Prevalence and Risk Factors Associated with Keratoconjunctivitis Sicca in People Living with Human T-Leukemia Virus Type 1: A Systematic Review and Meta-Analysis

To estimate the global prevalence of keratoconjunctivitis sicca (KCS) among Human T‑cell lymphotropic virus type 1 (HTLV‑1)–infected individuals and to evaluate diagnostic methods and research gaps within ocular immunology. A systematic review and meta‑analysis were performed per PRISMA. We searched PubMed/MEDLINE, Embase, Web of Science, Scopus, Cochrane CENTRAL, SciELO, LILACS, DOAJ, OpenGrey, and CAPES through December 2023. Eligible studies were cross‑sectional or cohort investigations reporting KCS prevalence in confirmed HTLV‑1–seropositive adults (ELISA or Western blot). Two independent reviewers screened 289 records, with discrepancies resolved by a third. Eight studies met the inclusion criteria. The random‑effects pooled prevalence of KCS in HTLV‑1 infection was 34.6% (95% CI: 19.8%–51.0%; I² = 97.2%). Patients with HTLV‑1–associated myelopathy/tropical spastic paraparesis (HAM/TSP) exhibited a higher prevalence (prevalence ratio [PR]: 2.01; 95% CI: 1.73–2.31). Diagnostic approaches in six studies employed Rose Bengal staining, Schirmer I test, and tear film breakup time. Approximately one in three HTLV‑1–infected patients develop KCS, with elevated risk in those with HAM/TSP. Persistent heterogeneity—driven by diagnostic variability, geographic factors, and demographic differences—underscores the need for standardized criteria, inclusion of diverse populations, and further research on proviral load, gender, and ethnicity to inform ocular practice, including immunology.