[Characterization of immune reconstitution inflammatory syndrome in a Mexican cohort].

Background: Immune reconstitution inflammatory syndrome (IRIS) is an exaggerated inflammatory response to previously acquired opportunistic pathogens, causing clinical deterioration in the first months after starting antiretroviral therapy, contributing to morbidity and mortality in people living with HIV (PLHIV). In Mexico, data are limited, but IRIS has been reported in 11.4 - 27% of patients, with Varicella zoster as the most frequently associated pathogen and a mortality rate of 4.9 deaths per 100 person-years. Objective: To describe clinical and etiological characteristics of immune reconstitution inflammatory syndrome in patients treated at a tertiary care hospital in Mexico. Material and methods: A cross-sectional, retrospective study, through the review of medical records from the Hospital de Especialidades CMN Siglo XXI, including patients with recent HIV diagnosis between January 1, 2017, and June 31, 2023. Variables were recorded and analyzed using SPSS v.25, with p < 0.05 considered statistically significant. Results: 55 patients were included; 45 (81.8%) presented unmasking IRIS, with a median onset time of 6 (4-12) weeks after starting ART. M. tuberculosis was the most frequent pathogen (27.3%). There were eight deaths (14.5%), due to pneumocystis pneumonia and cerebral toxoplasmosis. Corticosteroid use was associated with higher mortality. Conclusions: The most frequent pathogens associated with IRIS were M. tuberculosis and cytomegalovirus. The case-fatality rate was 14.5%, higher than that reported in other Mexican series.