Modifiable risk factors for knee osteoarthritis (OA) have not been studied in detail. This study aimed to determine lifestyle-related modifiable factors of symptomatic knee osteoarthritis in an East Asian population.
This 5-year cohort study involved 11,091 individuals (age range 40-72 years) living in the Murakami region of Niigata, Japan, who did not have a history of knee OA. At baseline, information on sociodemographic characteristics, body size, lifestyle, and living condition was obtained using a self-administered questionnaire.
Incident symptomatic knee OA observed at hospitals and orthopaedic clinics in the five years to 2016. Clinical grades of knee OA were based on the Kellgren-Lawrence scale. P for trend was assessed to examine linear associations between predictors and the outcome in multiple logistic regression analysis.
The mean age of participants was 58.1 (SD 9.3) years. The number of cases of grade 2 or more incident knee OA was 429. In men, older age (P for trend < 0.0001), higher BMI (P for trend < 0.0001), higher METs score (P for trend = 0.0150), less smoking (P for trend = 0.0249), and lower green tea consumption (P for trend = 0.0437) were associated with incident knee OA. In women, older age (P for trend < 0.0001), higher BMI (P for trend < 0.0001), and alcohol consumption (P = 0.0153) were associated with incident knee OA.
Several lifestyle-related factors were found to be associated with incident knee OA and exhibited sex-dependent differences. In particular, higher consumption of green tea was associated with a lower incidence of knee OA in men.