Rate of and Risk Factors for Loss to Follow Up in HIV-Infected Patients in Korea: The Korea HIV/AIDS Cohort Study

Background: Owing to antiretroviral therapy (ART), acquired immune deficiency syndrome (AIDS)-related mortality has significantly decreased. Retaining in care is an essential step for human immunodeficiency virus (HIV) care cascade. This study investigated the incidence of and risk factors for loss to follow-up (LTFU) in Korean people living with HIV (PLWH). Materials and Methods: Data from the Korea HIV/AIDS cohort study (including prospective interval cohort and retrospective clinical cohort) were analyzed. LTFU was defined as not visiting the clinic for more than 1 year. Risk factors for LTFU were identified using the Cox regression hazard model. Results: The study enrolled 3,172 adult HIV patients (median age, 36 years; male 92.97%). The median CD4 T cell count at enrollment was 234 cells/mm3 (interquartile range [IQR]: 85 -373) and the median viral load at enrollment was 56,100 copies/mL (IQR: 15,000 -203,992). The total follow-up duration was 16,487 person-years, and the overall incidence rate of LTFU was 85/1,000 person-years.In the multivariable Cox regression model, subjects on ART were less likely to have LTFU than subjects not on ART (hazard ratio [HR] = 0.253, 95% confidence interval [CI]: 0.220 -0.291, P <0.0001). Among PLWH on ART, female sex (HR = 0.752, 95% CI: 0.582 -0.971, P = 0.0291) and older age (>50: HR = 0.732, 95% CI: 0.602 -0.890; 41 -50: HR = 0.634, 95% CI: 0.530 -0.750; 31 -40: HR = 0.724, 95% CI: 0.618 -0.847; <= 30: reference, P <0.0001) were associated with high rate of retention in care. The viral load at ART initiation >= 1,000,001 (HR = 1.545, 95% CI: 1.126 -2.121, <= 10,000: reference) was associated with a higher rate of LTFU. Conclusion: Young and male PLWH may have a higher rate of LTFU, and an increased rate of LTFU may induce virologic failure.