Impact of long COVID on health-related quality of life among Japanese adults: findings of CARE Japan Study

Purpose We comprehensively assessed implications of long COVID on health-related quality of life (HRQoL) among Japanese adults and identified its associated factors. Methods This study used prospective cohort data from the CARE Japan Study between January 2022 and January 2023. The study outcome was HRQoL, measured using the 12-item Short Form questionnaire. Self-reported long COVID was the primary independent variable. We fit adjusted beta regression models to calculate beta regression coefficients with the 95% confidence intervals (CI) and average marginal effect (AME) to explore the determinants of HRQoL. We also performed latent class analysis to identify unobserved patterns of long COVID symptoms. Results The final sample size was 1,285 participants. Compared with participants without long COVID, HRQoL was significantly lower among patients with long COVID (β: −0.25; 95% CI: −0.36 to − 0.14; AME: −0.036). The effect of long COVID on HRQoL was most pronounced among respondents with pre-existing lung diseases (β: −0.72; 95% CI: −1.29 to − 0.16; AME: −0.114). In latent class analysis, we identified three subgroups of patients with long COVID: classes 1, 2, and 3. Compared with participants without long COVID, those belonging to class 1 (β: −0.47; 95% CI: −0.57 to − 0.36; AME: −0.065), class 2 (β: −0.48; 95% CI: −0.60 to − 0.35; AME: −0.066), and class 3 (β: −0.93; 95% CI: −1.06 to − 0.79; AME: −0.148) had poorer HRQoL. Conclusions Patients with long COVID had reduced HRQoL. Female sex, age ≤ 39 years, body mass index ≤ 18.5 kg/m ² , and pre-existing psychological disorders were associated with lower HRQoL.