Association between underlying health conditions and long COVID among non-hospitalized and hospitalized individuals as modified by health literacy: A multi-center study

OBJECTIVES: We investigated the effect modification of health literacy (HL) in ameliorating the negative impact of underlying health conditions (UHC) on long COVID among non-hospitalized and hospitalized survivors.

STUDY DESIGN: An online cross-sectional study was conducted in Vietnam from December 2021 to October 2022.

METHODS: A sample of 4507 participants recruited from 18 hospitals and health centers were those aged 18 or older, had contracted COVID-19 for at least 28 days, and were not in the acute phase of reinfection. Participants reported their long COVID symptoms, UHC, health literacy, socio-demographics, clinical parameters, the COVID-19 impact battery disability scale, and health-related behaviors. The logistic regression models were used to examine the associations and interactions.

RESULTS: Underlying health conditions were associated with a higher likelihood of long COVID in non-hospitalized participants (adjusted odds ratio, aOR = 2.10 [1.61, 2.61]; p < 0.001), and hospitalized ones (aOR = 2.26 [1.87, 2.73]; p < 0.001). In non-hospitalized participants, higher HL scores were significantly linked to a reduced likelihood of experiencing long COVID (aOR = 0.96 [0.95, 0.97]; p < 0.001). Furthermore, HL moderated the adverse effect of underlying health conditions (UHC) on long COVID in this group (aOR = 0.97 [0.94-0.99]; p = 0.042). In hospitalized participants, although higher HL scores were also associated with a lower risk of long COVID (aOR = 0.99 [0.98-0.99]; p = 0.036), HL did not significantly mitigate the negative impact of UHC on long COVID (aOR = 1.01 [0.99-1.03]; p = 0.332).

CONCLUSIONS: In non-hospitalized individuals, high health literacy ameliorated the negative impact of UHC on long COVID. Such effects of health literacy were not observed in hospitalized COVID-19 survivors.