Objective: Obesity and arthritis are leading chronic conditions, but comorbidity of these conditions and their interaction leading to depression have not been fully investigated. The purpose of this study is to determine the degree to which excess body weight effect-modifies the relationship between arthritis and depressive symptoms.

Methods: We used the data of 8677 men and 8820 women aged 20 or older, who completed a depression screening and general medical condition interview as a part of the National Health and Nutrition Examination Survey, 2005–2012. Depression was ascertained using the Patient Health Questionnaire-9 (PHQ-9); a PHQ-9 score of 15 or higher was defined as indicative of depression.

Results: Arthritis was reported in 26.5% (SE = 0.9) of men and 36.9% (SE = 1.4) of women. The association between depression and arthritis was not significant among healthy weight women, but significant among overweight and obese women. The prevalence ratios (PRs) of depression among arthritis-free women were 1.00 (reference) for healthy weight, 1.43 (0.85–2.42) for overweight, and 1.99 (1.23–3.23) for obese women. For women with arthritis, the PRs were 1.16 (0.63–2.12) for healthy weight, 3.80 (2.24–6.45) for overweight and 3.73 (2.30–6.05) for obese women. The intensifying effect from excessive body weight on the association between arthritis and depression was less salient among men than women.

Conclusions: The association between arthritis and depression is intensified significantly by increased body weight, in particular, among women.