Sleep quality in individuals with chronic low back pain and central sensitization.

Background and purpose: Sleep problems are common in individuals with chronic low back pain (CLBP). Central sensitization (CS) is present in a subgroup of individuals with CLBP. However, our knowledge about whether sleep quality varies between the subgroups of CLBP is limited. Therefore, we sought to examine whether the subgroup of CLBP with CS has poorer sleep quality than the subgroup without CS.

Methods: 2011 Fibromyalgia Survey (2011 FM survey) was used as a surrogate measure of CS to divide the CLBP participants into two subgroups: CLBP with CS and CLBP without CS. We also created a CS index comprising a set of quantitative sensory testing measures (i.e., pressure pain thresholds, conditioned pain modulation) to evaluate pain sensitivity. Sleep quality was assessed with Pittsburgh Sleep Quality Index (PSQI). Group differences about PSQI and CS index and associations between sleep quality and CS across the groups were analyzed.

Results: We included 60 participants with CLBP and 23 healthy controls (HCs). Overall, 80% of the participants with CLBP presented with poor sleep quality. Participants with CLBP with CS showed significantly higher PSQI scores (poorer sleep) than participants with CLBP without CS and HCs (p < 0.05). Both the 2011 FM survey and CS index were significantly correlated with sleep quality (r = 0.5870, p < 0.001 and r = -0.264, p = 0.04). Logistic regression models revealed that the FM status (odds ratio (OR) = 6.00, p = 0.02 [95% confidence interval: 1.31-42.1]), but not the CS index (OR = 1.11, p = 0.79 [95% CI: 0.48-2.71]) was associated with PSQI. After adjusting covariates, the results remained similar but became non-significant for the FM status.

Discussion: We found that sleep problems were more common and severe in those who exhibited signs of CS. Thus, clinicians may consider using 2011 FM survey to identify those with CS and co-existing sleep problems.