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Review of Wednesday 5 th 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.
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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 3Prevalence 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 8ARTI & 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!!!