Fig. 1

Path diagram for pain phenotype transition from baseline to 24-month follow-up through latent transition model. Five WOMAC items at baseline and 24-month follow-up were used to distinguish different pain phenotypes at baseline and 24-month follow-up, respectively. Baseline characteristics (e.g., sex, age and BMI) were used in the log binomial model and latent transition model for analyzing the factors associated with the 24-month pain phenotype and phenotype transitions. BMI, body mass index; CES-D, Center for Epidemiological Studies-Depression; KL garde, Kellgren and Lawrence grade; WOMAC, Western Ontario and McMaster Universities Osteoarthritis Index