Sleep disturbance is associated with pain and depression in osteoarthritis of the knee, a new study reports, and baseline sleep disturbances predict increased disability and depression over time, even without increases in pain. The study was published online October 6 in Arthritis Care & Research.
"We know that pain causes sleep disturbance and ought to be on physicians' radar screens, but we're among the first to suggest having problems sleeping can cause you to experience functional decline," author Patricia Parmelee, PhD, from the Center for Mental Health and Aging at the University of Alabama, told Medscape Medical News. "When somebody complains of sleep problems, we need to take it seriously."
The researchers recruited 367 patients with physician-confirmed osteoarthritis of the knee from a variety of sources, including a geriatric clinic and announcements in news media, to include patients who had not sought specialty care. The participants completed a questionnaire by mail that included a checklist of 31 health conditions, subjective questions about health, the Center for Epidemiologic Studies Depression scale (minus a question about sleep quality to avoid confounding), pain measured by the Philadelphia Geriatric Center Pain Scale, and disability measured with the Arthritis Impact Measurement Scales, which included hand and arm function in addition to knee-related activities such as walking. The researchers assessed sleep with a single question about whether the patient had trouble sleeping.
One-year follow-up was available for 288 patients. Those lost to follow-up were more likely to be nonwhite and less educated and to have reported poorer subjective health, greater disability, and slightly greater pain.
Through regression analysis, baseline sleep disturbance was associated with pain (P < .02) and depression (P < .001), but not disability. "[S]leep disturbance exacerbated effects of pain on depression, such that depressive symptoms were greatest among those with both significant sleep problems and higher-than-average pain," the authors write.
Comparing baseline with 1-year follow-up data, sleep disturbance at baseline was linked with increased depression (P < .001) and disability (P < .005), but not pain.
Although the results are promising, says Dr Parmelee, further research is needed to pinpoint what is abnormal about patients' sleep. The questionnaire was not designed with sleep problems in mind, says Dr Parmelee, and the question used is "a very gross measure. We don't know if we're looking at an emotional response or a problem in objective sleep quality."
Kelli Allen, PhD, from the Division of General Internal Medicine at Duke University, Durham, North Carolina, who was not involved in the study, says that the results should encourage patients to talk to their healthcare provider about depression and sleep problems, rather than assuming they are an expected part of arthritis.
Strengths of the study, says Dr Allen, include the broad sample and the fact that 4 variables (sleep, pain, depression, and disability) were analyzed together. The longitudinal analysis is valuable to hint at causal relationships, although the mechanism is still unclear.
"For my money, the take-home message is we need to take osteoarthritis pain seriously, we need to take sleep disturbances seriously, and we need to take mood disturbances seriously," Dr Parmelee said. "Sleep and pain and mood and the ability to get about and do what you need and want to do are closely intertwined."
The next steps in research, she says, should focus on untangling those factors enough to know where to intervene. "Going to bed, is it better to take an antidepressant, a sleep-inducing medicine, or an [nonsteroidal anti-inflammatory drug]? Which would be the best approach to break up this cycle? We don't know that yet."
The research was supported by the National Institute of Mental Health. The authors and Dr. Allen have disclosed no relevant financial relationships.
Arthritis Care Res. Published online October 6, 2014. Abstract
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Cite this: Sleep Linked to Disability and Depression in Osteoarthritis - Medscape - Oct 10, 2014.
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