Associations between cytomegalovirus infection and functional impairment and frailty in the BELFRAIL Cohort

Objectives: To investigate whether an observed association between cytomegalovirus (CMV) exposure and functional impairment and frailty in older adults is reproducible in a cohort of individuals aged 80 and older.

Design: The baseline results of the BELFRAIL study, a prospective observational cohort study, were analyzed.

Setting: Three well-circumscribed areas of Belgium.

Participants: Five hundred sixty-seven persons aged 80 and older recruited by 29 general practitioners.

Measurements: Serum samples were assayed for levels of CMV immunoglobulin (Ig)G antibodies, interleukin (IL)-6, and C-reactive protein. Measures of functional impairment were the Physical Performance Battery, Activities of Daily Living, and the Mini-Mental State Examination. Frailty was assessed using the Fried criteria.

Results: Positive CMV serology was found in 74% of the population, 61% of whom had a high anti-CMV IgG titer (>250 IU/mL). CMV infection was not associated with functional or cognitive impairment. Positive CMV serology was negatively associated with prevalent frailty after adjusting for age, sex, level of education, comorbidity, smoking status, body mass index, and IL-6 level. High levels of anti-CMV IgG were associated with functional impairment. In the adjusted models, this relationship was no longer statistically significant. There was no association between prevalent frailty or cognitive impairment and high anti-CMV IgG titers.

Conclusion: The findings of previous studies could not be confirmed. Moreover, positive CMV serology was found to be negatively associated with frailty. These apparently contradictory results may reflect a survival effect because the current study population was considerably older than the populations of older adults in previous studies.