Epidemiology of chronic diseases in developing countries

Prof Isaac Quaye, UNAM SOM

Synopsis

• Definitions: epidemiology/chronic disease • Changing trends in disease epidemiology towards

non communicable • Core chronic diseases worldwide associated with

the most DALYs • Burden of disease global projections from

Institute of Health Metrics and Evaluation, Univ. of Washington

• Determinants of chronic diseases • Take home message

Epidemiology

• The study of epidemics (widespread increase of a disease in a community above an expected level at a particular time), with the aim of identifying the cause of a disease in order to reduce the attendant morbidity and mortality.

Chronic/non communicable diseases

• These are diseases that are NOT transmissible between persons.

• E.g. Cardiovascular diseases, cancer, chronic respiratory diseases, diabetes and hypertension

Infectious Chronic Diseases (ICDs)

• The issue of chronic diseases is now NOT limited to only the non communicable diseases but long term communicable diseases in particular HIV/AIDS and Tuberculosis.

• These fall under the category of Infectious Chronic diseases.

• Remember it is the “Chronicity” that impacts negatively on the patient, health service and health workforce.

• Interactions between ICDs and non communicable diseases present a formidable health condition for management.

Why are chronic diseases an issue today?

• There has been a gradual epidemiological transition in the burden of disease globally

• Initial transitions began from 1970 through 1980s in North America, Europe and Asia-Pacific countries

• In 1990, it was estimated that 34% of all deaths globally was due to communicable, neonatal and maternal deaths.

Winans B et al, 2011 (data for 2008)

Changes seen in 2010

• By 2010, communicable conditions accounted for only 25% of the 52.8 million deaths recorded in that year.

• The world has witnessed a shift from leading causes of premature death from communicable to non communicable diseases driven by AGE! This trend is ongoing!!!

Non communicable diseases causing the most harm

• In 2010, for the top 5 leading causes of death, 4 were non communicable:-

• 1. Ischemic heart disease • 2. Stroke • 3. Chronic obstructive pulmonary disease (COPD) • 4. • 5. Lung cancer • Of the leading causes of death Diabetes is the

FASTEST growing globally!!! • Hypertension is a leading risk factor for

Cardiovascular diseases

Source: Whiting DR et al, 2011

Burden of disease

• Concept of burden of disease uses a summary metric measured in DALYs (combined measure for morbidity, disability and mortality).

• DALYs: The number of healthy years of life lost to premature death and the number of years spent or lived with less than full health.

Burden of disease in DALYs

• If 1 DALY is represented as 1 lost year of health life then the burden of disease is a measure of the gap between the present health of a population and an ideal situation if all individuals lived to old age in full health.

Burden of disease in DALYs (2002) of the “Big four” chronic conditions

Disease Global DALYs Sub-saharan Africa DALYs

HIV/AIDS 84,457,784 63,962,104

Tuberculosis 34,735,908 9,266,350

Diabetes 16,194,381 1,114,952

Hypertension 7,646,994 586,467

ALL causes 1,490,125,643 361,376,478

Proportion of the four diseases among all causes

9.5% 20.7%

Chronic disease burden in selected developing and developed countries

Summary :leading causes of DALYs and % change from 1990 - 2010

Country Communicable, maternal, neonatal and nutrition disorders

Non communicable

Namibia 5 (HIV/AIDS, Malaria, TB : major ) 12 (diabetes, hypertension: major)

Angola 6 (Malaria, HIV/AIDS) 8 (l Back Pain, epilepsy)

Ghana 10 (malaria, HIV/AIDS) 12 (diabetes, IHD)

Mozambique 9 (HIV/AIDS, Schistosomiasis) 5 (Stroke, Low back pain)

South Africa 2 (HIV/AIDS, TB) 14 (Drugs, CKD, Diabetes)

Jamaica 1 (HIV/AIDS) 13 (Anxiety, Diabetes)

Brazil 0 16 (diabetes, osteoarthritis)

China 0 15 (IHD, lung cancer)

India 1 (HIV/AIDS) 9 (Diabetes, IHD)

Russia 2 (HIV/AIDS, TB) 12 (Cirrhosis, Drugs)

Italy 0 14 (Alzheimers, pancreatic cancer

USA 0 17 (Alzheimers, drug use)

Japan 1 (Lower respiratory infections) 16 (Alzheimers, pancreatic Ca)

What do these data present?

• That in sub-saharan Africa, there is a double burden of disease.

• There is a growing burden of chronic diseases (including ICDs)

• There is a growing burden of age associated diseases globally

Unfortunately in these regions it is the poor who have the highest risk of developing chronic conditions and the least able to cope with it.

Risk factors

Source: Egger G and Dixon J, 2014

Proximal/distal determinants for burden of disease in 2010

• For individuals aged 15-49, risk factors were: a. Alcohol use b. Tobacco smoking (including second hand

smoking) c. High blood pressure d. High BMI e. Diets low in fruits f. Drug use g. Particulate matter in households and ambient

environment

Take home message

• Individuals

• Community

• Governments

• Need educational and policy strategies to mitigate the rising burden of chronic diseases in particular diabetes and hypertension.