CD4 and multidrug-resistant tuberculosis: The incremental cost-effectiveness ratios remained stable with wide variations in other parameters, including increasing the probability of major toxicity to 20%, increasing the probability of death from major toxicity to 20%, increasing the cost of active TB by 500%, tripling the prevalence of isoniazid-resistant TB to 48% (with prevalence of MDR-TB increased to 18%), ranging the overall incidence of TB from 5 to 10 cases/100 PY, and expanding the CD4 ART initiation to ≤350, cells/mm3.