Early diagnosis and treatment of HIV critical for preventing neurologic infections, long-term study shows

Neurologic infections are more common among people living with HIV (PLWH) who have lower CD4 cell counts and higher viral loads than among those whose HIV is well-controlled, according to a long-term observational study in Canada.

About This Study

“Neurologic Infections in People with HIV: Shifting Epidemiological and Clinical Patterns” was published online on Sept. 12, 2023, in AIDS. The lead author is Miranda Mengyuan Wan, M.D., of the Department of Clinical Neurosciences of the Cumming School of Medicine at the University of Calgary, Alberta, Canada.

Key Research Findings

This retrospective observational cohort study evaluated the trajectory of neurologic infections among PLWH attending a single clinic in Southern Alberta, Canada, from 1995-2018. Data came from 2,910 PLWH, most of whom were white men (76% assigned male at birth, 55% white).

During 24,237 person-years of follow-up, there were 133 neurologic infections, 80% of them AIDS-defining. Most of the AIDS-defining neurologic infections were diagnosed prior to 2011 (77%), while 80% of non-AIDS defining infections were diagnosed between 2011 and 2018.

Cytomegalovirus (36%) and toxoplasmosis (33%) accounted for most AIDS-defining infections, while neurosyphilis (40%) and Varicella Zoster encephalitis (40%) were the most common non-AIDS-defining infections. (Most neurosyphilis cases were diagnosed in recent years, with 80% occurring between 2011-2018.) Over time, AIDS-defining infections declined but the incidence of non-AIDS-defining infections has remained flat.

The adjusted hazard ratio for neurologic infections was 2.5 for Black vs. white participants. PLWH with CD4 cell counts <200 cells/mm³ and HIV viral loads ≥200 copies/mL had more AIDS-defining infections than those with better HIV control. Mortality was higher among PLWH with a neurologic infection than among those without such an infection. Within one year of neurologic infection, 20 participants with AIDS-defining infections died compared to two participants with non-AIDS-defining infections.

Discussion Highlights and Implications for Practice

Study limitations reported by the researchers included the single-site design, low rates of certain infections, and lack of data on antiretroviral treatment adherence or vaccination history. Uptake of pneumococcal vaccine, which was provided free of charge, was high, while uptake of the varicella zoster vaccine, which was not government-funded, was lower.

The decline in AIDS-defining infections after the time when effective antiretroviral treatment was widely used confirms other studies’ results. The timing of neurosyphilis diagnoses is likely due to a local outbreak, the researchers said.

They pointed out that the lack of culturally competent care and stigma affect access to HIV care but some of the observed racial disparity may be related to early exposure to tuberculosis and toxoplasmosis among Black participants, most of whom came from areas of the world where these pathogens are common.

Study results show that early HIV treatment initiation not only improves HIV markers but is also important for preventing neurologic infections, authors emphasized.

By Barbara Jungwirth