Depression Subtypes in Persons with or at Risk for Symptomatic Knee Osteoarthritis

Objective

To identify depression subtypes in participants with or at-risk for symptomatic knee osteoarthritis (OA) and to evaluate differences in pain and disability trajectories between groups.

Methods

Participants (n=4486) were enrolled in the Osteoarthritis Initiative. Latent class analysis (LCA) was applied to the 20-Item Center for Epidemiological Studies Depression Scale measured at baseline to identify groups with similar patterns of depressive symptoms, and subtypes were assigned using poster probability estimates. The relationships between depression subtypes and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) pain and disability subscales were modeled over four years and were stratified by baseline knee OA status [symptomatic (n=1626) or at-risk (n=2860)].

Results

Four subtypes were identified: Asymptomatic (80.6%), Catatonic (5.3%), Anhedonic (10.6%), and Melancholic (3.5%). Catatonic and Anhedonic subtypes were differentiated by symptoms corresponding to psychomotor agitation and the inability to experience pleasure, respectively. The Melancholic subtype expressed symptoms related to reduced energy and movement, anhedonia, and other somatic complaints. Detectable mean differences in pain and disability compared to the Asymptomatic group were observed for the Anhedonic (1.5-2.3 WOMAC units) and Melancholic (4.8-6.6 WOMAC units) subtypes, and associations were generally larger in persons with symptomatic knee OA relative to those at-risk.

Conclusion

Among persons with or at-risk for symptomatic knee OA, there is evidence of depression subtypes characterized by distinct clusters of depressive symptoms that have differential effects on reports of pain and disability over time. Thus, findings imply depression interventions could be optimized by targeting the specific symptomology these subtypes exhibit.