By John Gever, Senior Editor, MedPage Today
Published: August 07, 2009
Reviewed by Zalman S. Agus, MD; Emeritus Professor
University of Pennsylvania School of Medicine
Depression is an independent risk factor for some rheumatoid arthritis symptoms, even when it's the patient's spouse who is depressed, researchers found.
That's the conclusion of two separate studies published in the August 15 issue of Arthritis & Rheumatism.
One study, by Masayo Kojima, MD, PhD, of Nagoya City University in Nagoya, Japan, and colleagues, determined that depression severity was correlated with C-reactive protein (CRP) levels in rheumatoid arthritis patients -- and that both factors were independently predictive of pain.
In the other study, Anita DeLongis, PhD, of the University of British Columbia in Vancouver, and colleagues found that spousal depression predicted a worse one-year disease course for patients.
The findings extend earlier research indicating that, as DeLongis and colleagues put it, "The emotional well-being of persons with rheumatoid arthritis [plays] a critical role in disease course and disability."
Depression is especially common among patients with rheumatoid arthritis. However, evidence increasingly suggests that depression is not just a consequence of arthritis pain and disability, but an independent contributor to the disease.
For example, researchers previously found that a single depressive episode predicts worse arthritis-related pain later.
Kojima and colleagues enlisted 218 patients with established rheumatoid arthritis (mean disease duration 12 years) to fill out questionnaires that included items from the Beck Depression Inventory II, as well as a visual analog scale for pain.
They found that depression scores correlated significantly with CRP levels (r=0.46, P<0.001). Moreover, depression scores were significantly associated with pain scores (standardized beta=0.35, P<0.001) after adjusting for clinical covariates such as disability and global disease severity.
Likewise, CRP levels were significantly correlated with pain scores (standardized beta=0.35, P<0.001) with adjustments for clinical covariates.
Kojima and colleagues found that depression and CRP levels were additive in predicting pain. Patients in the highest tertiles for both depression scores and CRP had an odds ratio of nearly 60 for reporting severe pain, relative to those in the lowest tertiles on both.
For patients in the highest tertile for depression and the lowest for CRP, or the reverse, the odds ratio for reporting severe pain was closer to 20.
The researchers said it was difficult to separate the contributions from depression and inflammation (as reflected by CRP levels). Still, they suggested their data supported the idea that depression in rheumatoid arthritis is more than just a psychological reaction to the somatic symptoms.
"A clinical approach that takes into account both the body and the mind could have benefits and could enable optimal pain control," they wrote.
DeLongis and colleagues found that even in patients who are not themselves depressed, arthritis symptoms are frequently worse when the patient's spouse is depressed.
They studied 133 married rheumatoid arthritis patients and their spouses over a one-year period. The patients underwent standard disease severity assessments, including the Rheumatoid Arthritis Disease Activity Index and the Disabilities of the Arm, Shoulder, and Hand scale.
Both partners completed the Center for Epidemiologic Studies Depression Scale at baseline and again at the one-year follow-up.
They found that spousal depression symptoms "made a unique and significant contribution to the prediction of the [patient's] disease activity at follow-up," after adjusting for sex and baseline levels of disease activity and patient's own depressive symptoms. They quantified the relationship with a beta value of 0.18, t(122)=2.39, P<0.05) in a hierarchical multiple regression model.
The researchers found a similar relationship for disability scores, with beta=0.16, t(121)=2.91, P<0.01).
A mediational test showed that the patient's own depression was also a significant predictor of disability and disease activity at follow-up. But patients' depression was not significantly driven by spousal depression, the analysis indicated.
DeLongis and colleagues said the findings fit in with earlier research suggesting that social relationships influence the course of rheumatoid arthritis, for good or ill.
They said it was "reasonable to expect, given the findings on the role of mood in rheumatoid arthritis disease course, that spouse mood is one path through which close relationships affect [arthritis] disease course."
The mechanism remains unclear, they added. "Whether depressed spouses are unable or unwilling to provide much needed support to the [patient], or whether their depressed mood affects [patient] outcomes in some other way, is yet to be determined."
The researchers said their findings were limited by sample homogeneity, in that most of their participants were well-educated, white Canadians. They also noted that since most of their patients were women -- as are rheumatoid arthritis patients in general -- "the role of patient and the role of wife tend to be confounded in couples research on rheumatoid arthritis."
Kojima and colleagues identified limitations to their study, including a sample drawn from patients at a university clinic, use of self-reports to evaluate depression and pain, and lack of data on other factors such as adiposity that might have influenced outcomes.
Neither study assessed radiographic progression in addition to subjective assessments of disease severity.
The Japanese study was funded by the Japan Society for the Promotion of Science.
The Canadian study was supported by the Michael Smith Foundation for Health Research, the Canadian Institutes of Health Research, the Canadian Arthritis Network, a Pfizer Fellowship in Arthritis Research, and the Social Science and Humanities Research Council of Canada.
No potential conflicts of interest were reported by either group.
http://www.medpagetoday.com/Rheumatology/Arthritis/15430
You don't stop laughing because you grow old. You grow old because you stop laughing.
-- Michael Pritchard
Note: I am not a doctor or nurse. I was a counselor for 30 years. Information given is my own advice or I have listed the source for my information.
