CD4 and AIDS: For example in Cain et al. [34], hazard ratios (HRs) for AIDS or death were 1.37 (95% CI 1.20 to 1.57) and 1.20 (95% CI 1.05 to 1.38) for CD4 thresholds of 200 and 250 cells/μl versus 350 cells/μl.