Multifactorial determinants of lost to follow-up in antiretroviral therapy: evidence from a case-control study in...

Loss to follow-up (LTFU) remains a major challenge in achieving sustained HIV care. Understanding individual and structural factors influencing disengagement is essential to improve retention, particularly in low- and middle-income settings. This study aimed to identify predictors of LTFU among adults receiving antiretroviral therapy (ART) in western Mexico.

A case-control study was conducted among adults with HIV treated at a tertiary hospital. Cases met the national definition of LTFU (≥ 90 days beyond the expected clinic visit or pharmacy refill), while controls were retained patients during the same period. A total of 919 participants were included (148 LTFU, 771 retained). Multivariable logistic regression identified factors associated with LTFU.

Median age was 42 years (IQR 34, 51) and 88% were male. The multivariable analysis identified that age was associated with lower risk of LTFU (adjusted odds ratio [aOR] per year, 0.94; 95% CI, 0.91-0.96). Secondary ART resistance (aOR, 4.03; 95% CI, 1.59-9.99), hard-drug use (aOR, 2.57; 95% CI, 1.68-3.93), psychiatric disorders (aOR, 3.58; 95% CI, 2.23-5.72), lower educational level (≥ upper secondary vs. no formal education/primary: aOR, 2.30; 95% CI, 1.34-3.94), emergency department visits (aOR, 2.63; 95% CI, 1.72-4.04), and years living with HIV (aOR per year, 1.06; 95% CI, 1.02-1.10) were associated with higher odds of LTFU.

These findings highlight the role of psychosocial and structural determinants of LTFU, underscoring the need for integrated interventions addressing education, mental health, and substance use to improve retention in HIV care in Mexico.