CD8A and major depressive disorder: Results of logistic regression models with restricted cubic splines showed there was a significant nonlinear dose–response relation between sleep duration and physical frailty among PWH after adjusting for age, gender, smoking, alcohol consumption, depression, neurocognitive impairment, comorbidities, and current CD4+ and CD8+ T-cell counts (Pnonlinearity = .007) (Figure 2A).