We examined the association between sleep and odds of developing knee pain, and whether this relationship varied by status of widespread pain (WSP).
At the 60-month visit of the Multicenter Osteoarthritis Study, sleep quality and restless sleep were each assessed by using a single item from two validated questionnaires; each sleep measure was categorized into three levels with poor/most restless sleep as the reference. WSP was defined as pain above and below the waist on both sides of the body and axially using a standard homunculus, based on the American College of Rheumatology criteria. Outcomes from 60-84 months included 1) knee pain worsening (KPW, defined as minimal clinically important difference in WOMAC pain], 2) prevalent and 3) incident consistent frequent knee pain. We applied Generalized Estimating Equations in multivariable logistic regression models.
We studied 2329 participants (4658 knees) [67.9y, BMI: 30.9]. We found that WSP modified the relationship between sleep quality and KPW (p<0.01 for interaction). Among persons with WSP, odds ratio (95% confidence interval) for KPW was 0.54 (0.35, 0.78) for those with very good sleep quality (p-trend<0.001); additionally, we found the strongest association of sleep quality in persons with >8 painful joint sites (p- trend<0.01), but not in those with ≤ 2 painful joint sites. Similar results were observed using restless sleep, in the presence of WSP. Cross-sectional relationship was suggested significant between sleep and prevalence of consistent frequent knee pain.
Better sleep was related to less knee pain worsening with coexisting widespread pain.