Introduction: In patients with clinically relevant periodic limb movements (PLM) and obstructive sleep apnea (OSA), symptoms and risk factors overlap [1]. However, a mechanistic link between both conditions is vague [2]. Previous studies focused mainly on associated comorbidities and their impact on PLM and OSA. Thus, little is known about PLM in healthy patients with suspected OSA.
Material and methods: Retrospective analysis of 112 patients (age: 44.5 ± 12.0 years, 14.3% female) with suspected OSA who underwent polysomnography. Patients with chronic diseases, recent infections, malignancies, or use of medication were excluded. Group comparisons were made based on OSA severity (apnea hypopnea index, AHI) or PLM index (PLMI). Kruskal-Wallis test, Dunn's multiple comparison test, or Mann Whitney test were used for statistics and Spearman"s coefficient was calculated.
Results: The PLMI and the total number of PLM increased with OSA severity. In addition, AHI was significantly higher in patients with PLMI >15/h (p<0.001). PLMI was significantly positive correlated with AHI (r=0.392, p<0.001). Patients with PLMI >15/h were significantly older (p<0.001). Body mass index (BMI) tended to be similar in patients with high PLMI and those without (p>0.05).
Conclusion/Discussion: In this healthy patient population, OSA severity was significantly associated with increased and likely clinically relevant PLM. Prospective studies with larger collectives should verify the presented results.

1 Haba-Rubio J et al. Prevalence and determinants of periodic limb movements in the general population. Annals of neurology. 2016 79(3), 464–474
2 Budhiraja R et al. Prevalence and correlates of periodic limb movements in OSA and the effect of CPAP therapy. Neurology. 2020 Apr 28;94(17):e1820-e1827

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