TB surveillance. Philippe Glaziou Dubrovnik, May 2009

Transcription

1 TB surveillance Philippe Glaziou Dubrovnik, May 2009

2 What are the global TB targets? Outcome targets (World Health Assembly, STB Partnership) Case detection ratio > 70% Treatment success > 85% 2015 Impact targets (MDGs, STB Partnership) Halt and reverse incidence (MDG 6) Halve prevalence and mortality levels of 1990

3 Case detection All sm+ 62% 62% in 2007 DOTS sm W Pacific SE Asia Americas EMR Europe Africa case detection rate (%)

4 Treatment success Europe: 70%, Africa: 77%, Americas: 78% , million

5 Decline in global TB incidence -1%/yr AFR AMR EMR Incidence rate per 100,000/year EUR SEA WPR

6 Trends in mortality (excl. HIV+)

7 Increase in estimated TB incidence in Eastern Europe ( ) Taux d'incidence pour /an Taux d'incidence pour /an

8 Incidence rate per 100,000/year Year Trends in GDP and TB incidence, Eastern Europe GDP per capita (US$, log scale)

9 Multidrug Resistant TB Direct measurements in 113 countries (new cases), of which 102 countries also have measurements on retreatment cases with π = Pr(MDR new), c = incident cases (new or retreatment), r = reported retreatment episodes and n = notified new cases

10 MDR-TB (cont) In countries with no direct measurement, p predicted from models with indirect predictors such as Gross National Income, retreatment ratio r/n; % HIV in TB Model predictions should be replaced with measurements from quality surveillance data

11 MDR in new, 27 priority countries

12 MDR in re-tx, 27 priority countries

13 Increase in HIV testing coverage National surveys of HIV in TB 7 countries (up from 2 last year) HIV sentinel surveillance systems 8 countries Provider Initiated HIV Testing and Counselling (where tested/new > 50%) 49 countries (up from 13 last year)

14 Measurements of TB/HIV incidence Empirical measurements from 64 countries (7 national surveys, 8 sentinel surveillance, 49 providerinitiated HIV testing data with > 50% of new TB cases tested for HIV) Incidence rate ratio (TB in HIV+ / TB in HIV-) modelled HIV in TB predicted from UNAIDS estimates in the general population

15 Three estimates of incidence rate ratio

16 TB/HIV summary 1.4mincident TB infected with HIV (15% of 9.3m) 63% of total TB/HIV estimated indirectly (104 countries) through the IRR method: need to scale up TB/HIV surveillance Impact of ART on IRR

17 Increasing % of migrants among new TB cases in Western Europe Source: EuroTB 2007:

18 TB in migrants (Watkins et al, Epidemiol Infect 2002;129:623)

19 WHO Task Force on TB Impact Measurement Mandate assessment of whether the 2015 impact targets are achieved monitor progress towards impact targets strengthen national capacity in monitoring and evaluation Strategic approach Strengthened national surveillance "certification" of notification data Development of vital registration systems Periodic updating of methods for producing estimates from surveillance and survey data Prevalence surveys in 21 global focus countries

20 Policy Package General TB incidence 1. Improve routine surveillance so that notified TB cases record all incident TB cases, VR data record all TB deaths 2. Strengthen capacity in M & E 3. Periodic review and update of estimation methods 4. reliability and coverage of TB notification data 5. Standard framework for systematic analysis of TB notification data 6. Certification of TB notification data 7. Cross-validate incidence estimates using TB mortality data from VR systems

21 Policy Package (cont) TB prevalence TB mortality Impact evaluation 8. Prevalence surveys in 21 global focus countries 9. Indirect estimates of TB prevalence using estimates of TB incidence and duration 10. Strengthening VR systems, TB deaths reliably recorded 11. Sample VR as interim solution 12. Indirect estimates based on estimates of TB incidence and case fatality rate for countries without reliable national or sample VR 13. Periodic studies to evaluate impact of TB control on TB incidence, prevalence and mortality

22 Countries where nationwide surveys of disease prevalence are recommended Surveys will also produce evidence about where and why cases are being missed 12/21 global focus countries in Africa 21 global focus countries 36 additional countries that met basic criteria See: WHO Global Task Force on TB Impact Measurement, December 2007 meeting report; WHO Policy Paper (forthcoming)

23 Standard framework: a prototype Data Quality Changes over time Trends in Incidence Incidence Reports complete No dups, no misclassified Data internally consistent Data externally consistent Measure time-changes in notifications Assess changes in case-finding Assess changes in TB determinants Trends in notifications reflect trends in incidence capture re-capture onion model cross-validation notifications incidence IMPROVE surveillance system Entry point to evaluate IMPACT UPDATED estimates CERTIFIED

24 Seek possible explanations for inflection points and changes in direction Severe economic crisis Improved health systems and control? Problems with reporting? Better reporting?

25 Changes in case notification (Mansoer et al, Bull WHO 2009; 87: 186)

26 Changes in HIV prevalence in Kenya (Mansoer et al, Bull WHO 2009; 87: 186)

27 Changes in case finding effort (Mansoer et al, Bull WHO 2009; 87: 186)

28 Trends in estimated incidence (Mansoer et al, Bull WHO 2009; 87: 186)

29 Does the decline in notifications in Albania reflect a decline in incidence?

30 Increased case finding effort Increased suspect investigations? Increased active case finding

31 Decline in notifications consistent with decline in incidence in Albania Decline in mortality Age patterns consistent with decline in incidence

32 Incidence currently estimated to mirror trends in notifications

33 Methods to update estimates of disease burden Review started in June 2008, jointly by KNCV and WHO Global Burden of Diseases update: estimates for 1990 and 2005 Updated methods to be reviewed by the Task Force in October 2009 Use of VR data

34 In conclusion Strong surveillance system based on notifications in Europe Need to strengthen surveillance of drug resistance and TB/HIV Need for robust and widely endorsed estimates of incidence, prevalence and mortality Comprehensive WHO policy package about to be published