Better olfaction was associated with lower healthcare expenditure among physically independent Japanese community-dwelling older adults: the Yanai Study

Yujiro Kose^1*Yoichi Hatamoto²Rie Tomiga-Takae³Yukari Kimuro⁴Ryo Aoyagi³Hikaru Kawasaki³Takaaki Komiyama⁵Mamiko Ichikawa⁶Katsutoyo Fujiyama⁷Yoshiro Murata⁸Masahiro Ikenaga⁹Yasuki Higaki³

• ¹National Institute of Fitness and Sports in Kanoya, Kanoya, Japan
• ²National Institutes of Biomedical Innovation, Health and Nutrition, Ibaraki, Ôsaka, Japan
• ³Fukuoka University, Fukuoka, Fukuoka, Japan
• ⁴Nishikyushu University, Kanzaki, Saga, Japan
• ⁵Osaka University, Suita, Ōsaka, Japan
• ⁶Teikyo University, Itabashi, Tōkyō, Japan
• ⁷yanai city hall, Yanai, Japan
• ⁸Emu Kankyo Design System Co., Ltd., Fukuoka, Japan
• ⁹Nishinippon Institute of Technology, Kitakyushu, Fukuoka, Japan

Objective: We aimed to determine whether olfaction was associated with healthcare expenditure among physically independent community-dwelling older adults.This cross-sectional study included 162 community-dwelling older adults (mean age 70.2 ± 5.4 years; 48 men, 114 women) from the 2015 Yanai Study. Of these, we followed 71 participants (mean age 70.0 ± 5.7 years; 26 men, 45 women) in a longitudinal pilot study over 1.5 years, which measured healthcare expenditure from May 2015 to October 2016. Olfaction was examined with the Odor Stick Identification Test for Japanese people.The cross-sectional analysis showed better overall olfaction was significantly associated with lower orthopedics expenditure at baseline when adjusted for covariates (f = 2.19, p = 0.115, p for linear trend = 0.048). This association remained significant in the model adjusted for final covariates (f = 2.30, p = 0.105, p for linear trend = 0.034). Better olfaction scores (≥8) were associated with lower orthopedics expenditure in the final covariates model (odds ratio 0.780, 95% confidence interval: 0.612-0.994; p = 0.045). The longitudinal analysis showed a baseline olfaction score ≥8 was associated with lower total healthcare expenditure, outpatient visit expenditure, and internal medicine expenditure independent of covariates over 1.5 years in the model adjusted for final covariates (group × time interaction: f = 4.05, p = 0.021; f = 4.34, p = 0.016; and f = 6.20, p = 0.005).Conclusions: Both the cross-sectional and longitudinal analyses suggested that better olfaction ability is associated with lower healthcare expenditure. These results may help to increase awareness of olfactory dysfunction at an earlier stage among physically independent community-dwelling older adults.