[Relationship between sleep quality and nocturnal pain in ankylosing spondylitis]

To evaluate the relationship between sleep quality and nocturnal pain in ankylosing spondylitis (AS) patients.

A total of 157 AS patients were recruited. Pittsburgh sleeping quality index (PSQI) and visual analogue scale (VAS) were used to assess sleep quality and nocturnal pain respectively. Disease activity was assessed by Bath ankylosing spondylitis disease activity index (BASDAI), C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR).

The mean PSQI and nocturnal pain score was 6.6 ± 3.6 and 3.7 ± 3.0 respectively. Fifty-five of them had poor sleep. Quality of sleep was positively correlated with nocturnal pain (P < 0.01). Elevated ESR/CRP was found in 47.1% (74/157) of them. Patients with elevated ESR/CRP had significantly a higher level of BASDAI than those with normal ESR/CRP (P < 0.01). Logistic regression analysis revealed that nocturnal pain was most powerful risk factor of sleep disturbances (P < 0.05). In hierarchical multiple regression analysis, the quality of sleep variable contributed significantly to the variance in nocturnal pain scores, adding an additional 18.2% to the overall R-square beyond that accounted by demographic and disease-related variables (inclusion of ESR and CRP) (R(2) = 0.175).

Sleep quality has close relationship with nocturnal pain. And sleep disturbances should be considered in the management of AS.