Knee pain and future self-reliance in older adults: evidence from a community-based 3-year cohort study in Japan

Although knee pain is common in older persons and can cause ambulatory limitation, its impact on self-reliance has rarely been examined in Japan, particularly in a community setting. The aim of this 3-year cohort study was to investigate the association of knee pain with dependence in activities of daily living (ADL) and mortality in community-dwelling older Japanese adults. In 2005, presence of knee pain was assessed by a home visit survey of 1391 older adults aged 65 years or older (participation proportion = 97.3%). A total of 1265 participants who were ADL-independent at baseline were followed for 3 years, and information on outcomes, namely death and dependence in ADL, was collected. Participants who always had knee pain were more likely to become dependent in ADL than those who reported no knee pain (multivariate-adjusted OR, 1.98; 95% CI, 1.03-3.83); however, always having knee pain was not associated with mortality or a composite outcome of ADL dependence and death. Further analyses of each component of ADL dependence revealed that knee pain was associated with a need for assistance at home (long-term care eligibility, bathing, dressing, and transferring), but not with institutionalization. The participants were highly representative of the target population and the rate of follow-up was almost perfect (99.4%). The results suggest that knee pain is associated with future dependence in ADL, particularly a need for assistance at home.