Burden of disease:

Concepts and applications

Session Aims1. to introduce the concept “burden of disease”2. to examine patterns and trends in mortality

in Southern African settings3. to discuss and evaluate the concept of

“health transition”4. to introduce the concept of “priority setting”

and its relation to burden of disease studies5. to examine the implications of South African

mortality patterns for the provision of health care in the country.

Data to measure burden of disease

Industrialised versus developing settingsNational data

eg census, vital registration

Health facilitiesSurveys

eg household surveys: DHS

Sentinel site dataeg India, China, HDSS, verbal autopsy

Models

The disability-adjusted life year (DALY)

A single measure of disease burden

Expresses years of life lost due to premature death and years lived with a disability (ie years of healthy life lost due to poor health)

DALY: Values and methods

How “long” should people live?Is a year of healthy life now worth more than in 30 years’ time?Are we – all people – equal?How to compare years of life lost due to premature death, and years lived with disabilities of differing severities?

Trends in life expectancyAgincourt 1992-2003

52

66

60

72

50

55

60

65

70

75

1992-93 1994-95 1996-97 1998-99 2000-01 2002-03

Year

Lif

e e

xp

ecta

ncy

Female

Male

Relative increase in mortality, Agincourt 2002-2003 compared to baseline 1992-1993

0

1

2

3

4

5

6

7

0-4 '5-14 15-24 25-34 35-44 45-54 55-64 65-74 75-84

Age group

2002

-200

3 / 1

992-

1993

Female

Male

Trends in under-five mortality

0.0000.0100.0200.0300.0400.0500.0600.0700.0800.0900.100

1992-93 1994-95 1996-97 1998-99 2000-01 2002-03

Period

Death

rate

0-4

Female

Male

Trends in adult mortality Age 20-34

0.000

0.050

0.100

0.150

1992-93 1994-95 1996-97 1998-99 2000-01 2002-03

Period

Death

rate

20-3

4

Female

Male

Trends in cause specific mortality:Infectious & parasitic disease

0.0000

0.0005

0.0010

0.0015

0.0020

0.0025

1992-1994 1995-1997 1998-2000 2001-2003

Period

AS

DR

Diarrhoeal diseases

Acute respiratory infection

HIV/AIDS

Tuberculosis

Malaria

Other Infectious and parasitic diseases

Trends in adult mortality Age 50-64

0.000

0.100

0.200

0.300

0.400

0.500

1992-93 1994-95 1996-97 1998-99 2000-01 2002-03

Period

Death

rate

50-6

4

Female

Male

Trends in cause specific mortality:Women 50-64, broad categories

0.0000

0.0010

0.0020

0.0030

0.0040

0.0050

0.0060

0.0070

0.0080

0.0090

1992-1994 1995-1997 1998-2000 2001-2003

Period

AS

DR

Infectious and parasitic

Non-communicable

External

Ill defined or unknown

Age-standardised death rates, broad cause and broad health care categories, Agincourt 1992-2005

Top five causes of death, 50-64 years Agincourt 1992-2005

Top five causes of death, children and older adults, Agincourt 1992-2005

Prevalence of stroke survivors:South Africa, Tanzania, New Zealand

Comparison of age-standardised rates in three prevalence studies

0

100

200

300

400

500

600

700

800

900

1000

Male Female Total MalesNeeding Help

FemaleNeeding Help

Total NeedingHelp

Stroke Survivors

Pre

vale

nce

/ 10

0,00

0 A

ge-

Sta

nd

ard

ised

to

S

egi P

op

ula

tio

n

Auckland, New Zealand

Tanzania

Agincourt, South Africa

Sub-district services based on network of clinics staffed by primary care nurses with limited supportdrug supply irregularmedical supervision sporadic

Poor capacity to manage chronic illnessNo functional system secondary prevention

103 stroke survivors – only 1 on aspirin85 hypertensives – 8 on treatment; only 1 controlledGeneral pop ≥ 35 – 43% hypertension; 24% of these treated in past week; half with BP controlled

Missed diagnosesMajority of deaths with active TB had previously presented to clinic2/3 TB patients seen at a clinic self-referred to hospital

Care-seeking pluralistic – allopathic, traditional, faith-based most first visits to local clinics = pivotal role

Managing chronic NCDs in Agincourt

Age-standardised death rates by health care

categories, Agincourt sub-district 1992-2005

PHC in Practice: Integrating HAART & chronic NCD care

Age and sex standardized death rates, by social strata, Agincourt 1992-2000

0.000

0.001

0.002

0.003

0.004

0.005

0.006

Highest Higher Medium Lower Lowest

Strata

ASD

R

Age-specific death rates by nationality of household head

Age-specific death rates by nationality of household head, Agincourt, 2000-2001

0

0.0002

0.0004

0.0006

0.0008

0.001

0.0012

0.0014

0.0016

0-1 1-2 2-3 3-4 4-5

Age in years

Ag

e s

pecif

ic d

eath

rate

South African

Mozambican

Reasons given for non-consultation: no money, ineffective care

0

10

20

30

40

50

60

70

80

90

100

Reasons for not takingtreatment action

Other non-access barriers

Feeling better

Illness not serious enough

Other access barriers (Too far,nobody to go with patient, no time)

Health system access barriers (Healthcare can do nothing, drugs don'twork, no drugs at clinic)

No money

25%

18%

26%

7%

Household survey dataNo money

Implications of mortality patterns for health system

Shift orientation of service provision: chronic, long-term care as well as acute, episodic care

Tackle (prevent/control) increasing burden of non-communicable disease and riskStrengthen HIV/AIDS (and TB) prevention, treatment and careSimultaneously maintain and improve on gains in child and maternal health

• Strengthen primary care provision + referral system

• Address differential access to care

Epidemiological Transition

Epidemiologic transition theory: 3 stagesPestilence and famineReceding pandemicsMan-made or degenerative disease

CritiqueNot same direction: reversals in mortality “counter transition”Not sequential: stages may overlap, co-existence different diseases “prolonged/protracted transition”Too general: insufficient attention to subgroup differences “epidemiologic polarisation”

Rethinking epidemiologic transition: mortality patterns in rural South Africa

Counter transitionMortality increasing in children and young adults

Protracted or prolonged transitionSimultaneous emergence of HIV/AIDS together with increasing non-communicable disease

Epidemiologic polarisationPoorest experience highest burden of mortality

Why is burden of disease information necessary?

“priority setting” and its relation to burden of diseaseProgramme planningProgramme evaluation