Introduction: Little is known about the clinical status of persons with HIV who re-engage in care after an interruption. We evaluated the immunologic and clinical characteristics of individuals re-engaging in care within the Swiss HIV Cohort Study.

Methods: Participants who re-engaged in care after an interruption >14 months with a viral load ≥100 copies/mL were classified as having interrupted antiretroviral therapy (ART). We defined late re-engagement as re-engaging with a CD4 cell count of <350 cells/µL or a new Centers for Disease Control and Prevention stage C disease. Linear and logistic regression models with restricted cubic splines were used to estimate the mean CD4 cell count at re-engagement and the probability of late re-engagement as a function of care interruption duration.

Results: Of 14,864 participants with a median follow-up of 10.2 years (interquartile range 4.7-17.2 years), 2768 (18.6%) interrupted care, of whom 1489 (53.8%) re-engaged. Among those re-engaging, 62.3% had interrupted ART. For participants who interrupted ART, the mean CD4 count declined from 374 cells/µL [95% confidence interval (CI): 358 to 391 cells/µL] before the interruption to 250 cells/µL (95% CI: 221 to 281 cells/µL) among those re-engaging after 14 months, and to 185 cells/µL (95% CI: 160 to 212 cells/µL) among those re-engaging after 60 months. The estimated risk of late re-engagement in care was 68.6% (95% CI: 62.3% to 74.4%) for participants who interrupted ART for 14 months and 75.2% (95% CI: 68.9% to 80.6%) for those who interrupted ART for 60 months.

Conclusions: Although HIV care interruptions are not very common in Switzerland, most persons with HIV re-engaging after interrupting ART return with late-stage HIV.