However, we did further stratify analysis by CD4 count (Table 5), and if the adjusted risk ratio in those with advanced immunosuppression was a major driver, we would have likely seen a significant difference in this stratum (to note, the effect we see is in the opposite direction, i.e., in favour of Nix despite the higher frequency of advanced immunosuppression in the XDR-TB group). This evidence concerns the gene CD4 and tuberculosis.