ABSTRACT
Objective:To investigate the correlation between 25 hydroxyvitamin D[25 (OH) D] level and sleep monitoring index in patients with severe altitude obstructive sleep apnea hypopnea syndrome (OSAHS).Methods:Sixty-six patients with severe OSAHS (AHI≥30 times/hour) diagnosed by apnea hypopnea index (AHI) who had lived at high altitude (1 800-4 193 m) for≥1 year were included in the experimental group. The patients underwent polysomnography monitoring in Sleep Medicine Center of Qinghai Red Cross Hospital from June to December 2021. In addition, healthy volunteers matched the experimental group by gender, age, ethnicity and living altitude during the same period were selected for polysomnography monitoring. Finally, 48 healthy volunteers with AHI<5 times/hour were included as the control group. 25(OH)D level and its deficiency were compared between the two groups. The experimental group was further divided into severe deficiency group [25(OH)D≤10 μg/L], the deficiency group [10 μg/L<25(OH)D≤20 μg/L] and the non-deficiency group [25(OH)D>20 μg/L] according to 25(OH)D level, and the differences of sleep parameters among the three groups were compared. Correlation analysis and multifactor linear regression analysis were performed on the factors that may affect the level of 25(OH)D in patients with severe OSAHS.Results:A total of 114 adults living on the plateau for at least one year were enrolled, including 66 in the experimental group and 48 in the control group. 25(OH)D deficiency (≤30 μg/L) was found in all the individuals included in the experimental group and the control group, and the 25(OH)D level of the two groups was [(13.13±4.05) vs (13.68±4.60) μg/L, P=0.507] and there was no significant difference in deficiency degree (all P>0.05). Within the experimental group, rapid eye movement (REM) sleep time and proportion (REM%) and sleep awakening time of 25(OH)D non-deficiency group, were significantly lower than those in severe deficiency group (all P<0.05), and sleep efficiency in 25(OH)D non-deficiency group was significantly higher than that in severe deficiency group and deficiency group (all P<0.05). Spearman correlation analysis showed that the level of 25 (OH) D in experimental group were positively correlated with serum calcium ion level ( r=0.293, P=0.017) and sleep efficiency ( r=0.309, P=0.011), and were negatively correlated with age ( r=-0.298, P=0.015), REM sleep time ( r=-0.401, P=0.001), REM% ( r=-0.421, P<0.001) and awakening time ( r=-0.362, P=0.003). Multifactor linear regression analysis suggested that serum calcium, REM sleep time and history of hypertension were the predictors of 25(OH)D level in severe OSAHS at high altitude. Conclusions:There is a correlation between sleep monitoring indexes and serum 25(OH)D level in patients with severe OSAHS at high altitude. The longer the REM sleep time, the lower the 25(OH)D level. Meanwhile, there is a certain relationship between co-morbidity hypertension and 25(OH)D level in patients with severe OSAHS at high altitude.