Understanding the impact of disease

control

Berlin April 2009

Questions Routine OR Surveys Research

Size of Notifications Private sect. Prevalence Active CFthe Cure rate Vital Reg. MDRproblem Deaths

Direction Notifications Sent. sites Trends Modellingof change Tr. outcomes MDR

Reasons HIV; MDR; Risk factors Gender Duration dis.for change Diagnostics Social issues Urbanization

Access PPM

Impact of Notifications Diagnosis Prevalence DOTSControl Cure rate Drug supply Incidence IPT

Deaths Qual. control

Global report S. Africa MDR S. Korea

Morocco China Europe World

Malawi India Morocco Gold mines

Peru Chennai S. Korea Czech

Highest TB rates per capita are in Africa

25 to 49

50 to 99

100 to 299

< 10

10 to 24

300 or more

No Estimate

per 100 000 population

The boundaries and names shown and the designations used on this map do not imply the expression of any opinion whatsoever on the part of the World Health Organization concerning the legal status of any country, territory, city or area or of its authorities, or concerning the delimitation of its frontiers or

boundaries. Dotted lines on maps represent approximate border lines for which there may not yet be full agreement.© WHO 2002

Size/RoutineBack

Size/OR

Estimating case detection rates from vital registration data. Red: Statistics South Africa. Blue: TB programme. Estimated fractional errors.

2001

TB deaths (k) 50.9 a

All deaths (k) 451.9 bUnknown causes (k) 56.2 cDeaths due to HIV 9.2 dCompleteness of reporting (%) 90.0 eProportion of HIV deaths due to TB 15.0 fEstimated TB deaths (k) 66.1 g = [a+ca/(b-c)+df]/eCFR negative (%) 17.2 hCFR positive (%) 37.0 iProportion of cases HIV positive (%) 41.9 jCFR (%) 25.5 k = h(1-j)+ijNotifications (k) 197.0 lNotified TB deaths (k) 50.2 m = k*l/100CDR (%) 76.0 m/g

TB deaths = Incidence ×××× Case fatality rate

Back

Add a proportion of ‘unknown’Add a proportion of HIV deathsAllow for completeness of reporting

0.6

0.4

0.2

0.0AFR AMR EMR EUR EUR SEA WPR AFR AMR EMR EUR EUR SEA WPR

E W E W

Isoniazid resistance MDR resistance

Pro

port

ion o

f T

B c

ases

Anti-tuberculosis drug resistance in the world: Fourth Global Report. Geneva: World Health Organization; 2008.

BackSize/Surveys

0

100

200

300

1960 1970 1980 1990

SS

+ T

B incid

ence/1

00k

ARTI×50

Civil servants

South KoreaSize/Research 1

Fwd

10

100

1,000

10,000

100,000

1,000,000

0.01 0.1 1 10 100

1

2

4

8

16

32

64

Percent positive

Sam

ple

siz

e

Precision (%)

Calculating sample sizesSize/Research 2

Back

Direction/Routine Back

Notifications in Morocco

Proportion of cases > 15 years old

DOTS reduces prevalence of culture+

TB by 37% in less than a decade in China

0

50

100

150

200

250

1990 2000

Pre

va

len

ce

cu

ltu

re+

TB

/10

0,0

00

DOTSOther

Direction/ORBack

China Tuberculosis Control Collaboration. The effect of tuberculosis control in China. Lancet. 2004;364:417–22.

Fwd

Direction/Surveys

Fwd

Direction/Surveys

-0.5

0.0

0.5

1.0

1.5

2.0

Russ

iaH

ong Kong

West

ern E

urope

Lithuan

ia

Latvia

Estonia

Unite

d Sta

tes

Cen

tral

Euro

peG

erm

any

Unite

d Kin

gdom

Ca

se

re

pro

du

cti

on

nu

mb

er INH sensitive

INH resistant

Multidrug resistant

severe epidemic

benign epidemic

In 9/10 sites, all TB strains are on a slow path

to elimination Is transmission of MDR strains self-sustaining?

Fitting simple models suggests not… Back

Direction/Surveys

Treatment of latent infections/yr

Treatment of TB cases/yr

New

TB

cases p

er

mill

ion in 2

050

Dye C, Williams BG. Eliminating human tuberculosis in the twenty-first century. J R Soc Interface. 2007.

BackDirection/Research

Treat cases

Treat latent

Treat both

1000

0.000.05

0.10

0

32

1

100

10

1

0.1

0.00

0.02

0.04

0.06

0.08

0.10

0.12

0.14

0.16

1980 1990 2000 2010 2020

Year

0.00

0.01

0.02

HIV

pre

va

len

ce

HIV

incid

ence a

nd m

ort

alit

y0

50

100

150

200

250

1980 1990 2000 2010 2020

YearT

B incid

ence

/100

k/y

r

Prevalence of HIV in adults fitted to an

SI model.Predicted TB notification rate for TB

Adult prevalence of HIV and SS+ notification rate for TB

in Malawi

Data from UNAIDS (HIV) and WHO (TB)

Reasons/RoutineBack

Smoking and TB in Chennai

27k deaths and 16k controls, 1994-1997. 2k TB deaths

Gajalakshmi, V., Peto, R., et al. Smoking and mortality from tuberculosis and other diseases in India:

retrospective study of 43000 adult male deaths and 35000 controls Lancet (2003) 362 507–515.

Smoker Non-smoker Odds

TB deaths 1454 386 3.76

Controls 6430 10058 0.64

OR = 5.9 (4.5)

0.66 (0.61)RR -1

PAF = ×F =RR

F = 0.79

60% of all TB deaths among men in Chennai are attributable to smoking

Reasons/ORBack

64

44 32

20

1

2

3

4

5

6

0Urban Rural Urban Rural

Men Women

Declin

e in S

S+

TB

cases (

%/y

r)

Rate of decline in reported SS+ TB cases per year

in men and women in urban and rural districts of

Morocco. Inset numbers: rate/100k in each group.

BackReasons/Surveys

9.4

1.11.11.0

5.9

2.2

0

2

4

6

8

10

1991-1994 1995-1997 1998-1999

Annual incidence

(%) .

HIV- HIV+

TB incidence among gold miners in SADDR

Reasons/Research 1Fwd

Smear positive disease in

South African gold miners

Incidence (%/yr) Prevalence (%) Dis.Duration (yr)

HIV- 0.48 0.55 1.15

HIV+ 2.87 0.44 0.15

Ratio 6.01 0.80 0.13

Corbett et al. 2003

Reasons/Research 2Back

0

50

100

150

200

250

1980 1985 1990 1995 2000 2005

0

500

1000

1500

2000

2500

Pu

lmon

ary

TB

cases/1

00k/y

ear

Slid

es e

xa

min

ed (

k/y

r)

Suarez, P. G. et al. The dynamics of tuberculosis in response to 10 years of intensive control effort in Peru. J Inf. Dis 184, 473-8 (2001)

Decliningnotification rate

Impact of DOTS in Peru

200

100

0

2

1

0 Slid

es e

xam

ined (

M/y

r)

1980 1990 2000

Impact/RoutineBack

Impact/OR

"Model DOTS Project" reduces TB prevalence in

south Indiasource: TRC Chennai

0

1000

2000

68-

70

71-

73

73-

75

76-

78

79-

81

81-

83

84-

86

99-

01

01-

03

Year

Pre

va

len

ce

/10

0K Male C+

Male S+

Female C+

Female S+

fall ~10%/yr in

MDP

Back

P = a e-0.0797t

0

100

200

300

400

500

600

700

800

900

1960 1965 1970 1975 1980 1985 1990 1995

Pre

va

len

ce

SS

+ T

B/1

00

kSouth KoreaImpact/Surveys

Back

0

50

100

1960 1961 1962 1963 1964

Men SS+ Men SS-

Women SS+ Women SS-

Year

Case

s

Decline in prevalence

Kolin, Czechoslovakia

Men: 20% ± 10%/yr

Women: 26% ± 21%

China

Impact/ResearchBack

The last word…

We must eradicate tuberculosis, and we must do it now, … All available resources must be used. Chemotherapy, computers, prophylaxis and prevention, case finding and kindness can be blended in a properly constructed epidemiological model which will tell us exactly where we are going and how fast.

Davies, J.C.A. The Eradication of Tuberculosis in Rhodesia DPH, London School of Hygiene and Tropical Medicine, 1966

Back

Decline in TB, Alaska 1950-73

-2

-1

0

1

2

3

4

5

6

1950 1955 1960 1965 1970 1975

Inc

ide

nc

e o

r d

ea

th r

ate

/10

K/y

ea

r

source: Grzybowski Tubercle 1976

deaths 30%/yr

t1/2 = 2.3 yr

cases 13%/yr

t1/2 = 5 yr

Direction/SurveysBack