In sensitivity analyses, we found similar survival differences across different CD4 testing frequencies when switching criteria were varied to exclude a switch following extrapulmonary tuberculosis, to include a switch at all non-Candida WHO 4 events irrespective of current CD4 count, or to depend on event history lagged by 4 weeks (Web Table 2), and irrespective of the use of cotrimoxazole during weeks 48–72 of ART (Web Appendix 3 (including Web Table 3)). This evidence concerns the gene CD4 and extrapulmonary tuberculosis.