Predictive symptoms associated with the development of radiographic knee osteoarthritis: a 10-year longitudinal study from the Iwaki cohort

This 10-year longitudinal cohort study aimed to investigate the annual rate of development of radiographic knee osteoarthritis (drKOA) and its predictive symptoms in the general Japanese population. A total of 263 volunteers (154 women) from the Iwaki Health Promotion Project were followed up over 10 years. Standing anteroposterior knee radiographs were obtained and the Kellgren–Lawrence grade was evaluated. drKOA was defined as a change from grade 0 or 1 to ≥2 over 10 years. Knee symptoms were evaluated using the Knee injury and Osteoarthritis Outcome Score at baseline. Logistic regression analyses were performed to identify symptoms related to drKOA, and a predictive formula was created based on the associated symptoms. The overall incidence of drKOA was 52.9% (annual rate, 4.34%). Regression analysis revealed that predictive symptoms for drKOA were stiffness [ p ​= ​0.033; odds ratio (OR) ​= ​1.89], frequent pain ( p ​= ​0.024; OR ​= ​1.38), difficulty in ascending stairs, jumping, twisting, and kneeling ( p ​= ​0.009–0.046; OR ​= ​1.71–2.78), and poor knee-related quality of life ( p ​< ​0.001–0.005; OR ​= ​1.53–2.18). Furthermore, the prediction formula created using these predictive symptoms demonstrated an area under the curve of 0.663, a cutoff value of 97 out of 100 points, an OR of 2.99, p ​< ​0.001, sensitivity of 0.676, and specificity of 0.589. The annual incidence rate of drKOA was 4.34% in the general Japanese population. The identified symptoms would be useful to predict the drKOA and consider the etiology of the early phase of this disease. • Annual rates of development of radiographic knee osteoarthritis (drKOA) and accelerated drKOA were 4.34% and 0.77%, respectively. • Identified symptoms would be useful to predict drKOA.