Reduced sleep quality is highly prevalent and associated with physical function and cardiorespiratory fitness in patients with axial spondyloarthritis: a cross-sectional study

Abstract

Objectives

To assess sleep quality, and its associations with physical function, cardiorespiratory fitness, and spinal mobility, in axial spondyloarthritis (axSpA) patients.

Method

Baseline data from the Exercise for Spondyloarthritis trial were used. Assessments included [Pittsburgh Sleep Quality Index (PSQI), 0–21, 21 = worst], performance-based physical function [Ankylosing Spondylitis Performance Index (ASPI), seconds, higher = worse], patient-reported physical function [Bath Ankylosing Spondylitis Functional Index (BASFI), 0–10, 10 = worst], cardiorespiratory fitness [peak oxygen uptake ($\mathrm{V}$O_2peak), mL/kg/min, lower = worse], and spinal mobility [Bath Ankylosing Spondylitis Metrology Index (BASMI), 0–10, 10 = worst]. Associations were examined in separate models using multiple linear regression.

Results

Ninety-nine patients with axSpA were included, 53% female, mean age 46 years, and 72% with high disease activity (ASDAS-C-reactive protein ≥ 2.1), of whom 84 (85%) had reduced sleep quality. Sleep disturbance was most frequently reported (65%), followed by poor subjective sleep quality (53%), daytime dysfunction (41%), and increased sleep latency (41%). Positive associations were observed between PSQI and ASPI [β = 0.10, 95% confidence interval (CI) 0.01, 0.19] and PSQI and BASFI (β = 0.85, 95% CI 0.51, 1.20), and there was an inverse association between PSQI and $\mathrm{V}$O_2peak (β = −0.14, 95% CI −0.27, −0.01), adjusted for age and sex. There was no association between PSQI and BASMI.

Conclusion

Reduced sleep quality was common in axSpA patients with moderate to high disease activity. Better sleep quality was associated with better physical function and higher cardiorespiratory fitness. There was no association between sleep quality and spinal mobility.

Trial registration

ClinicalTrials.gov NCT02356874

Acknowledgements

The authors gratefully thank all participating patients, study personnel, and patient research partners.

Disclosure statement

No potential conflict of interest was reported by the authors.

Data availability statement

The data underlying this article are available from the corresponding author upon reasonable request https://www.diakonhjemmetsykehus.no/.

Additional information

Funding

This study was funded by the Norwegian Fund for Post-Graduate Training in Physiotherapy and the Research Council of Norway [grant number 328657].