 births over the (2nd trimester – 7-27 days neonatal deaths in a births plus stillbirths) over time period old) defined time period (eg same time period one calendar year) Infant deaths (neonatal Infant mortality rate (0- and post-neonatal deaths) Total number of live births per 1,000 live births over 364 days old) in a defined time period over same time period the time period (eg one calendar year) 01/14/2025 Reproductive health: Stillbirth - trends Source: Blencowe et al. 2016 A gestational age threshold of ≥28weeks gestation 01/14/2025 Reproductive health: neonatal deaths Neonatal (age 0-27 days) mortality rates by region, 2015 Source: GBD 2015 Child Mortality Collaborators, 2016 Stillbirth was not included in targets for SDGs (or MDGs). 01/14/2025 Reproductive health: stillbirth causes Common causes of stillbirth include: Maternal infections in pregnancy Preterm birth complications (before 37 completed weeks of pregnancy) Intrapartum-related (aka “birth asphyxia”) Complications of childbirth Maternal risk factors and conditions Post-term pregnancy Congenital abnormalities Fetal growth restriction and pre-term labour The importance of individual risk factors varies regionally. Most neonatal deaths occur in the first week of life There is significant overlap between the causes of early neonatal death, stillbirth, and maternal mortality. 01/14/2025  Cardiovascular diseases and Type 2 diabetes 01/14/2025 Cardiovascular diseases and Type 2 diabetes CVD - a wide range of conditions affecting the heart and major blood vessels. CVD include coronary heart disease (leading to myocardial infarction (heart attack)), cerebrovascular disease (leading to stroke), angina and peripheral vascular disease Diabetes: group of conditions in which the body is unable to regulate the level of glucose effectively, leading to high glucose blood levels Type I diabetes - the pancreas stops producing insulin Type II diabetes - the body tissues do not respond to the insulin that is produced by the pancreas - insulin resistance WHO definition: Fasting blood glucose ≥7mmol/l HbA1C >6.5% 01/14/2025 Cardiovascular diseases: the Global Burden of Disease Study (2019). 01/14/2025 Diabetes epidemiology The majority of people with diabetes worldwide have type II diabetes. The incidence of type I diabetes in low-income countries is unclear and where medical facilities are very limited, most affected children will die. Efforts to reduce the mortality from type I diabetes are therefore focused on effective health care delivery. Type II diabetes is in part due to issues such as diet and obesity and there may be scope for prevention using public health measures. The blood glucose levels and types of tests used to define diabetes have changed over time and in many countries have not been measured systematically which have made good quality studies difficult to perform. 01/14/2025 Cardiovascular diseases and T2 Diabetes: factors Many factors including changing lifestyles, the increasing prevalence of risk factors such as smoking and hypertension, and a growing and ageing population. Established risk factors: High blood pressure Obesity Smoking High LDL cholesterol Physical inactivity 01/14/2025 CVD and T2D factors: blood pressure Blood pressure: a higher one (systolic) and a lower one (diastolic). 01/14/2025 CVD and T2D factors: Obesity Obesity - a medical condition in which excess body fat has adverse effects on health Measured using BMI: BMI ≥25 is overweight BMI ≥30 is obesity Figure: blue circles - adjusted for systolic blood pressure, history of diabetes, and cholesterol Hazard Ratios for coronary heart disease across quantiles of baseline BMI Source: The Emerging Risk Factors Collaboration, 2011 01/14/2025 CVD and T2D factors: Smoking Pirie et al. 2013: Relative risk of all-cause mortality over 12 years by amount smoked compared to never smokers Population: women in the UK, 1.2 mln the number of cigarettes per day is linearly related to risk of CVD Smoking is declining in HIC and increasing in LMIC 01/14/2025 CVD and T2D factors: Cholesterol Cholesterol: LDL and HDL Epidemiological studies: higher concentrations of LDL and lower concentrations of HDL are strongly associated with CVD. Suggested that these promote atherosclerosis leading to CVD. There is a continuous linear relationship between cardiovascular risk and level of cholesterol. Hazard ratios for coronary heart disease across quantiles of non-hdl-cholesterol levels 01/14/2025 Source: Emerging Risk Factors Collaboration, 2009  Cancer epidemiology 01/14/2025 Cancer epidemiology Cancer comprises several types of disease Cancer overall is one of the most common diseases worldwide Cancer affects all age groups, although for most types of cancer the risk rises progressively with age, as shown in the figure. There are over 100 types of cancer, mostly named for the primary site or area of the body in which they start, using the International Classification of Disease ICD- 11 codes 01/14/2025 Cancer: biology Source: National Institute of Health 01/14/2025 Cancer characteristics Source: Hallmarks, 2011 01/14/2025 Cancer types Source: Information from www.cancer.gov/about-cancer 01/14/2025 Cancer staging Stage and grade are important clinical determinants of treatment and prognosis. The stage describes the extent of the cancer using various measures: The site of the original tumour and its cell type The size of the tumour Whether any regional lymph nodes are involved Whether there are any metastases (further tumours around the body) Tumour grade, which describes how different the cancer cells/tissue are from normal tissue The stage is often described using the TNM system (Tumour, Nodes, Metastases): numbers from 0 (“carcinoma in situ”: where abnormal cells are present but have not spread into the tissue) to IV (where the cancer has spread to distant tissues or organs). Also, summary system group cancers into five main categories: in situ, localized, regional, distant, unknown. 01/14/2025 Cancer detection Clinical (physical) examination Histological confirmation – cell sample from tissue biopsy or blood sample Imaging: MRI CT scan Endoscopy Subject to specificity and sensitivity considerations Screening: systematic test of asymptomatic individuals depending on risk aiming to reduce mortality 01/14/2025 Cancer: measuring burden Burden can be expressed: prevalence, incidence and mortality. Incidence: number of new cases occurring in a specified population at risk over a specified time. Cancer incidence is not influenced by the treatment and survival -> informs the need for prevention within a country or region. Differences in cancer incidence across different populations, or changes within the same population over time can be driven by changes in risk factors but also variations in screening, diagnostic and registration practices. Mortality measures the average risk to the population of dying from a specific cancer. Data are usually collected from death certificates. depends on the case fatality rate (cancer type) and stage at diagnosis Prevalence is the proportion of existing cases in a population at a point in time. influenced by the number of new cases and the duration and severity of the cancer helps with the planning of the need for care within a population. Survival: probability of surviving for a certain amount of time after a cancer diagnosis 01/14/2025 Common cancers: trends Overall, survival is increasing with the improvement in diagnostics and treatment. Globally, the absolute number of cancer cases is likely to rise, with the burden greater in LMIC. Lung cancer: increasing in women, but overall the rate is lower than in men Breast cancer: the incidence has been rising over time in most of these example countries, although it has levelled off in more developed countries more recently Cervical cancer: around 8% of all cancer mortality in women in developing countries. Highest rates in LMIC where 85% of the global burden occurs. Pap smear decreased cancer rates significantly, due to treatment Stomach cancer: highest in developing countries in which more than 70% of cases occur. Half of the worldwide cases occur in Eastern Asia, mainly China. Colorectal cancer: the burden is predominantly in HIC (ca 55% of cases) potential due to diet. The trends over time vary greatly by country, but the incidence is generally decreasing in HIC and rising in LMIC. Prostate cancer: 70% of cases prostate cancer are found in HIC. There is a very large variation in incidence rates worldwide, potentially due to PSA testing Source: globocan.iarc.fr/Pages/fact_sheets_cancer.aspx 01/14/2025 Cancer: Prevention Cancer is preventable: it may have several concurrent causes, but we know many of the risk factors and many of them are avoidable. Prevention and control of cancer are central to public health. Behaviour modification, especially smoking cessation, vaccination and screening programmes, and improvements to diagnosis and treatment, can all have positive impacts, but these vary worldwide. There are large inequalities in outcomes between high and low middle income countries related to differences in access to prevention strategies, prompt diagnosis and effective treatments. 01/14/2025  Respiratory diseases: COPD and asthma 01/14/2025 Respiratory diseases: COPD and asthma Most prevalent RespD: Chronic obstructive pulmonary disease (COPD) and Asthma High burden in LMIC Result in considerable ill-health Share some clinical features and characterized by airway dysfunction involving airflow limitation Asthma has a range of phenotypes with different underlying pathogenic mechanisms; airflow limitation to be variable and reversible. However, when disease is poorly controlled over a long period of time, irreversible obstruction may develop. Has no cure but manageable. COPD: airflow limitation that is due to inflammation of the peripheral airways and/or lung alveoli due to exposure to noxious particles or gases. The airflow limitation in COPD is not fully reversible and generally progresses over time. COPD develops slowly over time and the symptoms often worsen. Spirometry and peak flow (PEF) meters are used to diagnose asthma by monitoring and measuring airflow limitation and are diagnostic tools that are used over a period of time to gain a full picture and understanding of a patient’s asthma status 01/14/2025 COPD and asthma: burden Asthma: most prevalent chronic respiratory disease in the world primarily more common in children, but becoming more common in adults Increasing in HIC and LMIC Substantial healthcare costs Direct: medication, visits by people with asthma to primary care and Emergency Departments, and hospitalizations Indirect: days lost from school and from work (for both those with asthma and their caregivers) and premature deaths Most famous study: the ISAAC study (International Study of Asthma and Allergies in Childhood) the first global study of allergies and asthma in children. was set up in 1991 and finished in December 2012. http://isaac.auckland.ac.nz 01/14/2025 Asthma prevalence The prevalence of asthma symptoms (defined as recent wheeze) varies widely between and within countries. Asthma is a disease of LMIC as well as HIC Asthma is more severe in LMIC Asthma is increasing in many countries Source: ISAAC Steering Committee, 1998 01/14/2025 http://isaac.auckland.ac.nz COPD: burden COPD is characterized by disability due to exacerbations when illness progress Breathlessness impacts daily functioning, affecting individuals’ ability to walk, wash and dress themselves and sleep. High healthcare costs: frequent hospitalisations, worsening of disease International studies: Burden of Obstructive Lung Disease (BOLD) - 4 North European and in 20 LMIC sites, participants > 40y.o., set in 1990 Latin American Project for the Investigation of Chronic Obstructive Lung Disease: (PLATINO) – five major metropolitan areas of Latin America, participants > 40y.o., set in 2002 01/14/2025 COPD prevalence BOLD: prevalence 5.7% - 23.0% in men, and f 4.2% - 20.7% in women (Burney et al, 2014) PLATINO: 11.0% -27.1% in men and 5.6% - 14.5% in women (Menezes et al, 2005); Prevalence of COPD increased markedly with age. Plot: Prevalence of COPD of GOLD stage 2 or higher (moderate COPD to very severe COPD. BOLD study (Buist et al, 2005) and from the PLATINO study (Menezes et al, 2005) 01/14/2025 Asthma: Genetic and environmental risk factors Several genes: affect one or more components of the causal mechanisms underlying asthma (such as atopic sensitization, airway inflammation or bronchial hyper- responsiveness). Interaction with environmental factors are more influential. Gender: Before the age of 12 years, the incidence and prevalence of asthma are consistently lower in females than in males. In contrast, the incidence of asthma after puberty is higher in women than in men. Age: asthma is more common in children but can develop at any stage in life. SES: lower SES increases exposure to risk factors that increase hospitalizations and morbidity – air pollution Exposure to tobacco smoke: established risk factor for developing asthma in children and in adults. Outdoor air pollution: exacerbate symptoms in individuals with pre-existing asthma Indoor air pollutants: kerosene, biomass fuels or coal; exacerbate asthma symptoms in those with asthma, but its association with incident asthma is less clear. Mould and damp: trigger asthma exacerbations 01/14/2025 COPD: Genetic and environmental risk factors People with genetic deficiency of the enzyme inhibitor alpha-1-antitrypsin are predisposed to develop COPD Gender: usually more common in men compared to women. But, incidence increased markedly in women. In HIC due to smoking. LMIC: exposure to indoor air pollution in the form of biomass fuel products used for cooking, heating and lighting. Age: usually after the age of 40 years, and incidence increases with age SES: Lower socioeconomic status is associated with increasing frequency of COPD Smoking: most important factor for COPD development Air pollution: exacerbates symptoms in individuals with existing COPD 01/14/2025 THANK YOU! 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