Study design and participants
This was a cross-sectional study based on a survey on 34,564 community-dwelling older adults aged ≥ 60 years in Iwamizawa, a regional city in Hokkaido, northern Japan. This study included older adults who participated in wellness checkups in CHEER Iwamizawa (a research project titled “Checkup to discover HEalth with Energy for senior Residents” in Iwamizawa) in October 2020. The participants of CHEER Iwamizawa were recruited through a public relations magazine published by the city council and flyers posted at major public facilities in the city. In addition, local government employees visited older adults’ social clubs to describe the study’s purpose and recruit participants. The survey content was explained verbally and in writing to the participants, and written informed consent was obtained prior to the survey. This study was conducted in accordance with the Declaration of Helsinki and approved by the Ethics Committee of the Faculty of Dental Medicine, Hokkaido University (approval number: 2020–9).
Evaluation of outcome
OHRQoL was evaluated using the Japanese version of the GOHAI46. The GOHAI consists of 12 questions rated on a five-point Likert scale assessing the frequency of oral health-related problems over the past three months. The total score ranges from 12 to 60; the higher the score, the higher the OHRQoL. The median scores, as per the GOHAI national norms for Japanese individuals, are 56.0 and 52.5 for men aged 60 − 69 years and 70 − 79 years, respectively, and 54.0 and 53.0 for women aged 60–69 years and 70 − 79 years, respectively. Therefore, in this study, participants scoring below these cutoff values were defined as the poor OHRQoL group, while the remaining participants were assigned to the good OHRQoL group.
Defining the risk of poor OHRQoL
CS and LEH were defined as risk factors for poor OHRQoL, and their presence or absence was examined using self-administered questionnaires….