Review of Wednesday 5th May Workshop on Surveillance and Epidemiology of Tuberculosis in the Western Pacific Region 6 May 2004, Manila Marleen Vree

Overview Wednesday Lectures on direct and indirect estimates of TB burden Exercises Discussions Started to work on own data

Direct estimates of TB burden Prevalence of infection Difficulties to determine which method you use to calculate prevalence of infection Formula to calculate Annual Risk of Tuberculosis Infection Underlying assumptions were discussed

Incidence of disease From ARTI to Incidence using Styblo’s rule 1% Annual Risk of infection: SS+ incidence 50 / 100.000/ yr. Situation: stable epidemic no control program no HIV Is this the case in your country?

Incidence of disease Incidence TB = prevalence/ duration Prevalence survey & delay studies = Notifications/ proportion detected = deaths/ proportion cases dying

HIV-epidemic Influence of HIV on TB notification HIV prevalence among TB cases and prevalence of HIV in adults: RR of 5 6 years delay Where is your country in the HIV epidemic? (only in risk groups, low/ high prevalence in general population) Can you predict what your notification rates will look like in 6 years?

Exercise 3 Prevalence of infection  ARTI DO Calculated: ARTI by gender and age Plotted: ARTI – mean calendar year Draw lines: exponential and linear UNDERSTAND METHODS Why take mean calendar year? Why transformation of data? (LN) INTERPRETATION Was there a decline in ARTI? Why was there a difference between age?

Exercise 8 ARTI & Prevalence of disease DO Calculated: ARTI by two methods (10 mm cut-off, 17 mm ‘mirror’) Rate of decline in prevalence of disease UNDERSTAND METHODS What is the difference between 10 mm cut-off and 17 mm ‘mirror’? From so many numbers in a table: why do you choose the one you choose? INTERPRETATION Notice how the method influence the rate of decline of ARTI From prevalence of tuberculosis infection to ARTI to incidence of disease compare with prevalence of disease this produces: DISCUSSION

Working with data: understand which data you work on Give title to your graph: Men/ women Age group Name the axis: Prevalence/ incidence/ notification? ARTI or LN (ARTI) After calculating: is your figure plausible? For example: incidence: 5 per 10000: Did you forgot to type 0 in formula? Is your figure plausible in relation to other figures?

Your data More insight in what others have estimated for your country and understanding of assumptions What were the assumptions? Are these assumptions true in your country? Or have changes taken place (recently)? Do you have detailed information which you have not used yet? Get more insight in your own data and the situation in your country.

Discuss Yesterday a lot of discussions Bring information together: Knowledge about TB control program & health care system in a country Knowledge about (quality of) reporting and reporting system Knowledge about epidemiology Knowledge about … (similar situation in other countries) Clear eye for … (fresh look) So… try & discuss!

Analysis of own data Trend in notification rates/ deaths Best estimates in incidence, prevalence and deaths Best estimates of case detection SUCCESS!!!