The loss to follow-up of participants excluded from the NAMSAL trial: a retrospective cohort study

Despite advances in Human Immune Virus (HIV) treatment, loss to follow-up (LTFU) remains a challenge, particularly in sub-Saharan Africa. Understanding its predictors is vital to improve retention in care and hence, better treatment outcomes. While clinical trials result in better follow-up and possibly better treatment for the patients included, little data is available on those excluded. We aimed to assess the LTFU rate and associated factors among patients excluded from the New Antiretroviral and Monitoring Strategies in HIV-infected Adults in Low-income Countries (NAMSAL) trial. A hospital-based retrospective cohort study was conducted from December 2022 to July 2023 across three health facilities in Yaoundé, Cameroon. Data from 132 patients who were excluded from the NAMSAL trial was analyzed using R software. LTFU was defined as no recorded data for three months or more after missing scheduled visits. Kaplan-Meier estimates and Cox proportional hazards regression were used to describe and analyze LTFU rates and associated factors, with a p-value < 0.05 considered statistically significant. We analyzed data from 132 (51% male) participants excluded from the NAMSAL trial, with a median age of 34 (IQR: 23-51) years. Most participants were employed (63.6%) and single (72.7%). This population was mostly in WHO clinical stages 1 (37.1%) and 3 (33.3%), and 57.6% had baseline viral loads below 100,000 copies/mL. More than half (74, 56.1%) were LTFU over the study period. The median time to LTFU was 108 weeks. Cox regression analysis revealed that being female (aHR = 0.27, [95% CI 0.13-0.52]; p˂0.001) and having a high baseline viral load (aHR = 0.34, [95% CI 0.16-0.71]; p = 0.004) were associated with reduced LTFU risk. The high LTFU rate among excluded NAMSAL trial patients highlights the need for targeted retention strategies, particularly for male patients, patients with multiple comorbidities and advanced disease stages. These findings can inform interventions to improve HIV care retention in Cameroon.