Sato S1, Nakamura M2, Nemoto Y3, Takeda N4, Maruo K5, Fukuda Y6, Sawada S3, Kitabatake Y7, Arao T8
1University of Human Arts and Sciences, Faculty of Health Sciences, Saitama, Japan, 2Tokyo Metropolitan Institute of Gerontology, Tokyo, Japan, 3Waseda University, Graduate School of Sport Sciences, Tokorozawa, Japan, 4Kougakuin University, Division of Liberal Arts, Tokyo, Japan, 5University of Tsukuba, Faculty of Medicine, Tsukuba, Japan, 6Teikyo University, Graduate School of Public Health, Tokyo, Japan, 7Saitama Prefectural University, School of Health and Social Services, Koshigaya, Japan, 8Meiji Yasuda Life Foundation of Health and Welfare, Tokyo, Japan
Background: Knee pain is a common health problem among older adults. It affects not only an individual's daily activities, but also the social security cost. Therefore, preventing knee pain in older adults is a major public health issue in Japan.
Purpose: The purpose of this 2-year longitudinal study was to examine the frequency and risk factors of knee pain in community-dwelling independent older adults.
Methods: In January 2016, a baseline survey was conducted for every independent older adult (6,677) living in a local municipality in Japan. The survey used a self-administered questionnaire by mail. Among 5,131 respondents who provided complete data (response rate: 76.8%), 3,453 older adults without knee pain were followed up for 2 years. In January 2018, a follow-up survey was conducted using the same questionnaire as the baseline survey. Survey items included basic attributes, health status, lifestyle, knee pain, physical activity, and sitting time. Knee pain was assessed by asking “Have you experienced pain in one of the left and right knees on most days in the past month?” Those who responded “no” were defined as “without knee pain,” while those who responded “yes,” as “with knee pain.” Physical activity was assessed using the international physical activity questionnaire. Sitting time was obtained by summing the time spent on each of five activities such as reading, conversation with family, PC use, TV watching, and lying down. Physical activity was classified into two groups based on the international recommendation of 150 minutes of physical activity by the World Health Organization. Sitting time was classified into two groups based on median value of the subjects. Prior to analysis, missing values were supplemented by multiple imputation. The risk factors for knee pain were evaluated by multiple logistic regression analysis. The odds ratios (OR) and 95% confidence interval (CI) were also calculated. In the analysis, the presence or absence of knee pain was the dependent variable, physical activity, sitting time, lifestyle, and body mass index (BMI) were the independent variables; age, sex, marital status, educational history, and current disease status were the adjustment variables.
Results: Among 3,453 subjects, 3,351 responded (recovery rate: 97%) to the follow-up survey. Among these, 640 older adults (incidence rate: 19.1%) were identified to have an incidence of knee pain during the follow-up period. Risk factors for the onset of knee pain were physical activity (OR: 1.61, 95% CI: 1.28－2.02) and BMI (OR: 1.66, 95% CI: 1.29－2.14) in all subjects. The same result was obtained by analyzing complete data.
Conclusion(s): The incidence rate of knee pain for 2 years was 19.1% in local community-dwelling older adults. Risk factors for the incidence of knee pain in this population were physical inactivity and obesity.
Implications: These results can be useful for estimating the incidence of knee pain among older adults, and for developing knee pain prevention measures in other municipalities in Japan.
Keywords: knee pain, old adults, risk factor
Funding acknowledgements: This study was conducted with the Grants-in-Aid for scientific research. In this study, No potential COI to disclose.
Purpose: The purpose of this 2-year longitudinal study was to examine the frequency and risk factors of knee pain in community-dwelling independent older adults.
Methods: In January 2016, a baseline survey was conducted for every independent older adult (6,677) living in a local municipality in Japan. The survey used a self-administered questionnaire by mail. Among 5,131 respondents who provided complete data (response rate: 76.8%), 3,453 older adults without knee pain were followed up for 2 years. In January 2018, a follow-up survey was conducted using the same questionnaire as the baseline survey. Survey items included basic attributes, health status, lifestyle, knee pain, physical activity, and sitting time. Knee pain was assessed by asking “Have you experienced pain in one of the left and right knees on most days in the past month?” Those who responded “no” were defined as “without knee pain,” while those who responded “yes,” as “with knee pain.” Physical activity was assessed using the international physical activity questionnaire. Sitting time was obtained by summing the time spent on each of five activities such as reading, conversation with family, PC use, TV watching, and lying down. Physical activity was classified into two groups based on the international recommendation of 150 minutes of physical activity by the World Health Organization. Sitting time was classified into two groups based on median value of the subjects. Prior to analysis, missing values were supplemented by multiple imputation. The risk factors for knee pain were evaluated by multiple logistic regression analysis. The odds ratios (OR) and 95% confidence interval (CI) were also calculated. In the analysis, the presence or absence of knee pain was the dependent variable, physical activity, sitting time, lifestyle, and body mass index (BMI) were the independent variables; age, sex, marital status, educational history, and current disease status were the adjustment variables.
Results: Among 3,453 subjects, 3,351 responded (recovery rate: 97%) to the follow-up survey. Among these, 640 older adults (incidence rate: 19.1%) were identified to have an incidence of knee pain during the follow-up period. Risk factors for the onset of knee pain were physical activity (OR: 1.61, 95% CI: 1.28－2.02) and BMI (OR: 1.66, 95% CI: 1.29－2.14) in all subjects. The same result was obtained by analyzing complete data.
Conclusion(s): The incidence rate of knee pain for 2 years was 19.1% in local community-dwelling older adults. Risk factors for the incidence of knee pain in this population were physical inactivity and obesity.
Implications: These results can be useful for estimating the incidence of knee pain among older adults, and for developing knee pain prevention measures in other municipalities in Japan.
Keywords: knee pain, old adults, risk factor
Funding acknowledgements: This study was conducted with the Grants-in-Aid for scientific research. In this study, No potential COI to disclose.
Topic: Health promotion & wellbeing/healthy ageing; Older people; Pain & pain management
Ethics approval required: Yes
Institution: University of Human Arts and Sciences
Ethics committee: Ethics Review Committee of University of Human Arts and Sciences
Ethics number: Ethics approval number 543
All authors, affiliations and abstracts have been published as submitted.
