Sleep Characteristics In Patients With Comisa Compared To Osa And Insomnia

Study objectives: Obstructive sleep apnea (OSA) and insomnia frequently co-exist, which complicates treatment, for example resulting in a worse compliance to continuous positive airway pressure (CPAP) therapy. Early recognition of comorbid insomnia and sleep apnea (COMISA) is important since both sleep disorders can aggravate each other and COMISA is associated with increased risk of all-cause mortality. Research is needed to identify characteristics that can be used to recognize patients with COMISA, in order to optimize treatment approach from the start. The aim of this study is to investigate differences in sleep structure between patients with pure OSA, pure insomnia and COMISA. Methods: We obtained polysomnography data from 326 patients from the SOMNIA database. The group included patients with OSA (n=199), insomnia (n=47) and COMISA (n=80). We compared statistics related to sleep stages, awakenings and sleep disordered breathing (SDB) events between the three patient groups. Results: Wake after sleep onset (WASO) was significantly longer for the COMISA group compared to OSA (median, 83.3 vs 60.0 minutes, p<0.01). No significant differences were found in the total number of awakenings and the number of short (up to and including 2 minutes) and medium-length awakenings (2.5 up to and including 4.5 minutes). The number of long awakenings (five minutes or longer) and WASO containing only long awakenings were significantly higher for the COMISA group compared to OSA (median, 3.0 vs 2.0 awakenings, p<0.01, and median, 43.3 vs 25.5 minutes, p<0.001). The apnea-hypnopnea index (AHI) and the 4% oxygen desaturation index in COMISA were -as expected- higher compared to insomnia (median, 16.6 vs 6.8 events/hour, p<0.001, and median, 4.5 vs 0.8 desaturations/hour, p<0.001), but lower compared to OSA (median, 16.6 vs 21.6 events/hour, p=0.0136, and median, 4.5 vs 8.5 desaturations/hour, p=0.01). Conclusions: Patients with COMISA seem to present with a milder form of OSA, but nevertheless presented a more disturbed sleep structure, mainly characterized by prolonged awakenings. Further research is needed into these sleep characteristics that may lead to a better understanding of the mechanisms involved, earlier diagnosis and better treatment strategies.