Association of Age at Antiretroviral Therapy Initiation with CD4+: CD8+ Ratio Recovery among Virally Suppressed People with HIV

Objective: To investigate the association of age at antiretroviral therapy (ART) initiation with CD4(+) : CD8(+) T-cell ratio in virally suppressed people with HIV on long-term ART, and to characterize potential CD4(+) : CD8(+) ratio recovery in this population by age. Design: A longitudinal study of people attending an HIV clinic at the Royal Free Hospital NHS Trust, London, who initiated ART between 2001 and 2015, and achieved and maintained HIV-1 viral suppression (viral load <1,000 copies/ml). The association of age group at ART initiation with CD4(+) : CD8(+) ratio at 5 and 10 years was assessed. Methods: Multivariable linear regression was used to investigate the relationship between age at ART initiation and log CD4(+) : CD8(+) ratio, adjusting for demographic factors (gender/HIV transmission route, ethnicity), baseline CD4(+) count and calendar year. Results: The sample included 1859 people aged 20-78 (75% men, 56% white ethnicity). Overall, median CD4(+) : CD8(+) T-cell ratio increased from 0.24 at baseline to 0.77 at year 5 and 0.88 at year 10. Ratios increased among all age groups in unadjusted and adjusted models but increased less among older ages (baseline ages 60-69 and 70-79). Median ratios at year 5 were 0.85, 0.80, 0.72, 0.76, 0.6, and 0.44, respectively, among people aged 20-29, 30-39, 40-49, 50-59, 60-69 and 70-79 years at baseline. Conclusion: In a virally suppressed London population, age had a substantial impact on CD4(+) : CD8(+) ratio recovery, especially for those starting ART after age 60 years. Results may indicate the level of CD4(+) : CD8(+) ratio recovery possible in an HIV-positive, virally suppressed, aging population.