The prevalence and basic characteristics of knee pain in community-dwelling independent elderly: A complete survey.

Objectives　The objectives of this study were to determine the prevalence of knee pain in independent community-dwelling elderly people and to examine the basic characteristics (sex and age) of those experiencing knee pain.Methods　Survey on the health status and lifestyle habits was conducted for all (6,790) independent elderly who were 65 years or older, living in Tsuru City, Yamanashi Prefecture, Japan. The survey was carried out using a mailing questionnaire for 1 month from January 12 to February 11, 2016. Knee pain was defined as subjective pain in and around the knee joint in either one or both knees, on most days during the past month. Participants answered "Yes" if they were experienced knee pain, and "No" if they did not experience knee pain. Sex and age were investigated as basic characteristics of the participants by the questionnaire. The prevalence rate of knee pain was calculated as follows: the total number of people with knee pain divided by the total number of the respondents in the study. To examine the relationships between knee pain and age or sex, these basic characteristics were analyzed using a Chi-square test for the prevalence of knee pain within sex and age groups.Results　The number of survey respondents was 5,328 (response rate: 78.5%). The number of valid respondents with complete data was 5,186 (valid response rate: 76.4%). The number of subjects who responded "with knee pain" was 1,733. The prevalence rate of knee pain was 33.4%. In addition, sex and age demonstrated strong associations with the prevalence of knee pain (both, P<0.001). In other words, the prevalence rate was higher in the elderly women than in elderly men and increased with age.Conclusion　The present study suggested that one in three independently living elderly who live in medium-sized local municipalities in Japan experience chronic knee pain. The basic characteristics of a community-dwelling independent elderly with knee pain are to be a woman and older age.