IP10 as a diagnostic marker for childhood tuberculosis in a Tanzanian population

Intro A main challenge in childhood TB management is the lack of good diagnostic tools. IP-10 is a novel marker for latent tuberculosis (TB), but very few studies have examined the use of IP-10 in childhood TB. Aims To compare the performance of the Quantiferon test (QFT) and IP-10 for the diagnosis of TB in Tanzanian children Methods 207 TB suspected children (0-15 years) and 102 adults with confirmed TB were included. QFT tests were analyzed locally and IP-10 was measured using ELISA. The children were divided in to three risk groups using clinical parameters, CXR, microscopy and culture: Confirmed/highly probable TB (probTB, n=33), possible TB (possTB, n=84) and Not TB (notTB, n=90). Results In children the positivity rate was low in all groups for both tests. View this table: Table 1 IP-10 positivity rate was associated with TB risk groups (p=0.02), QFT was not (p= 0.12). The agreement between IP-10 and QFT was 70%, discordance was mainly found in the possTB and notTB groups, combining tests did not increase test sens. For both tests indet. outcome was not associated with HIV status, young age or malnutrition. In adults the sens. was 80% for both tests; and the indet. rate was 11% for IP-10 and 6% for the QFT (agree. 83%, k=0.5, p<0.0001). Discussion In the children both tests had poor performance with low positivity rate and high indeterminate rate; this was not explained by risk factors for poor test performance. In adults the QFT and IP-10 test performance was in line with other studies. Our findings could be explained by group heterogeneity and severity of illness.