Trends in knee osteoarthritis prevalence over a 10-year period in Japan: The ROAD study 2005–2015

Objective

This study aimed to clarify the trends in the prevalence of knee osteoarthritis (OA) and symptomatic knee OA among the general population using population-based cohort data from baseline and a survey 10 years later.

Design

The baseline survey of the Research on Osteoarthritis/Osteoporosis Against Disability (ROAD) study was conducted from 2005 to 2007; 3040 participants (1061 men and 1979 women; mean age 70.3 years) completed all OA examinations, including a questionnaire of medical information in the present/past and radiographic examination. The fourth survey was performed from 2015 to 2016; 2893 individuals (895 men and 1998 women, mean age 68.9 years) completed assessments identical to those at the baseline survey. Knee OA was defined using the Kellgren–Lawrence grading system.

Results

The prevalence of knee OA was 54.6 ​% (men, 42.0 ​%; women, 61.5 ​%) at the baseline survey and 39.3 ​% (men, 26.9 ​%; women, 44.9 ​%) at the fourth survey, with a significant decrease (p ​< ​0.0001). The prevalence of symptomatic knee OA was 24.3 ​% (men, 16.9 ​%; women, 28.3 ​%) at the baseline survey and 20.6 ​% (men, 14.2 ​%; women, 23.5 ​%) at the fourth survey, showing a similar decrease (p ​< ​0.0001). Thus, the prevalence of knee OA and symptomatic knee OA was lower at the fourth survey than at the baseline survey (p ​< ​0.01).

Conclusions

In the population-based survey with a 10-year interval, the prevalence of knee OA and symptomatic knee OA decreased significantly. This preferable change in OA may suggest rejuvenation in the current population and could contribute to a decrease in the occurrence of disabilities in the future.