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 2 validated questionnaires. Each sleep measure was categorized into 3 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; 67.9 yrs, body mass index 30.9]. We found that WSP modified the relationship between sleep quality and KPW (p = 0.002 for interaction). Among persons with WSP, OR (95% CI) for KPW was 0.53 (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. The cross-sectional relationship between sleep and prevalence of consistent frequent knee pain was significant.
Better sleep was related to less KPW with coexisting widespread pain.