Sleep, Pain Catastrophizing, and Central Sensitization in Knee Osteoarthritis Patients With and Without Insomnia

Abstract

Objective: Osteoarthritis (OA), a chronic degenerative joint disorder, is characterized by joint pain. Emerging research demonstrates that a significant number of patients evidence central sensitization (CS), a hyperexcitability in nociceptive pathways, which is known to amplify and maintain clinical pain. The clinical correlates of CS in OA, however, are poorly understood. Insomnia is prevalent in older adults with OA, and recent experiments suggest associations between poor sleep and measures of CS. Catastrophizing, a potent predictor of pain outcomes, has also been associated with CS, but few studies have investigated possible interactions between catastrophizing, sleep, and CS.

Methods: We conducted a case-control study of 4 well-characterized groups of adults with insomnia and/or knee OA. A total of 208 participants completed multimodal sleep assessments (questionnaire, diary, actigraphy, and polysomnography) and extensive evaluation of pain using clinical measures and quantitative sensory testing to evaluate associations between CS, catastrophizing, and insomnia. Descriptive characterization of each measure is presented, with specific focus on sleep efficiency and CS.

Results: The knee OA-insomnia group demonstrated the greatest degree of CS compared to controls. In the overall sample, we found that catastrophizing moderated the relationship between sleep efficiency and CS. Specifically those with low sleep efficiency and high catastrophizing scores reported increased levels of CS. In addition, CS was significantly associated with increased clinical pain.

Conclusion: These findings highlight the importance of assessing sleep efficiency, CS, and catastrophizing in chronic pain patients and have important clinical implications for treatment planning.

Trial registration: ClinicalTrials.gov NCT00592449.

Conflict of interest statement

Conflicts: The authors have no conflicts of interest to report.

© 2015, American College of Rheumatology.

Figures

Figure 1

Z-scored means and standard error for laboratory pain methods displayed by group. Measures denoted with ‡ were reversed (multiplied by −1) in order to keep directionality consistent. *p

Figure 2

Interaction of Catastrophizing and Sleep Efficiency predicting Central Sensitization.

Figure 3

Conditional effect of Sleep Efficiency on Central Sensitization across values of Catastrophizing. The region of significance lies where the confidence interval does not include 0. Thus, sleep efficiency is associated with central sensitization when catastrophizing is higher than 7.4