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. Author manuscript; available in PMC: 2022 Apr 1.
Published in final edited form as: Arthritis Care Res (Hoboken). 2021 Mar 13;73(4):566–573. doi: 10.1002/acr.24151

Figure 1. A Directed Acyclic Graph to Describe the Mediation Effect between Symptomatic Knee OA and All-cause Mortality.

Figure 1.

OA, osteoarthritis; PCS of QoL, physical component summary score of quality of life

Indirect effect: effect of symptomatic knee OA on all-cause mortality through its effect on mediators (i.e., disability and PCS of QoL)

Direct effect: effect of symptomatic knee OA on all-cause mortality not through its effect on mediators (i.e., disability and PCS of QoL)

Total effect: sum of indirect and direct effects

Confounders: confounders of association between symptomatic knee OA and all-cause mortality (i.e., age, race, sex, body mass index, education level, weekly alcohol consumption, smoking habits, history of knee injury, comorbidities, depressive symptom and widespread pain)