TB serodiagnostic tests have been found to be inaccurate and unreliable, leading the WHO to issue a strong recommendation against the use of serological tests for the diagnosis of active TB (http://apps.who.int/iris/bitstream/10665/44652/1/9789241502054_eng.pdf).
In the 2011 policy statement, the WHO encouraged further research in this area, specifically prospective, blinded studies investigating the performance of serodiagnostics for representative populations with presumptive TB.
In our recently published study (https://doi.org/10.1093/cid/cix023), we collected blood samples from 755 adults with presumptive pulmonary TB and measured IgG antibody responses to >100 antigens. Using WHO TPP criteria for a TB detection and triage test, we evaluated single antigen performance as well as models of all possible 3-antigen combinations and models with >3 antigens.
TB detection test results: 35% sensitivity at 90% specificity (TPP minimal target: 65% sensitivity at 98% specificity)
TB triage test results: 34% specificity at 85% sensitivity (TPP minimal target: 70% specificity at 90% specificity)
These results suggest that a conventional antigen-based IgG detection test is unlikely to meet TPP requirements in symptomatic patients. This is in concordance with several systematic reviews and meta-analyses.
(a) Is this the end of the story, or is there still a role for antibody detection for the detection of active TB?
(b) Is it worth considering antibody detection in combination with detection of other host markers (e.g. cytokines)?
(c) What is the relevance of IgG properties such as FcR-functional profiles (see https://www.ncbi.nlm.nih.gov/pubmed/27667685)?
(d) Could antibody detection be relevant for other target conditions (e.g. progression from latent to active TB)?
(e) Is anyone still using commercial tests based on antibody detection in practice and what is the rational?
Link leads to: https://doi.org/10.1093/cid/cix023