TB surveillance Philippe Glaziou Dubrovnik, May 2009
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
- 80 70 60 50 40 30 20 10 Case detection All sm+ 62% 62% in 2007 DOTS sm+ 100 80 60 40 20 0 76 69 61 56 53 47 W Pacific SE Asia Americas EMR Europe Africa case detection rate (%) 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007
90 86 82 78 74 70 Treatment success 84 81 80 82 82 82 83 79 79 77 77 Europe: 70%, Africa: 77%, Americas: 78% 84.7 85.3 2006 244,662 2.43 million 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005
Decline in global TB incidence -1%/yr AFR AMR EMR Incidence rate per 100,000/year 350 300 250 200 150 100 50 0 50 40 30 20 10 EUR 50 40 30 20 10 0 200 150 100 50 SEA 100 80 60 40 20 0 120 100 80 60 40 20 WPR 0 0 0 1990 1995 2000 2005 1990 1995 2000 2005 1990 1995 2000 2005
Trends in mortality (excl. HIV+)
Increase in estimated TB incidence in Eastern Europe (1990-2007) 80 70 60 50 Taux d'incidence pour 100000/an 0 50 100 150 200 1990 40 80 70 60 50 Taux d'incidence pour 100000/an 0 50 100 150 200 2007 40 0 50 100 150
Incidence rate per 100,000/year 100 90 80 70 60 Year Trends in GDP and TB incidence, Eastern Europe 1990 1995 2000 2005 50 1000 1500 2000 3000 5000 GDP per capita (US$, log scale)
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
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
MDR in new, 27 priority countries
MDR in re-tx, 27 priority countries
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)
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
Three estimates of incidence rate ratio
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
Increasing % of migrants among new TB cases in Western Europe Source: EuroTB 2007: http://ecdc.europa.eu/documents/pdf/eurotb_report.pdf
TB in migrants (Watkins et al, Epidemiol Infect 2002;129:623)
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
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
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
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)
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
Seek possible explanations for inflection points and changes in direction Severe economic crisis Improved health systems and control? Problems with reporting? Better reporting?
Changes in case notification (Mansoer et al, Bull WHO 2009; 87: 186)
Changes in HIV prevalence in Kenya (Mansoer et al, Bull WHO 2009; 87: 186)
Changes in case finding effort (Mansoer et al, Bull WHO 2009; 87: 186)
Trends in estimated incidence (Mansoer et al, Bull WHO 2009; 87: 186)
Does the decline in notifications in Albania reflect a decline in incidence?
Increased case finding effort Increased suspect investigations? Increased active case finding
Decline in notifications consistent with decline in incidence in Albania Decline in mortality Age patterns consistent with decline in incidence
Incidence currently estimated to mirror trends in notifications
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
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