Association between CD4 count, CD4/CD8 ratio, and fragility fractures in people living with HIV: a retrospective cohort study in China.

Background: People living with HIV (PLHIV) often exhibit reduced CD4+ T cell counts and altered CD4/CD8 ratios, but their impact on fragility fractures remains underexplored. This study investigated the association between CD4 count, CD4/CD8 ratio, and fragility fractures in PLHIV in China.

Methods: A retrospective cohort study was conducted on PLHIV treated at Beijing Ditan Hospital from January 2011 to September 2023. Data on demographics, clinical status, and bone mineral density were collected. Fragility fractures were identified through medical records. Multivariate Cox regression was used to assess the relationship between CD4 count, CD4/CD8 ratio, and fracture risk, with restricted cubic splines (RCS) applied to explore potential nonlinear associations. Subgroup analyses evaluated the consistency of these findings.

Results: The study included 1,107 participants (median age 37 years, 92.6% male). The median CD4 count was 547 cells/μL, and the median CD4/CD8 ratio was 0.7. Fragility fractures occurred in 185 participants (16.7%). Lower CD4 counts (<200 cells/μL) were associated with a higher risk of fractures (aHR = 2.78; 95% CI: 1.66-4.65; p < 0.001), as were lower CD4/CD8 ratios (<0.5) (aHR = 3.43; 95% CI: 2.16-5.44; p < 0.001). RCS indicated a curvilinear association, with increased fracture risk at CD4/CD8 ratios below 1.16. Subgroup analyses confirmed the stability of these associations.

Conclusion: Lower CD4 counts and CD4/CD8 ratios are linked to an increased risk of fragility fractures in PLHIV, underscoring the importance of immune function in bone health.