Association between visceral fat and influenza infection in Japanese adults: A population-based cross-sectional study

Several studies have reported that obesity is associated with influenza infection; however, the role of visceral fat remains unclear. The aim of this study was to investigate the association between visceral fat and influenza infection in community-dwelling Japanese adults. A cross-sectional study was performed using data from an annual community-based health check-up conducted from May to June in 2019. In total, 1,040 Japanese adults aged 20-89 years were enrolled in this study. Influenza infection status was determined by participants' responses to a self-administered questionnaire. The visceral fat area (VFA) was measured using a bioimpedance-type visceral fat meter. Participants were classified into four groups using the following cut-off points: VFA < 100 cm.sup.2 was set as the reference category according to the Japanese criteria, 100 [less than or equal to] VFA < 150 cm.sup.2, 150 [less than or equal to] VFA < 200 cm.sup.2, and 200 cm.sup.2 [less than or equal to] VFA. Logistic regression models were used to assess the association between VFA and influenza infection. In total, 119 participants had influenza infections in the past year. In the multivariate adjusted model, a higher VFA was significantly associated with increased influenza infection; the adjusted odds ratio for 200 cm.sup.2 [less than or equal to] VFA was 5.03 [95% confidence interval (CI): 1.07-23.6], that for 150 [less than or equal to] VFA < 200 cm.sup.2 was 1.97 (95% CI: 0.71-5.45), and that for 100 [less than or equal to] VFA < 150 cm.sup.2 was 1.62 (95% CI: 0.84-3.12), compared with that for VFA < 100 cm.sup.2 (p for trend = 0.049). These findings were confirmed in the same cohort the following year. Our results suggest that visceral fat accumulation is associated with influenza infection. Large-scale prospective studies using diagnostic information for influenza infection are required to confirm this association.