Longitudinal Trajectories of Depressive Symptoms Among Patients With Knee Osteoarthritis: The Role of Pain Intensity.

Background: Pain is the primary symptom of knee osteoarthritis (KOA), significantly associated with depressive symptoms. Whether the early pain intensity could distinguish different trajectories of depressive symptoms is not well understood among patients with KOA.

Aims: To identify heterogeneous depressive symptoms trajectories among patients with KOA, and investigate the association between depressive symptoms subgroups and pain intensity.

Design: Secondary analysis of a cohort sample.

Setting: Three waves of data from the China Health and Retirement Longitudinal Study was collected in 28 provinces across China.

Participants: 702 patients with KOA aged ≥ 45 years completed the Center for Epidemiologic Studies Depression Scale biennially from 2011 to 2015.

Methods: Latent class growth analysis was performed to identify the optimal trajectory shape and number of classes. Multinomial logistic regression analysis was conducted to compare pain intensity across the trajectories.

Results: Four distinct trajectories were identified as follows: no depressive symptoms, highly stable, decreasing, and increasing. In multivariate analysis, compared with the "no depressive symptoms" class, patients in the "highly stable" class and "increasing" class were more likely to report moderate pain (p < 0.05) and severe pain (p < 0.05). In addition, there was no significant difference in pain intensity between "no depressive symptoms" class and "decreasing" class (p > 0.05).

Conclusions: These results suggest important heterogeneity in depressive symptom trajectories among patients with KOA. Pain intensity could predict different depressive symptom trajectories in patients with KOA. Efforts to improve the depressive symptoms in patients with KOA must incorporate strategies to address pain.