Understanding the impact of disease control Berlin April 2009 · Dye C, Williams BG. Eliminating...
Transcript of Understanding the impact of disease control Berlin April 2009 · Dye C, Williams BG. Eliminating...
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