For people with rheumatoid arthritis and osteoarthritis, depression may be associated with pain sensitivity and with less effective coping with the illness. Zautra and Smith [1
] used a measure of depressive symptom severity (the Mental Health Inventory) to assess the impact of depression in a volunteer sample with rheumatoid arthritis or osteoarthritis. Depressive symptoms in people with rheumatoid arthritis predicted elevated pain ratings, negative affect, negative life events, perceived stress and (decreased) positive event ratings. In osteoarthritis, depressive symptoms were found to predict higher levels of arthritis pain and negative affect. Anderson and others [2
] used a depression adjective list to assess depressive symptom severity in a clinical sample with rheumatoid arthritis. They did not find that depression predicted pain severity, but found that it did predict observer-rated functional status.
Clinically diagnosed depressive disorders, as distinct from symptom ratings, and as defined by the American Psychiatric Association's Diagnostic and Statistical Manual of Mental Disorders (DSM-IV-TR) [3
] are more directly related to clinical need than are symptom ratings. The first study to examine associations between arthritis and mental disorders in a community population was conducted by Wells and others [4
] using data from one of five sites comprising the Epidemiologic Catchment Area studies, which were conducted in the United States in the 1980s. By epidemiological standards, the single site sample was not large, n = 3132 of whom 2554 were included in the analyses. Self-reported arthritis occurred with a frequency of18%, and a higher lifetime prevalence of affective, anxiety and substance use disorders were seen in this group than in subjects reporting no chronic conditions. Notably, this paper included a broad definition of substance use disorder – including both abuse and dependence on alcohol and other substances. The overall frequency of this category was 17.3% in subject without chronic conditions and 30.7% in subjects with arthritis [5
]. An association was seen for lifetime, but not recent substance use disorders.
Baumeister & Härter conducted an investigation that integrated data from the German National Health Interview and Examination Survey, which used the Composite International Diagnostic Interview (CIDI), with data collected from inpatients with musculoskeletal conditions. They demonstrate a higher than expected prevalence of mood and anxiety disorders in the clinical subjects [6
]. An elevated prevalence of substance use disorder was not found. McWilliams and others used data from another community study, the National Comorbidity Survey (NCS), to examine associations between "severe arthritis, rheumatism, or another bone or joint disease" and mood and anxiety disorders [7
]. This study used the University of Michigan version of the CIDI to evaluate mental disorder prevalence. Both mood (major depression, dysthymia) and anxiety (generalized anxiety disorder, panic disorder, simple phobia, social phobia, agoraphobia and post-traumatic stress disorder) disorders had a higher prevalence in the arthritis, rheumatism or bone disease group than was seen in the general population. The strength of association was higher for anxiety than for mood disorders. This result was replicated subsequently using data from the Midlife Development in the United States Survey (MIDUS), which employed a brief predictive version of the CIDI and also included self-reported diagnoses of arthritis [8
]. In the NCS analysis, a logistic regression model predicting disability was reported. Having arthritis, rheumatism or other bone or joint disease and having a psychiatric condition made an independent contribution to disability [7
One record linkage study suggested that depressive episodes often precede completed suicides in people with rheumatoid arthritis and osteoarthritis, highlighting the potential clinical significance of depression in this population [9
]. Another indication of clinical significance was reported by Löwe and others, who found that depression (in this study evaluated using the Patient Health Questionnaire [10
]) contributed to disability in a way that was independent of severity of the rheumatologic disease [11
]. This study was conducted in a clinical sample. In keeping with the idea that mental health is an important clinical issue for people with musculoskeletal conditions, Härter and others reported that rehabilitation patients with mental illness had diminished quality of life in several dimensions: general health, vitality, social and emotional role functioning and mental health [12
One clinical study used DSM-IIIR criteria to diagnose major depression in a sample with rheumatoid and osteoarthritis who had screened high on a symptom rating scale [13
], reporting a prevalence of 23% in rheumatoid arthritis and 10% in osteoarthritis. Finally, two clinical studies used structured diagnostic interviews to detect past episodes of major depression in clinical samples with rheumatoid arthritis. These studies reported lifetime prevalence estimates of 28.1% and 29.4% [14
], approximately two to three times higher than reported general population lifetime prevalence. An extremely high prevalence of psychiatric caseness was reported in another clinical study of patients with rheumatoid arthritis, 39% [16
]. However, because they used clinical samples, these studies may have overestimated prevalence by selecting particularly severely ill subjects.
Certain questions remain unanswered in the existing literature. First, although Wells and others [5
] found an association between substance use disorders and arthritis, this finding has subsequently apparently not been replicated. Second, none of the existing studies have examined the possible association between musculoskeletal conditions and mania orbi polar disorder. Finally, the association between various conditions and disability should be confirmed in view of the result reported by McWilliams, that both anxiety and depressive disorders can make an independent contribution to disability in people with these disorders [7
Some psychiatric epidemiological studies, including the Canadian Community Health Survey, Mental Health and Wellbeing (CCHS 1.2), have included high quality sampling and psychiatric diagnostic procedures. Unfortunately, suchstudies have typically incorporated limited information on conditions such as musculoskeletal disorders. For example, the CCHS 1.2 included only a single item asking each of its 36,984 respondents whether they had been diagnosed with "arthritis or rheumatism" by a health professional. Despite the lack of detail about rheumatologic status, such studies do provide an opportunity to describe the mental health status of people in the community who report having such disorders, and to answer questions that have not been addressed by the existing literature.