Pain Severity as a Mediator of the Association Between Depressive Symptoms and Physical Performance in Knee Osteoarthritis
Feb 7, 2019
Published in: Arthritis Care & Research (2019). doi: 10.1002/acr.23898
Posted on RAND.org on June 14, 2019
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.
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)].
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.
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.