Fig 1.
The Flow diagram shows children referred to the TB dispensary.
Eligible for the final analysis were 2710 children and reasons for exclusion and numbers are displayed. Children were divided into TB disease, immune correlate of TB infection and TB non-infected. As immune correlate of TB infection, we defined for the purpose of this study the presence of at least one TST with induration of ≥10 mm and/or DT with induration of any size. Since this definition differs from the one used for TB infection and indications for TB treatment in clinical practice in the Russian Federation only a proportion of the children was started on treatment.
Table 1.
Characteristics of the study population in the following groups: TB-uninfected, immune correlate of TB infection with and without treatment and TB disease.
Fig 2.
Venn diagram using exact Euler calculation showing positive test results for TST, DT and initiation of treatment in children with immune correlate of TB infection.
TST positivity was defined as with induration ≥10 mm and DT positivity as any induration. The area of the ellipses is proportional to the number of cases. As immune correlate of TB infection, we defined for the purpose of this study the presence of at least one TST with induration of ≥10 mm and/or DT with induration of any size. Since this definition differs from the one used for TB infection and indications for TB treatment in clinical practice in the Russian Federation only a proportion of the children was started on treatment.
Fig 3.
Final diagnosis of children referred to the TB dispensary by reason for referral.
Among children referred for an abnormal routine annual screening and following a contact with a TB case the proportion of immune correlate of TB infection was highest with 62.3% and 16.2%, respectively (see also S1 Table).
Fig 4.
DT and TST positivity in children who had contact to an TB index case, stratified by the smear results of the contact.
Children exposed to a smear positive index case were more likely to have a positive DT and TST (in red) compared to children exposed to smear negative or unconfirmed contacts.