A Study Of Bone Metabolism In Patients With Obstructive Sleep Apnea

Objective:To compare the difference between non-elderly obstructive sleep apnea(OSA)patients of different severity and normal controls in venous bone metabolic markers and high-resolution peripheral quantitative computed tomography(HR-pQCT)parameters,and identify the link between OSA and osteoporosis and explore the underlying mechanisms.Methods:Non-elderly males who visited the Sleep and Respiratory Center in our hospital from August 2017 to February 2019 were continuously recruied.Medical history were collected,and Epworth sleep scale(ESS)scores were completed.Polysomnography(PSG)was used to evaluate norcturnal sleep and respiratory conditions.Populations meeting the OSA diagnostic criteria were classified as the case group,and then divided into mild,medium,and severe groups according to the severity.The control group 1 was selected from those who did not meet the OSA diagnostic criteria.The control group 2 were selected from male healthy people who matched with severe ones in gender,age and body mass index(BMI).Those with high risk of OSA were excluded by Berlin questionnaire.Peripheral venous blood samples were collected from subjects of case groups and control group 1,to detect the following indicators:1.Metabolic indicators,including blood glucose(BG),total cholesterol(TC),triglycerides(TG),and high-density lipoprotein cholesterol(HDL-C);2.Inflammatory indicators,including interleuki(IL)-6,Tumor necrosis factor(TNF)-a,Erythrocyte sedimentation rate(ESR)and hypersensitive C-reactive protein(HsCRP);3.Bone metabolism indicators,including calcium(Ca),phosphorus(P),alkaline phosphatase(ALP),total 25 Total 25-hydroxy vitamin D(T-250HD)and(3-C-terminal telopeptide of type I collagen(β-CTX).HR-pQCT was used to measure the non-dominant lateral radius and tibia.The OSA patients with different severity and non-OSA populations were compared in bone metabolism indicators,bone geometry,bone density,and bone microstructure,aiming to find a link between OSA and osteoporosis,and to explore the risk factors for OSA affecting bone.Results:(1)A total of 90 subjects were enrolled in this study with PSG.The number of patients in mild,moderate,severe,and non-OSA control groups were 21,18,34,and 10,respectively.The overall mean age was(47.13±5.85)years,and the mean body mass index(BMI)was(25.66±2.09)kg/m2.1.The BMI of the severe OSA group patients was significantly higher than that of the control group 1 and mild OSA group(P=0.036 and 0.021).The proportion of OSA patients with dyslipidemia was significantly higher than that of the control group 1(Χ2=10.033,P=0.018).There was no significantly statistical difference between these groups in age,blood pressure level,other body type indicators(including neck circumference,waist circumference,hip circumference and waist-to-hip ratio),the proportion of other comorbidities and bad habits,ESS score,proportion of sleep in each period,and sleep efficiency.2.In terms of blood results,the TG level of severe OSA patients was significantly higher than that of the control group 1(P=0.009),and the BG level was significantly higher than that of the mild OSA group(P=0.006).There was no significant difference on other metabolic,inflammatory and bone metabolic indicators(P≥0.05).3.In terms of HRCT,there was no significant difference in the parameters of the radius between the four groups(P≥0.05).For tibia,as a geometric parameter,cortical area(Ct.Ar)of the severe OSA group was significantly higher than that of the mild and moderate ones(P=0.06 and P=0.048).As bone mineral density parameters,there were significant differences between the four groups in total volumetric bone mineral density(Tt.vBMD)and meta trabecular vBMD(Tb.Meta.vBMD)(F=2.990,P=0.035;F=3.696,P=0.015).The mean values of OSA groups were lower than that of the control group 1.As bone microstructure patameters,there were significant differences between the four groups in trabecular thickness(Tb.Th)and cortical thickness(Ct.Th)(F=7.060,P= 0.000;F=4.959,P=0.003).The mean values of OS A groups were lower than that of the control group 1.4.Correlation analysis and regression analysis showed that parameters of HR-pQCT were mostly correlated with age,body size indexes(including BMI,neck circumference,etc)and comorbidity parameters(P<0.05).There was no significant correlation between the indicators of the severity of OSA[including apnea hypopnea index(AHI)and multiple nocturnal oxygen indicators],and the various bone indicators P≥0.05).In addition,sleep efficiency showed a correlation with multiple indicators of the radius(P<0.05).(2)A total of 34 subjects were included in control group 2.The mean age was(46.82±6.80)years,and the mean BMI was(26.00±1.82)kg/m2.There was no significant difference in age and BMI between severe OSA groups and control group 2(t=-0.212,P=0.833;P=1.551,P=0.126).HR-pQCT results showed that there was no statistically significant difference in bone geometric,volumetric bone mineral density and bone microstructure parameters between the two groups after the regulation of age and BMI(P≥0.05).Conclusions:This study showed that in non-elderly male populations,OS A patients intend to have lower bone mineral density and lower Tb.Th,Ct.Th than normal populations.Bone metabolism is mainly affected by age and body size.The effect of OSA on bone mass is presumed to be related with body size characteristics,metabolic complacations caused by OSA,and changes in sleep efficiency.There is no clear correlation between osteoporosis and the severity of OSA itself.