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Open Access Research article

Estimating the magnitude and direction of bias in tuberculosis drug resistance surveys conducted only in the public sector: a simulation study

Ted Cohen12*, Bethany L Hedt3 and Marcello Pagano3

Author Affiliations

1 Division of Global Health Equity, Brigham and Women's Hospital, 641 Huntington Avenue, Boston, 02115, USA

2 Department of Epidemiology, Harvard School of Public Health, 677 Huntington Avenue, Boston, 02115, USA

3 Department of Biostatistics, Harvard School of Public Health, 677 Huntington Avenue, Boston, 02115, USA

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BMC Public Health 2010, 10:355  doi:10.1186/1471-2458-10-355

Published: 21 June 2010

Additional files

Additional file 1:

Bias in retreatment cases when there is not necessarily equal prevalence of MDR among new cases presenting to public and private sectors. Percent bias in retreatment cases as a function of the relative risk of acquired drug resistance and relative risk of failure in the private sector. Blue represents parameter space in which public sector surveys overestimate total resistance and red represents parameter space in which public sector surveys underestimate total resistance; more saturated colors indicate greater bias. The values on the lines indicate percent bias. Results present values at equilibrium with a = 0.1; fS = 0.1; fR = 0.25; l = 0.2; q = 0.6; rN = 0.85; rP = 0.5. The panels represent four alternative possibilities for the likelihood and preference for new MDR cases to present in the public or private sector. This figure should be compared with Figure 3 of the main text.

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Additional file 2:

Bias in retreatment cases under the assumption that the probability of acquisition of resistance is lower in the private sector. Percent bias in retreatment cases as a function of the relative risk of acquired drug resistance and relative risk of failure in the private sector when acquired resistance is more common for patients treated in the public sector. The values on the lines indicate percent bias. Results present values at equilibrium with aN = 0.1; aP allowed to vary; fSN = 0.1; fSP allowed to vary; fRN = 0.25; fRP allowed to vary; l = 0.2; q = 0.6; xR = 0.2; xS = 0.2. The panels represent four different scenarios of patient preference for retreatment in public or private sector. In each of these scenarios, public sector surveys overestimate total resistance. This figure should be compared with Figure 3 of the main text.

Format: PDF Size: 2.9MB Download file

This file can be viewed with: Adobe Acrobat Reader

Open Data