Contours of cases averted for different round efficiencies for HIV-infected and HIV-uninfected TB cases.

<p>These contours are the cases averted (as a percentage of the largest number averted) by yearly rounds with different efficiencies at finding HIV-infected and HIV-uninfected TB. Other parameters are the defaults of <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0029130#pone-0029130-t001" target="_blank">Table 1</a>.</p

Cumulative cases found by both active and passive systems.

<p>Solid lines for HIV-uninfected TB, dashed lines for HIV-infected TB, and dotted lines for cumulative cases without interventions beginning at year 10. Both panels are for the default parameters of <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0029130#pone-0029130-t001" target="_blank">Table 1</a>, with . Panel A has , whereas panel B has case detection rates . Fewer HIV-infected TB cases are found in total under the intervention in both panels. Fewer cases of HIV-uninfected TB are found in panel A, and more cases of HIV-uninfected TB in panel B.</p

Modelling prevalence given incidence.

<p>An active TB case develops at , and remains active until . The probability that this case avoids death, self-cure or detection by routine services to remain active at is . In the presence of -periodic active case-finding (vertical lines) beginning at time , the case must also avoid detection by intersection with case-finding rounds (marked as filled circles), which occurs with probability .</p

Proportion of cases averted for different round efficiencies and cases found at different periods.

<p>Panel A shows the total proportion of cases over a 10 year time frame averted by yearly case-finding rounds of different efficiency. Parameters are the default of <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0029130#pone-0029130-t001" target="_blank">Table 1</a>, but with different initial proportions recent . Panel B compares for rounds of different efficiency, , the influence of round frequency on the number of HIV-infected and HIV-uninfected TB cases found by the active route (normalized by the number of cases actively found at the shortest round period considered).</p

Model parameters.

†<p>Default example: changes in parameter investigated.</p><p>*Only affects conclusions about numbers of cases found.</p

Cases found and averted for different round efficiencies, periods and initial case detection rates.

<p>Results from numerical model experiments plotted against the product of round efficiency and the number of rounds during the 10 year intervention period, in a population of 100,000. Panels A and B are the total HIV-infected and HIV-uninfected TB cases averted, respectively. Panels C and D are the total HIV-infected and HIV-uninfected TB cases found by both routine and active routes, respectively. Panels C and D have points colored by initial case detection rates; initial case detection rates do not affect cases averted. Realistic levels of achievement would be below , or a perfectly efficient round once a year. All panels have parameters other than those varied set to the default parameters of <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0029130#pone-0029130-t001" target="_blank">Table 1</a>, although the overall level of incidence only affects the scales here. The round efficiencies, , were chosen to vary from 10% to 90% in increments of 10%; and 28 values of the period were investigated, chosen so that the number of rounds over the 10 years was an integer in the range 2 to 49.</p

Approximate regions with fewer cases in total over the 10 years of the intervention.

<p>The red, vertically hatched regions are the critical initial case detection rates for HIV-infected TB, above which fewer HIV-infected TB cases are found by the combination of routine and active routes over 10 years. The green, horizontally hatched regions are the critical initial case detection rates for HIV-uninfected TB, above which fewer HIV-uninfected TB cases are found by the combination of routine and active routes over 10 years. The grey, diagonally hatched region indicates fewer total cases regardless of HIV-status. The default parameters of <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0029130#pone-0029130-t001" target="_blank">Table 1</a> are used but with . The HIV prevalence in incident TB affects the slope of the diagonal line, but the main factor that changes this picture is the initial proportion recent: results for and are indicated by dashed and dotted lines, respectively.</p

Approximate regions where intervention is cost-saving over 10 years.

<p>If the reduction in case load over the intervention is large enough to mean the treatments save (more than) pay for the case-finding rounds then the intervention saves the health system money. This happens for a high enough initial burden, and for a low enough cost per round relative to the cost of treatment (hatched regions). We have factored out efficiency to allow for approximate comparison between screening strategies of different efficiency. The HIV prevalence in incident TB, , makes some difference; but the most influential factors in determining these regions are the initial case detection rates () and the initial proportion recent ().</p

Global map showing countries in which prevalence surveys have been conducted.

<p>Yellow indicates low- and middle-income countries for which sex-disaggregated data are available from at least one prevalence survey (<i>n =</i> 24). Red indicates low- and middle-income countries in which at least one prevalence survey has been conducted but sex-disaggregated data are not available (<i>n =</i> 4). Dark gray indicates low- and middle-income countries where no prevalence survey has been identified (<i>n =</i> 107). Labels show the total number of surveys identified within each country for which at least one prevalence survey was identified (<i>n =</i> 88).</p

Random-effects weighted male-to-female prevalence ratios for bacteriologically positive TB by age group (<i>n =</i> 19).

<p>Analysis includes surveys that report the number of individuals screened and the number of bacteriologically positive TB cases by sex and age. Horizontal axis shows age groups in years. Vertical axis shows random-effects weighted M:F ratios in prevalence of bacteriologically positive TB per 100,000 individuals with 95% confidence intervals.</p