Obstructive sleep apnea is associated with preserved bone mineral density in healthy elderly subjects

Body mass index mediates the association between plasma lipid concentrations and the prevalence of obstructive sleep apnea among US adults: a cross-sectional study

Background

The association between obstructive sleep apnea (OSA) and plasma lipid concentrations is not consistent. This study aimed to investigate the association of plasma lipid concentrations with the prevalence of OSA among US adults, with an additional examination of the mediating effect of body mass index (BMI).

Methods

This cross-sectional study included 8,086 individuals who participated in the National Health and Nutrition Examination Survey (NHANES), conducted from 2005 to 2008 and 2015-2018. Multivariable logistic regression analysis was conducted to compute the odds ratios (ORs) and 95% confidence intervals (CIs) for the association between plasma lipid concentrations and the prevalence of OSA. Additionally, subgroup analysis was used to explore the potential interactions. Generalized additive models (GAM) were constructed to evaluate the nonlinear relationships between lipid concentrations and OSA. Furthermore, mediation analysis was performed to assess the potential mediating role of BMI.

Results

In the fully adjusted model, when comparing the lowest quartile, the ORs for the prevalence of OSA among participants in the highest quartile were 1.367 (95% CI, 1.107-1.688) for triglyceride and 1.212 (95% CI, 1.004-1.462) for low-density lipoprotein cholesterol (LDL-C). However, total cholesterol (TC) and high-density lipoprotein cholesterol (HDL-C) were not associated with OSA. Notably, the relationship between triglyceride and OSA differed in the subgroups of gender, race, and body mass index (BMI) (P for interaction <0.05). Furthermore, we discovered an inverted U-shaped association between triglyceride and OSA (inflection point: 0.813 mmol/L). Causal mediation analysis revealed that BMI significantly mediated the relationship between triglyceride and the prevalence of OSA.

Conclusions

This study revealed that an elevated level of triglyceride increased the prevalence of OSA, and this effect was potentially mediated through BMI. Lowering triglyceride concentration may help to reduce the prevalence of OSA.

Impact of the visceral adipose tissue on bone quality in patients with untreated mild-to-severe obstructive sleep apnea

Obstructive sleep apnea (OSA) predominantly affects patients who are obese and causes systemic organ damage. Little is known about the relationship between fat distribution and bone impairment in these patients. We aimed to evaluate the impact of the visceral adipose tissue (VAT) on the bone quality of patients with OSA. In our prospective study, 49 untreated patients with mild-to-severe OSA underwent dual-energy X-ray absorptiometry. Polygraphy data were also collected. According to the recent reference values for European adults, patients were divided by the sex-related threshold of the VAT index into two categories: VAT index within limits (normal VAT [nVAT]) and increased VAT (iVAT). In all, 63% of the patients were in the iVAT category. Compared to patients with nVAT, those with iVAT had a higher prevalence of arterial hypertension (52% versus 22%) and diabetes (32% versus 6%), and higher values of mean nocturnal desaturation. Patients with iVAT had, in comparison to those with nVAT, lower values of the lumbar spine trabecular bone score (TBS; mean 1.24 versus 1.39; p < 0.001), TBS T-score (mean -1.82 versus -0.52; p < 0.001) and TBS Z-score (mean -0.35 versus 0.75; p = 0.002). Moreover, a close association was present between the VAT index and TBS lumbar spine L1-L4 (r2 linear 0.573; p < 0.001), and altered values of the TBS Z-score were associated with the severity of vertebral fractures. Finally, in a linear regression-adjusted model, the VAT index predicted TBS lumbar spine L1-L4 (β -0.323; p < 0.001). In patients with OSA VAT impacts bone quality. In these patients, the role of VAT as a metabolically active tissue should be considered.

The association between obstructive sleep apnea and osteoporosis: A systematic review and meta-analysis

Obstructive sleep apnea (OSA) is a sleep disorder with well-known metabolic consequences. The relationship between OSA and bone health, especially osteoporosis, remains poorly understood. Given that both OSA and osteoporosis are highly prevalent chronic conditions with significant public health implications, this study aims to investigate the association of OSA with bone health and osteoporosis. A systematic search of PubMed, Embase and Cochrane Library was conducted from inception to November 22, 2022. Fifteen studies comprising 158,273 individuals were included. The presence of OSA correlated negatively with bone mineral density on meta-analysis (pooled correlation = -0.30; 95 % CI, -0.42 to -0.17; N = 8). Individuals with OSA had poorer bone mineral density scores (mean difference = -0.58, 95 % CI, -1.15 to -0.01; N = 8), and significantly higher risk of developing osteoporosis (adjusted odds ratio = 2.18; 95 % CI, 1.14 to 4.16; N = 4). Notably, both body mass index (BMI) and age were not significant effect modulators in the correlation of OSA and bone density. These findings suggest that OSA is associated with diminished bone health, and it is severity-dependent. Further studies are required to determine if treatment of OSA may have the potential to mitigate these risks.

Association of obstructive sleep apnea with bone metabolism in older adults: a hospital-based study

PURPOSE

Obstructive sleep apnea (OSA) significantly affects patients' quality of life; however, the mechanisms, such as its effects on bone mineral density (BMD) and bone turnover marker (BTM) expression, remain unclear. In this study, we investigated the relationships among OSA, BMD, and (BTMs) in older adults.

METHODS

This retrospective study enrolled 260 participants (114 women; 44.5%). Data of an established system (Alice NightOne) were used to diagnose OSA and analyze nocturnal hypoxia. Participants were divided into four groups according to respiratory event index (REI) (control, < 5 times/hour; mild OSA, 5-15 times/hour; moderate OSA 15-30 times/hour; severe OSA ≥ 30 times/hour). BMD were mesured by dual-energy x-ray absorptiometry. BTMs including bone specific alkaline phosphatase (BALP), tartrate-resistant acid phosphatase 5b (TRAP-5b) were collected.

RESULTS

Patients with OSA had higher BMD at first lumbar vertebra, left and right femur than those without (all p < 0.05). REI was positively correlated with BMD at the first lumbar vertebra (r = 0.181, p = 0.006), left femur (r = 0.160, p = 0.014), and right femur (r = 0.243, p < 0.001). In participants with body mass index (BMI) of 18-24 kg/m2 (N = 96), the correlation between REI and BMD at the left femur(r = 0.251, p = 0.019) and right femur (r = 0.258, p = 0.018) remained. Multiple regression analysis showed that OSA was significantly associated with osteoporosis (p = 0.034, 95% confidence interval, 0.092-0.100, odds ratio, 0.092). MSaO2 was positively correlated with TRAP5b (r = 0.560, p = 0.007). In participants with a BMI of ≥ 24 kg/m2(N = 164), MSaO2 was negatively correlated with BALP (r = -0.331, p = 0.034). No significant association between REI and BMD was observed.

CONCLUSIONS

OSA and hypoxia were associated with higher BMD in older adults in BMI of 18-24 kg/m2 but not in participants with a BMI of ≥ 24 kg/m2. This study suggests a negative association between OSA and osteoporosis in non-overweight and obese population. BMI played an important role. The study's findings could help exploration mechanisms of osteoporosis and promoting its treatment.

Sleep characteristics and parameters of bone turnover and strength in the adult population: results from the Study of Health in Pomerania-TREND

Poor sleep quality or sleep deprivation may be related to decreased bone mineral density. We aimed to assess whether associations of sleep characteristics and bone turnover or strength are present in adults from the general population and whether these are independent of common risk factors such as sex, age, and obesity. A total of 1037 participants from the Study of Health in Pomerania-TREND underwent laboratory-based polysomnography and quantitative ultrasound measurements at the heel. Of these participants, 804 completed standardised questionnaires to assess daytime sleepiness, insomnia, and sleep quality. Serum concentrations of two bone turnover markers, intact amino-terminal propeptide of type 1 procollagen (P1NP) and carboxy-terminal telopeptide of type 1 collagen (CTX) were measured. Cross-sectional associations of polysomnography variables (total sleep time, sleep efficiency, time spent wake after sleep onset, oxygen desaturation index, apnea-hypopnea index, and obstructive sleep apnea [OSA]), as well as sleep questionnaire scores with the bone turnover markers and the ultrasound-based stiffness index were assessed in linear regression models. In adjusted models, higher insomnia scores and lower sleep quality scores were related to a higher bone turnover in women but not in men. However, associations between polysomnography variables or questionnaire scores and the stiffness index were absent. Our study provides limited evidence for relationships between sleep characteristics and bone turnover and strength independent of common risk factors for OSA and osteoporosis. Nevertheless, women reporting poor sleep or insomnia in combination with risk factors for osteoporosis might benefit from an evaluation of bone health.

Early bone loss in patients with obstructive sleep apnea: a cross-sectional study

BACKGROUND

Obstructive sleep apnea (OSA) and osteoporosis are both prevalent diseases with shared pathophysiological mechanisms and risk factors. However, the association between the two diseases is seldom studied. This study aimed to identify the link between OSA and bone metabolism.

METHODS

Male participants aged 30-59-years who visited the sleep clinic were continuously recruited. Polysomnography was used to evaluate sleep and respiratory conditions. Blood samples were collected to detect metabolic, inflammatory and bone turnover indicators. High-resolution peripheral quantitative computer tomography was used to measure the non-dominant lateral radius and tibia.

RESULTS

Ninety subjects were recruited. The cortical area (Ct.Ar) of tibia of the severe OSA group was significantly higher than that of the mild and moderate OSA groups (P = 0.06 and P = 0.048). There were significant differences between the four groups in terms of total volumetric bone mineral density (vBMD) (F = 2.990, P = 0.035), meta trabecular vBMD (F = 3.696, P = 0.015), trabecular thickness (Tb.Th) (F = 7.060, P = 0.000) and cortical thickness (Ct.Th) (F = 4.959, P = 0.003). The mean values of the OSA groups were lower than control group. Hypopnea index and percentage of total sleep time with SpO2 < 90% were both positively correlated with alkaline phosphatase (R = 0.213, P = 0.044; R = 0.212, P = 0.045). Sleep efficiency was correlated with multiple indicators of the radius.

CONCLUSIONS

In non-elderly male populations, OSA patients tended to have lower vBMD, Tb.Th and Ct.Th than non-OSA patients. The negative effect of OSA may mainly affect the osteogenesis process, and is presumed to be related to sleep-related hypoxemia and sleep efficiency.

Association between obstructive sleep apnea and low bone mass in adults: a systematic review and meta-analysis

Introduction

This study aimed to synthesize existing evidence on the potential association between obstructive sleep apnea (OSA) and low bone mass in adults.

Methods

Electronic searches of four main databases were performed. The inclusion criteria consisted of observational studies investigating the relationship between OSA and bone mass, osteoporosis, fractures, or bone metabolism markers in adult population. Bone mineral density (BMD) and T score of lumbar and femur neck, incidence of osteoporosis and fractures, bone metabolism marker levels were extracted as primary outcomes.

Results

Among the 693 relevant publications, 10 studies consisting of 158,427 participants met with the inclusion and exclusion criteria. Meta-analysis showed a significant lower BMD of lumbar (mean difference (MD) = - 0.03; 95% CI - 0.05, - 0.01; I2 = 46%), femur neck (MD = - 0.06; 95% CI - 0.12, 0.00; I2 = 71%), and a significant lower T score of lumbar (MD = - 0.42; 95% CI - 0.79, - 0.05; I2 = 63%) in the OSA group. The results suggested that both male (odds ratio (OR) = 2.03; 95% CI 1.23, 3.35; I2 = 38%) and female (OR = 2.56; 95% CI 1.96, 3.34; I2 = 0%) had higher risk of osteoporosis in the OSA group. Besides, meta-analysis also showed that bone-specific alkaline phosphatase was significantly lower in OSA patients (MD = - 1.90; 95% CI - 3.48, - 0.32; I2 = 48%).

Conclusions

A potential association between OSA and lower bone mass in adults is preliminarily proved. It also seems plausible that both male and female with OSA have a higher risk of osteoporosis.

Supplementary Information

The online version contains supplementary material available at 10.1007/s41105-023-00481-1.

Association between obstructive sleep apnea syndrome and bone mineral density in adult orthodontic populations

OBJECTIVE

To determine the association between obstructive sleep apnea syndrome (OSAS) and predicted bone mineral density (BMD) in adults presenting for orthodontic treatment.

METHODS

This retrospective cross-sectional study included 38 adults divided into OSAS and non-OSAS groups. Using pre-treatment CBCT images, radiographic density (RD) of left and right lateral regions of the 1st cervical vertebrae and dens of the 2nd cervical vertebrae were measured as an indicator for BMD.

RESULTS

When controlling for age, sex, and BMI, the mean RD was significantly lower in the OSAS group compared to the non-OSAS group (left CV1: 36.69 ± 84.50 vs. 81.67 ± 93.25 Hounsfield Units [HU], respectively, p = 0.031; right CV1: 30.59 ± 81.18 vs. 74.26 ± 91.81 HU, p = 0.045; dens: 159.25 ± 115.96 vs. 223.94 ± 106.09 HU, p = 0.038).

CONCLUSION

Adults with OSAS have lower values for predicted BMD than those without OSAS.

Assessment of bone mineral density and bone metabolism in young men with obstructive sleep apnea: a cross-sectional study

BACKGROUND

Hypoxia in obstructive sleep apnea (OSA) patients during sleep may have an effect on bone metabolism. Few data regarding evaluation of bone metabolism in young individuals diagnosed with OSA. In this study, we aim to identify the association between bone mineral density and OSA in young men (≤ 40 years old of age).

METHODS

Consecutive male subjects who underwent polysomnography were enrolled. Serum calcium, 25-hydroxyvitamin-D3, β-isomerized form C-terminal telopeptide of type I collagen, osteocalcin and procollagen type 1 N-propeptide were measured in all participants, and bone mineral density (BMD) at lumbar spine (L1-L4), femoral neck and hip total were determined by dual energy X-ray absorption (DXA).

RESULTS

The population consisted of 85 subjects (mean age 35.53 years). The BMD at lumbar spine (L1-L4) in moderate OSA patients was higher than control and severe OSA group significantly (p = 0.036). After adjustment for confounding factors, stepwise multiple linear regression analyses showed LaSO₂ (β = 0.340, p = 0.008) as an independent explanatory variable for Lumbar L1-L4 BMD, LaSO₂ (β = 0.304, p = 0.037), BMI (β = 0.393, p = 0.008) for femur neck BMD and BMI (β = 0.720, p = 0.002) for hip total BMD.

CONCLUSIONS

Our finding indicated that there was a relationship between OSA and bone metabolism in younger men, and moderate OSA-related hypoxia positively related with BMD. This study also showed that different degrees of recurrent hypoxia had different effects on bone metabolism, a finding that required further investigation.

Bone mineral density alteration in obstructive sleep apnea by derived computed tomography screening

The association between obstructive sleep apnea (OSA) and bone mineral density (BMD) is poorly elucidated and has contradictory findings. Abdominal computed tomography (CT) for other indications can provide a valuable opportunity for osteoporosis screening. Thus, we retrospectively explored the association between OSA and BMD by examining abdominal CT vertebrae images for a multitude of conditions and indications. We included 315 subjects (174 with OSA and 141 without OSA) who performed at least two CT scans (under similar settings). Both groups had a similar duration between the first and second CT scans of 3.6 years. BMD decreased in those with OSA and increased age. A multivariate linear regression indicated that OSA is associated with BMD alterations after controlling for age, gender, and cardiovascular diseases. Here, we report that OSA is associated with BMD alterations. Further studies are required to untangle the complex affect of OSA on BMD and the possible clinical implications of vertebra-depressed or femoral neck fractures.

Molecular Mechanisms Involved in Hypoxia-Induced Alterations in Bone Remodeling

Bone is crucial for the support of muscles and the protection of vital organs, and as a reservoir of calcium and phosphorus. Bone is one of the most metabolically active tissues and is continuously renewed to adapt to the changes required for healthy functioning. To maintain normal cellular and physiological bone functions sufficient oxygen is required, as evidence has shown that hypoxia may influence bone health. In this scenario, this review aimed to analyze the molecular mechanisms involved in hypoxia-induced bone remodeling alterations and their possible clinical consequences. Hypoxia has been associated with reduced bone formation and reduced osteoblast matrix mineralization due to the hypoxia environment inhibiting osteoblast differentiation. A hypoxic environment is involved with increased osteoclastogenesis and increased bone resorptive capacity of the osteoclasts. Clinical studies, although with contradictory results, have shown that hypoxia can modify bone remodeling.

Relationship between obstructive sleep apnea-hypopnea syndrome and osteoporosis adults: A systematic review and meta-analysis

OBJECTIVE

This study is undertaken to explore the relationship between obstructive sleep apnea-hypopnea syndrome (OSAHS) and osteoporosis, including the relationship between OSAHS and osteoporosis incidence, lumbar spine bone mineral density (BMD), and lumbar spine T-score.

METHOD

Cochrane Library, PubMed, Embase, Web of Science, and other databases are searched from their establishment to April 2022. Literature published in 4 databases on the correlation between OSAHS and osteoporosis,lumbar spine BMD,lumbar spine T-score is collected. Review Manager 5.4 software is used for meta-analysis.

RESULTS

A total of 15 articles are selected, including 113082 subjects. Compared with the control group, the OSAHS group has a higher incidence of osteoporosis (OR = 2.03, 95% CI: 1.26~3.27, Z = 2.90, P = 0.004), the lumbar spine BMD is significantly lower (MD = -0.05, 95% CI: -0.08~-0.02, Z = 3.07, P = 0.002), and the lumbar spine T-score is significantly decreased (MD = -0.47, 95% CI: -0.79~-0.14, Z = 2.83, P = 0. 005).

CONCLUSION

Compared with the control group, the OSAHS group has a higher incidence of osteoporosis and decreased lumbar spine BMD and T-score. In order to reduce the risk of osteoporosis, attention should be paid to the treatment and management of adult OSAHS, and active sleep intervention should be carried out.

Lumbar spine abnormalities in patients with obstructive sleep apnoea

Previous studies suggested cervical spondylosis as a risk factor for development of obstructive sleep apnoea (OSA). We aimed to assess lumbar disc degeneration in patients with OSA and correlate the findings with symptoms and disease severity. Twenty-seven patients with OSA and 29 non-OSA controls underwent sleep studies and lumbar magnetic resonance imaging (MRI), and completed the Epworth Sleepiness Scale and the 24-item Roland-Morris Disability Questionnaire (RMDQ) questionnaires. Plasma klotho was determined with enzyme-linked immunosorbent assay. Patients with OSA had higher number of disc bulges (4.6 ± 3.7 vs. 1.7 ± 2.5, p < 0.01) and anterior spondylophytes (2.7 ± 4.2 vs. 0.8 ± 2.1, p < 0.01), increased disc degeneration (total Pfirrmann score 16.7 ± 4.7 vs. 13.2 ± 4.1, p < 0.01) and vertebral fatty degeneration (7.8 ± 4.7 vs. 3.8 ± 3.7, p < 0.01). There was no difference in the RMDQ score (0/0-3.5/ vs. 0/0-1/, p > 0.05). Markers of OSA severity, including the oxygen desaturation index and percentage of total sleep time spent with saturation < 90% as well as plasma levels of klotho were correlated with the number of disc bulges and anterior spondylophytes (all p < 0.05). OSA is associated with lumbar spondylosis. Our study highlights the importance of lumbar imaging in patients with OSA reporting lower back pain.

Sleep disruptions and bone health: what do we know so far?

PURPOSE OF REVIEW

This review briefly summarizes the growing body of literature addressing the skeletal consequences of sleep and circadian disruption.

RECENT FINDINGS

The most recent data in the field suggest that the diurnal variation in bone turnover markers are because of endogenous circadian rhythmicity linked to clock genes in all bone cells; in a small human intervention study, cumulative sleep restriction with concurrent circadian disruption negatively alter bone turnover markers in a way that could explain the lower BMD and increased fracture risk identified in some prior night shift work studies; abnormal sleep duration and obstructive sleep apnea are associated with low BMD and increased fracture risk in some but not all studies.

SUMMARY

Normal physiology and some animal and human intervention studies suggest that sleep and circadian disruptions, such as night shift work, abnormal sleep durations and obstructive sleep apnea are detrimental to skeletal health. However, additional research in this area is needed to determine which sleep/circadian disturbances are most detrimental to skeletal health, the reversibility of such impairments, and underlying mechanisms.

Sleep disturbance and bone mineral density, risk of falls and fracture: Results from a 10.7-year prospective cohort study

Sleep problems are common in the general population and have been linked to bone health, falls risk and fracture. However, longitudinal studies on sleep-bone health outcomes are lacking and no study has investigated whether an increased risk of fracture is attributable to sleep-related low bone mineral density (BMD) and an increased risk of falls. This study was designed to examine the associations of sleep disturbance with bone mineral density (BMD), risk of falls and fractures over 10.7 years. The analyses were performed in a population-based cohort study with 1099 participants (mean age 62.9 years) enrolled at baseline, and 875, 768 and 563 participants traced at a mean follow-up of 2.6, 5.1 and 10.7 years, respectively. At each visit, self-reported sleep disturbance was recorded. BMD (by dual-energy x-ray absorptiometry), falls risk score and fracture were measured at each visit. The short-form Physiological Profile Assessment was used to measure falls risk score expressed as Z-score. Fractures were self-reported. Mixed-effects model and generalized estimating equations were used for the analyses. In multivariable analysis, there was a dose-response relationship between the extent of sleep disturbance and falls risk score with the strongest association in those reporting the worst sleep disturbance (β = 0.15/unit; 95%CI 0.02-0.28). The worst sleep disturbance was associated with an increased risk of any (relative risk [RR] 1.30/unit; 95%CI 1.01-1.67) and vertebral fracture (RR 2.41/unit; 95%CI 1.00-5.80) compared with those reporting no interrupted sleep. Women but not men with sleep disturbance had a higher risk of vertebral fracture (RR: 2.07 to 6.02, P < 0.05). These were independent of covariates, hip BMD and falls risk. There was no statistically significant association between sleep disturbance and BMD at the hip, spine or total body. Sleep disturbance was independently associated with a greater falls risk score and an increased risk of fractures. Further research is needed to confirm and identify underlying mechanisms for these associations.

Unlocking mammalian regeneration through hypoxia inducible factor one alpha signaling

Historically, the field of regenerative medicine has aimed to heal damaged tissue through the use of biomaterials scaffolds or delivery of foreign progenitor cells. Despite 30 years of research, however, translation and commercialization of these techniques has been limited. To enable mammalian regeneration, a more practical approach may instead be to develop therapies that evoke endogenous processes reminiscent of those seen in innate regenerators. Recently, investigations into tadpole tail regrowth, zebrafish limb restoration, and the super-healing Murphy Roths Large (MRL) mouse strain, have identified ancient oxygen-sensing pathways as a possible target to achieve this goal. Specifically, upregulation of the transcription factor, hypoxia-inducible factor one alpha (HIF-1α) has been shown to modulate cell metabolism and plasticity, as well as inflammation and tissue remodeling, possibly priming injuries for regeneration. Since HIF-1α signaling is conserved across species, environmental or pharmacological manipulation of oxygen-dependent pathways may elicit a regenerative response in non-healing mammals. In this review, we will explore the emerging role of HIF-1α in mammalian healing and regeneration, as well as attempts to modulate protein stability through hyperbaric oxygen treatment, intermittent hypoxia therapy, and pharmacological targeting. We believe that these therapies could breathe new life into the field of regenerative medicine.

The Burden of Associated Comorbidities in Patients with Obstructive Sleep Apnea-Regional Differences in Two Central-Eastern European Sleep Centers

Background: Obstructive sleep apnea (OSA) is usually associated with cardiovascular and cerebrovascular disease, metabolic syndrome and depression. Data on relevant OSA-associated comorbidities in Central–European populations are scarce. The aim of this study was to compare the prevalence of comorbidities in two OSA cohorts from Hungary and Romania. Methods: Data from 588 (282 from Hungary, 306 from Romania) untreated patients with OSA were retrospectively analyzed. The prevalence rates of hypertension, diabetes, dyslipidemia, allergic rhinitis, asthma, chronic obstructive pulmonary disease (COPD), osteoporosis, cerebrovascular and cardiovascular disease, arrhythmia and depression were compared between the two populations following adjustment for demographics, body mass index, smoking history, comorbidities and sleep parameters. Results: The prevalence rates of hypertension, arrhythmia, cerebrovascular and cardiovascular disease, diabetes and COPD in the whole study population were directly related to the severity of OSA. We found an inverse correlation between the prevalence of osteoporosis and OSA severity (all p < 0.05). Following adjustment, the prevalence of dyslipidemia was higher in the Hungarian cohort, whilst the prevalence of asthma, cardiovascular and cerebrovascular diseases was higher in the Romanian cohort (all p < 0.05). Conclusions: There was no difference in the prevalence rate of most comorbidities in patients with OSA from the two cohorts, except for dyslipidemia, asthma, cardiovascular and cerebrovascular disease.

Osteoporosis in a Rat Model Co-Exposed to Cigarette Smoke and Intermittent Hypoxia

Purpose

There are few studies on osteoporosis in chronic obstructive pulmonary disease-obstructive sleep apnea overlap syndrome, and the results obtained are inconsistent. The purpose of our study is to observe the occurrence of osteoporosis and its possible mechanism in rat model co-exposed to cigarette smoke and intermittent hypoxia.

Materials and Methods

The rats were randomly divided into four groups: air exposed group, cigarette smoke (CS) exposed group, 10% concentration of intermittent hypoxia exposed group, CS combined with 10% concentration of intermittent hypoxia exposed group. All animals completed lung function and lung tissue morphology assessment. The femurs were examined by microcomputer tomography (microCT). Tartrate-resistant acidic phosphatase (TRAP) staining was used to evaluate the osteoclasts. We also assessed the interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α) in peripheral blood.

Results

There was no difference in the femoral length between each group, but the quantitative analyses of microCT showed that compared with the air exposed group, the percent bone volume (BV/TV), trabecular thickness (Tb.Th), trabecular number (Tb.N), cortical thickness (Ct.Th) and bone mineral density (BMD) decreased, and the trabecular separation (Tb.Sp) and the proportion of trap-positive cells increased significantly in the overlapping exposed group. There were higher levels of BV/TV in the overlapping group than CS exposed group. Compared with the intermittent hypoxia exposed group, there were lower levels of Tb.Th and Ct.Th and higher levels of Tb.Sp in the overlapping exposed group. However, there was no statistical difference of trap-positive cell between the overlapping exposed group and the CS exposed single group or the intermittent hypoxia exposed group. There were higher levels of IL-6 and TNF-α in the overlapping exposed group than those in the air-exposed group.

Conclusion

Bone destruction increased in the overlapping exposed rat model compared with the rat exposed to air, which may be related to the upregulation of inflammation.

Obstructive Sleep Apnea and Risk for Incident Vertebral and Hip Fracture in Women

Recent studies suggest a positive association between obstructive sleep apnea (OSA), a disorder associated with intermittent hypoxia and sleep fragmentation, and derangements in bone metabolism. However, no prospective study to date has investigated the association between OSA and fracture risk in women. We conducted a prospective study examining the relation between OSA and risk of incident vertebral fracture (VF) and hip fracture (HF) in the Nurses' Health Study. History of physician-diagnosed OSA was assessed by self-reported questionnaires. A previous validation study demonstrated high concordance between self-reports and medical record identification of OSA. OSA severity was further categorized according to the presence or absence of self-reported sleepiness. Self-reports of VF were confirmed by medical record review. Self-reported HF was assessed by biennial questionnaires. Cox proportional-hazards models estimated the hazard ratio for fracture according to OSA status, adjusted for potential confounders, including BMI, physical activity, calcium intake, history of osteoporosis, and falls, and use of sleep medications. Among 55,264 women without prior history of fracture, physician-diagnosed OSA was self-reported in 1.3% in 2002 and increased to 3.3% by 2012. Between 2002 and 2014, 461 incident VF cases and 921 incident HF cases were documented. The multivariable-adjusted hazard ratio (HR) for confirmed VF for women with history of OSA was 2.00 (95% CI, 1.29-3.12) compared with no OSA history, with the strongest association observed for OSA with daytime sleepiness (HR 2.86; 95% CI, 1.31-6.21). No association was observed between OSA history and self-reported HF risk (HR 0.83; 95% CI, 0.49-1.43). History of OSA is independently associated with higher risk of confirmed VF but did not have a statistically significant association with self-reported HF in women. Further research is warranted in understanding the role of OSA and intermittent hypoxia in bone metabolism and health that may differ by fracture site. © 2020 American Society for Bone and Mineral Research (ASBMR).

"Take My Bone Away?" Hypoxia and bone: A narrative review

To maintain normal cellular and physiological function, sufficient oxygen is required. Recently, evidence has suggested that hypoxia, either pathological or environmental, may influence bone health. It appears that bone cells are distinctly responsive to hypoxic stimuli; for better or worse, this is still yet to be elucidated. Hypoxia has been shown to offer potentially therapeutic effects for bone by inducing an osteogenic-angiogenic response, although, others have noted excessive osteoclastic bone resorption instead. Much evidence suggests that the hypoxic-inducible pathway is integral in mediating the changes in bone metabolism. Furthermore, many factors associated with hypoxia including changes in energy metabolism, acid-base balance and the increased generation of reactive oxygen species, are known to influence bone metabolism. This review aims to examine some of the putative mechanisms responsible for hypoxic-induced alterations of bone metabolism, with regard to osteoclasts and osteoblasts, both positive and negative.

Bone metabolism parameters and inactive matrix Gla protein in patients with obstructive sleep apnea†

STUDY OBJECTIVES

The aim of this study was to investigate differences in dual-energy X-ray absorptiometry (DXA) parameters, trabecular bone score (TBS), bone turnover markers and inactive matrix Gla protein (dp-ucMGP) between patients with obstructive sleep apnea (OSA) and healthy controls.

METHODS

This study enrolled 53 male patients diagnosed with OSA, and 50 age- and body mass index (BMI)-matched control subjects. All participants underwent DXA imaging, TBS assessment and blood sampling for biochemical analysis of bone metabolism markers.

RESULTS

Mean apnea-hypopnea index (AHI) score of OSA patients was 43.8 ± 18.8 events/h. OSA patients had significantly higher plasma dp-ucMGP levels in comparison to controls (512.7 ± 71.9 vs. 465.8 ± 50.9 pmol/L, p < 0.001). OSA and control group did not significantly differ regarding standard DXA results, while TBS values were significantly lower in the OSA group (1.24 ± 0.17 vs. 1.36 ± 0.15, p < 0.001). AHI score was a significant independent correlate of plasma dp-ucMGP levels (β ± SE, 1.461 ± 0.45, p = 0.002). In addition, TBS retained a significant relationship with dp-ucMGP values (β ± SE, -93.77 ± 38.1, p = 0.001).

CONCLUSIONS

dp-ucMGP levels are significantly higher in patients with OSA and correlate with disease severity. In addition, TBS values in OSA patients are lower in comparison with the control group and decrease with disease severity.

Can Hypoxic Conditioning Improve Bone Metabolism? A Systematic Review

Among other functions, hypoxia-inducible factor plays a critical role in bone–vascular coupling and bone formation. Studies have suggested that hypoxic conditioning could be a potential nonpharmacological strategy for treating skeletal diseases. However, there is no clear consensus regarding the bone metabolism response to hypoxia. Therefore, this review aims to examine the impact of different modes of hypoxia conditioning on bone metabolism. The PubMed and Web of Science databases were searched for experimental studies written in English that investigated the effects of modification of ambient oxygen on bone remodelling parameters of healthy organisms. Thirty-nine studies analysed the effect of sustained or cyclic hypoxia exposure on genetic and protein expression and mineralisation capacity of different cell models; three studies carried out in animal models implemented sustained or cyclic hypoxia; ten studies examined the effect of sustained, intermittent or cyclic hypoxia on bone health and hormonal responses in humans. Different modes of hypoxic conditioning may have different impacts on bone metabolism both in vivo and in vitro. Additional research is necessary to establish the optimal cyclical dose of oxygen concentration and exposure time.

The differences in the relationship between obstructive sleep apnea severity and trabecular bone score in men and women with type 2 diabetes

Aims

Type 2 diabetes mellitus (T2DM) and obstructive sleep apnea (OSA) may adversely affect bone. Gender is a well-established factor influencing bone health. We investigated the impact of OSA on bone mineral density (BMD) and trabecular bone score (TBS) in T2DM.

Methods

Eighty-one T2DM patients [33 men and 48 women] participated. OSA was diagnosed using an overnight monitor, with its severity assessed by an apnea hypopnia index (pAHI). The measurements of hypoxia, including the percentage of total sleep time in which oxygen saturation remains below 90% (pT90), the oxygen desaturation index (pODI) and minimum O₂ (min O₂), were reported. Lumbar spine (L1-4) and femoral neck (FN) BMD were measured using dual-energy X-ray absorptiometry (DXA). TBS was computed from DXA images.

Results

Sixty-five patients (80.2%) had OSA. pAHI, pT90, pODI and min O₂ were not correlated to L1-4 BMD, FN BMD or TBS in all participants by multiple regression analyses adjusting for age, gender and BMI. However, an interaction between gender and pAHI, and gender and pODI were significantly associated with TBS (b = 0.003, p = 0.034 and b = 0.004, p = 0.046, respectively). We therefore reassessed an association between pAHI or pODI and TBS separately between men and women. After adjusting for age and BMI, more severe OSA (higher pAHI) and higher pODI significantly associated with lower TBS (b = -0.002, p = 0.034 and b = -0.003, p = 0.021, respectively) in men. On the other hand, higher pAHI non-significantly associated with better trabecular microarchitecture as indicated by higher TBS (b = 0.002, p = 0.059) in women. When considered only postmenopausal (n = 33), higher pAHI and higher pODI were significantly associated with higher TBS (b = 0.004, p = 0.003 and b = 0.004, p = 0.008, respectively).

Conclusions

In T2DM patients, there is a complex interrelationship among OSA severity, gender and TBS. More severe OSA predicted lower TBS in men, but predicted higher TBS in postmenopausal women.

Sleep-Disordered Breathing Is Associated with Reduced Mandibular Cortical Width in Children

INTRODUCTION

Evidence from the adult population suggests that sleep-disordered breathing (SDB) (i.e., obstructive sleep apnea [OSA]) is negatively associated with bone mineral density. Whether a similar association exists in children with SDB has not been investigated. Using the mandibular cortical width (MCW) as a proxy for skeletal bone density, we investigated if children at risk of SDB or diagnosed with OSA have a reduced mandibular cortical width compared to children without SDB.

METHODS

Two retrospective cross-sectional studies were performed. The first study included comparison of MCW between 24 children with polysomnographically (PSG) diagnosed OSA and 72 age- and sex-matched control children. The second study included a cohort of children in which SDB was suggested by the Pediatric Sleep Questionnaire (PSQ) ( n = 101). MCW was measured from panoramic radiographs.

RESULTS

Multiple-predictors regression analysis from the first study indicated that in children with a severe form of SDB, as induced by OSA severity, there was a negative association with MCW (β = -0.290, P = 0.049). Moreover, PSG-diagnosed OSA children had thinner MCW (2.9. ± 0.6mm) compared to healthy children (3.5 ± 0.6 mm; P = 0.002). These findings were further supported by the second study illustrating that PSQ total scores were negatively associated with MCW (β = -0.391, P < 0.001).

CONCLUSIONS

Findings suggest that children at risk for or diagnosed with SDB exhibit reduced mandibular cortical width that purportedly may reflect alterations in bone homeostasis.

KNOWLEDGE TRANSFER STATEMENT

We report that sleep-disordered breathing (including its severe form, obstructive sleep apnea) in children is associated with reduced mandibular cortical width. This association might be a direct consequence of reduced bone health to sleep-disordered breathing or a reflection that reduced bone formation underlies the development of sleep-disordered breathing. Our findings suggest that mandibular cortical width can be used as an adjunct diagnostic parameter for the diagnosis of sleep-disordered breathing.

Association Between 25-Hydroxyvitamin D and Bone Mineral Density in People With Obstructive Sleep Apnea Syndrome

The aim of this study was to evaluate the association between bone mineral density (BMD) and 25-hydroxyvitamin D [25(OH) D] levels in patients with obstructive sleep apnea syndrome (OSAS). This study was designed as a cross-sectional and observational study. Patients who underwent polysomnography evaluation were classified as normal, mild, moderate, severe, or position-dependent OSAS, and OSAS + obesity hypoventilation syndrome (OHS). BMD was measured with the dual-energy X-ray absorptiometry method at the femur and lumbar spine. The chemiluminescence microparticle immunoassay was used for the measurement of 25(OH) D levels. A total of 126 patients (73 males, 53 females) with a mean age of 48.55 ± 11.8 years were included. Body mass index was significantly higher in the OSAS + OHS group than in the other groups (p < 0.01). There was no statistically significant difference between the groups in terms of total BMD, T-scores and Z-scores of the lumbar spine, femural neck, and total femur (p > 0.05 for all). Post hoc analyses showed that OSAS + OHS subgroup had lower level of 25(OH) D compared to the normal subjects (p = 0.006). Yet no significant difference was observed between the other OSAS groups. No significant correlation was observed between the apnea hypopnea index, the Epworth Sleepiness Scale scores, desaturation index, and BMD parameters (all for p > 0.05). While 25(OH) D levels were lower in OSAS + OHS patients, there was no statistically significant relationship between OSAS and BMD values.

Bone Metabolic Markers in Patients with Obstructive Sleep Apnea Syndrome

Background:

Obstructive sleep apnea syndrome (OSAS) is prevalent in obesity and is associated with many metabolic abnormalities. The relationship between OSAS and bone metabolism is still unclear. The aim of this study was to investigate the relationship between the severity of OSAS and bone metabolic markers.

Methods:

A total of 119 obese males were enrolled in this study in spring months from 2015 to 2017. All candidates underwent polysomnography, and their bone mineral density (BMD) and the serum levels of total procollagen type 1 N-terminal propeptide (t-P1NP), N-terminal midfragment of osteocalcin (N-MID), β-C-terminal telopeptide of type 1 collagen (β-CTX), vitamin D (VD), and parathyroid hormone (PTH) were measured. The analysis of variance and Pearson correlation analysis were performed for data analyses.

Results:

No significant differences in the mean values of BMD were observed among the obesity, mild-to-moderate OSAS, and severe OSAS groups; and the serum levels of t-P1NP and β-CTX in the severe OSAS group were significantly higher than those in the obesity group (48.42 ± 23.78 ng/ml vs. 31.98 ± 9.85 ng/ml, P < 0.001; 0.53 ± 0.24 ng/ml vs. 0.41 ± 0.13 ng/ml, P = 0.011, respectively). The serum level of VD in the obesity group was significantly higher than those in the mild-to-moderate and severe OSAS groups (both P < 0.001), and decreased as the severity of OSAS increased (P < 0.001). The serum level of PTH in the severey and mild-to-moderate OSAS groups (both P < 0.001). The results of correlation analysis indicated that the level of apnea-hypopnea index (AHI) was correlated with the levels of t-P1NP (r = 0.396, P < 0.001), VD (r = –0.404, P < 0.001), and PTH (r = 0.400, P < 0.001), whereas the level of minimum O₂ saturation (SaO₂ min) was correlated with the levels of VD (r = 0.258, P = 0.016) and PTH (r = –0.376, P < 0.001).

Conclusions:

The levels of bone resorption and formation markers in patients with severe OSAS were significantly increased compared to obese men, and the severity of OSAS was correlated with the serum levels of t-P1NP, VD, and PTH.

CKD-MBD: from the Pathogenesis to the Identification and Development of Potential Novel Therapeutic Targets

PURPOSE OF REVIEW

Although we have seen tremendous advances in the comprehension of CKD-MBD pathophysiology during the last few years, this was not accompanied by a significant change in mortality rate and quality of life. This review will address the traditional and updated pathophysiology of CKD-MBD along with the therapeutic limitations that affect CKD-MBD and proposed alternative treatment targets.

RECENT FINDINGS

An innovative concept brings the osteocyte to the center of CKD-MBD pathophysiology, in contrast to the traditional view of the skeleton as a target organ for disturbances in calcium, phosphate, parathyroid hormone, and vitamin D. Osteocytes, through the synthesis of FGF-23, sclerostin, among others, are able to interact with other organs, making bone an endocrine organ. Thus, osteocyte dysregulation might be an early event during the course of CKD. This review will revisit general concepts on the pathophysiology of CKD-MBD and discuss new perspectives for its treatment.

Sleep apnea and femoral neck BMD among Singaporean mid-life women

The relationship between sleep apnea and bone health remains controversial. This study explored the relationship between sleep apnea and femoral neck BMD in midlife Asian women. Partner-witnessed apnea predicted higher femoral neck BMD, an effect validated by the STOP index. Our findings suggest that sleep apnea may protect bone health.

PURPOSE

The menopause transition is associated with decline in bone mineral density (BMD) and sleep quality. However, any relationship between these two factors remains controversial. This study explored the association between sleep apnea and femoral neck BMD in middle-aged women.

METHODS

Participants (n = 1201) aged 45-69 years attending well-women visits at the National University Hospital, Singapore were recruited. Self-reported breathing discomfort and snoring, partner-witnessed apnea and snoring were assessed from the Pittsburgh Sleep Quality Index. Femoral neck BMD was assessed with dual-energy X-ray absorptiometry scan and classified into tertiles based on T-scores. Factors reported to affect sleep apnea and bone health in medical literature were potential covariates, p < 0.10. Multivariable ordinal regression analyses assessed associations between sleep measures and BMD. To further validate our findings, we analyzed four sleep apnea characteristics from the STOP questionnaire, a screening tool for sleep apnea. All analyses were performed using SPSS version 20.0.

RESULTS

Mean (SD) age of participants was 56.3 (6.2) years. Partner-witnessed apnea predicted higher BMD tertiles (OR per unit increase in severity 1.39, 95% CI [1.02, 1.89]), independent of age, ethnicity, diabetes, BMI, and handgrip strength. This was further corroborated by the STOP index (OR 1.45, 95% CI [1.07, 1.96]).

CONCLUSIONS

This study adds to the literature on sleep apnea and bone health in a non-Caucasian and younger population. Our findings support OSA-associated intermittent hypoxia protecting bone health.

Association between obstructive sleep apnea and comorbidities with periodontal disease in adults

Background:

Several studies have reported an association between periodontal disease and obstructive sleep apnea (OSA). However, heterogeneity of results suggests that there is insufficient evidence to support this association.

Aims:

The objective of this study was to identify the association between periodontal disease and OSA in adults with different comorbidities.

Settings and Design:

One hundred and ninety-nine individuals (107 women and 92 men) underwent polysomnography with a mean age of 49.9 years were recruited.

Materials and Methods:

The presence of OSA, comorbidities, and periodontal disease was evaluated in each individual. Student's t-tests or Chi-square and ANOVA tests were used to determine the differences between groups.

Results:

The prevalence of periodontal disease was 62.3% and 34.1% for gingivitis. The results showed no statistically significant association between all groups of patients with OSA and non-OSA patients for gingivitis (P = 0.27) and for periodontitis (P = 0.312). However, statistically significant association was shown between periodontitis and mild OSA compared with the periodontitis and non-OSA referent (P = 0.041; odds ratio: 1.37 and 95% confidence interval 1.11–2.68). The analysis between OSA and comorbidities showed a statistically significant difference for patients with OSA and hypertension (P < 0.001) and for patients with OSA and hypertensive cardiomyopathy (P < 0.001) compared with healthy individuals. Periodontitis was more likely in men with severe OSA and with any of two comorbidities such as hypertension or hypertensive cardiomyopathy. Women with hypertension or hypertensive cardiomyopathy were more likely to have mild OSA, and these associations were statistically significant (P < 0.05).

Conclusions:

This study identified association between periodontitis and mild OSA and this association was more frequent in women with hypertension or hypertensive cardiomyopathy. Periodontitis was associated with severe OSA in men who showed any of two comorbidities such as hypertension or hypertensive cardiomyopathy.

Obstructive sleep apnea and hormones - a novel insight

Obstructive sleep apnea (OSA), a disorder characterized by repetitive collapse of the upper respiratory tract during sleep, occurs in about 4% of middle-aged men and 2% of women. The incidence of the disorder is rising due to an increase in obesity and ageing of the population. Patients with obstructive sleep apnea are at elevated risk of some endocrinal and metabolic disorders, which may lead to serious consequences including shortening of life expectancy. The recognition and understanding of interactions between local upper airway dysfunction and its endocrinal consequences is therefore vital. In this review we will focus on the influence of OSA on bone metabolism and endocrine homeostasis.

Association between sleep apnea and low bone mass in adults: a systematic review and meta-analysis

We performed a systematic review of the literature to assess the association between sleep apnea and bone metabolism diseases including osteoporosis in adult population. Results from clinical trials suggest that the association between sleep apnea and low bone mass in adults is possible.

INTRODUCTION

This study aimed to synthesize existing evidence on the potential association between sleep apnea and low bone mass in adults.

METHODS

Electronic searches of five databases were performed. The inclusion criteria consisted of studies in humans that assessed potential associations between sleep apnea and bone metabolic diseases in an adult population. For diagnosis of sleep apnea overnight polysomnography, home polygraphy, or validated records from healthcare databases were considered. Reduced bone density, osteoporosis, serum/urinary levels for markers of bone formation and resorption, or risk of fractures caused without history of trauma were considered indicators of low bone mass. A random-effects model meta-analysis was applied when possible.

RESULTS

Of the 963 relevant references, 12 studies met our inclusion criteria and were assessed to be of medium to low bias. Nine out of 12 studies reported an association between sleep apnea and low bone mass (increased bone resorption markers, reduced bone density, and higher risk of osteoporosis). Two studies did not report a significant association, whereas one study reported an increase of bone density in sleep apnea patients compared to non-sleep apnea patients. Meta-analysis of 2 studies (n = 112,258 patients) showed that sleep apnea was a significant risk factor for osteoporosis (odds ratio (OR), 1.92; 95%CI, 1.24 to 2.97; I² = 66%); females only had an OR of 2.56 (95% CI, 1.96 to 3.34; I² = 0%) while the OR in males was 2.03 (95% CI, 1.24 to 3.35; I² = 38%).

CONCLUSIONS

An association between sleep apnea and low bone mass in adults is plausible, but supporting evidence has a risk of bias and is inconsistent.

Adenotonsillectomy outcomes regarding bone age and osteocalcin in treatment of obstructive sleep apnea syndrome in children

BACKGROUND

To investigate the effect of adenotonsillectomy (AT) on bone development, quality of life and polysomnography evaluation in children with obstructive sleep apnea syndrome (OSA).

METHODS

Preoperative and postoperative (6 months) physical examination, PSG, bone age (BA) and osteocalcin (OC) evaluation were performed on the selected OSA children (n=92) and the healthy children (n=87). The OSA children were also scored based on the OSA 18-item questionnaire. A two-year follow-up was conducted to evaluate BA and OC changes.

RESULTS

After AT, 81 (88.04%) OSA children recovered completely, eight (8.70%) achieved remarkable improvements, and three (3.26%) achieved moderate improvements. In the OSA children, postoperative OSA 18-item score and the scores of the five domains were significantly higher than preoperative ones. Compared with the preoperative, body mass index (BMI), weight for age Z-sores, height for age Z-sores, weight for height Z-sores and BMI Z-score in the OSA group 6 months after the operation were significantly increased, but no significant difference was detected between the OSA and the control group. The changes of BA and chronological age in the OSA group were significantly different from those in the control group. Two years after AT, BA between the two groups was no longer significantly different. Preoperative serum OC in the OSA group was lower than that in the control group, but increased to normal levels 6 months after AT. Correlation analysis showed serum OC levels were negatively correlated with apnea hyponea index, obstructive apnea index, arousal index, and lowest oxygen saturation.

CONCLUSIONS

After AT, bone growth and development in children with OSA recovered gradually, and the serum OC levels decreased to the normal level. Therefore, preventive measures and positive treatments should be applied to minimize the negative effects of OSA in children.

Evaluation of Bone Mineral Density by Computed Tomography in Patients with Obstructive Sleep Apnea

STUDY OBJECTIVES

Clinical studies have investigated whether obstructive sleep apnea (OSA) can modulate bone metabolism but data are conflicting. Bone mineral density (BMD) measured by dual-energy x-ray absorptiometry is the standard technique for quantifying bone strength but has limitations in overweight patients (body mass index [BMI] ≥ 25 kg/m(2)). The aim of this study was to examine the association between OSA and BMD by examining CT images that allow true volumetric measurements of the bone regardless of BMI.

METHODS

Lumbar vertebrae BMD was evaluated in 234 persons (180 males and 54 females) by CT scan. The method was calibrated by a phantom containing a known concentration of hydroxyapatite.

RESULTS

BMD was lower in male patients with severe OSA (apnea-hypopnea index [AHI] ≥ 30/h) than non OSA (AHI < 5; p < 0.05), while OSA and BMD had no association in females. Linear and multiple regression analyses revealed that age (p < 0.0001, β = -0.52), hypertension (p = 0.0068, β = -0.17), and the alveolar-arterial oxygen pressure difference (A-aDO2) (p = 0.012, β = -0.15) in males were associated with BMD, while only age (p < 0.0001, β = -0.68) was associated with BMD in females.

CONCLUSION

Males with severe OSA had a significantly lower BMD than non OSA participants. Age, hypertension, and elevation of A-aDO2 were significant factors for BMD by CT imaging. The usefulness of measuring BMD in OSA patients by CT scanning should be studied in future.

Does Subjective Sleep Affect Bone Mineral Density in Older People with Minimal Health Disorders? The PROOF Cohort

STUDY OBJECTIVES

Clinical and epidemiological studies suggest a relation between bone mineral density (BMD) and self-assessment of sleep with an effect on bone formation and osteoporosis (OS) risk in short and long sleepers. This study explores this association in a large sample of older subjects.

METHODS

We examined 500 participants without insomnia complaints aged 65.7 ± 0.8 y. Each participant had a full evaluation including anthropometric measurement, clinical examination and measurements of BMD at the lumbar spine and femoral sites by dual-energy X-ray absorptiometry. The daily energy expenditure (DEE) was measured by the Population Physical Activity Questionnaire. Sleep duration and quality were evaluated by the Pittsburgh Sleep Quality Index. The subjects were stratified into three groups according to sleep duration, i.e., short (< 6 h), normal (6-8 h), and long (≥ 8 h) sleepers.

RESULTS

Osteopenia was found in 40% of the subjects at the femoral level and 43% at the vertebral level. The prevalence of OS was lower both at femoral (8%) and vertebral (12%) levels. Short, normal, and long sleepers accounted for 29%, 40%, and 31% of subjects, respectively. After adjustments for metabolic, anthropometric, and DEE, multinomial logistic regression analysis indicated that long sleepers were more likely to have femoral neck OS with a slight effect of DEE at vertebral spine.

CONCLUSIONS

In a sample of older subjects, self-reported long sleep was the best predictor of OS risk at the femoral level. This finding suggests an association between OS and self-reported sleep duration in older subjects.

CLINICAL TRIAL REGISTRATION

NCT 00759304 and NCT 00766584.

Intermittent Hypoxia Influences Alveolar Bone Proper Microstructure via Hypoxia-Inducible Factor and VEGF Expression in Periodontal Ligaments of Growing Rats

Intermittent hypoxia (IH) recapitulates morphological changes in the maxillofacial bones in children with obstructive sleep apnea (OSA). Recently, we found that IH increased bone mineral density (BMD) in the inter-radicular alveolar bone (reflecting enhanced osteogenesis) in the mandibular first molar (M1) region in the growing rats, but the underlying mechanism remains unknown. In this study, we focused on the hypoxia-inducible factor (HIF) pathway to assess the effect of IH by testing the null hypothesis of no significant differences in the mRNA-expression levels of relevant factors associated with the HIF pathway, between control rats and growing rats with IH. To test the null hypothesis, we investigated how IH enhances mandibular osteogenesis in the alveolar bone proper with respect to HIF-1α and vascular endothelial growth factor (VEGF) in periodontal ligament (PDL) tissues. Seven-week-old male Sprague-Dawley rats were exposed to IH for 3 weeks. The microstructure and BMD in the alveolar bone proper of the distal root of the mandibular M1 were evaluated using micro-computed tomography (micro-CT). Expression of HIF-1α and VEGF mRNA in PDL tissues were measured, whereas osteogenesis was evaluated by measuring mRNA levels for alkaline phosphatase (ALP) and bone morphogenetic protein-2 (BMP-2). The null hypothesis was rejected: we found an increase in the expression of all of these markers after IH exposure. The results provided the first indication that IH enhanced osteogenesis of the mandibular M1 region in association with PDL angiogenesis during growth via HIF-1α in an animal model.

Association Between Obstructive Sleep Apnea and Osteoporosis: A Systematic Review and Meta-Analysis

CONTEXT

Hypoxia reduces osteoblast growth resulting in bone thinning and osteoporosis. Although obstructive sleep apnea (OSA) with recurrent hypoxia might be a contributing factor for osteoporosis development, whether OSA is a risk or protective factor for osteoporosis has not been demonstrated.

OBJECTIVES

This systematic review and meta-analysis evaluated the association between OSA and osteoporosis using published observational studies.

DATA SOURCES

PubMed/MEDLINE and EMBASE databases.

STUDY SELECTION

We completed a systematic review and meta-analysis of published observational studies that evaluated incidence or prevalence of osteoporosis or bone mineral density in obstructive sleep apnea compared with controls. Severity of OSA was characterized using the apnea-hypopnea index (AHI).

DATA EXTRACTION

Primary outcomes were incidence, prevalence, or odds ratio of having osteoporosis, defined as bone mineral density T-score < -2.5 SD.

RESULTS

Of 353 articles, 344 articles were excluded, 9 underwent full-length review and data were extracted from 7 studies consisting of 113,558 patients. Finally, 3 extracted studies were included in the meta-analysis of osteoporosis. Among cohort studies, the pooled odds ratio of osteoporosis in patients with OSA was 1.92 (95% confidence interval [CI]: 1.24 - 2.97) compared with controls. Among cross-sectional studies, odds of osteoporosis was higher in controls compared with patients with OSA (OR = 0.60, 95% CI: 0.42 - 0.87). In subgroup analysis by gender and study design, in both sexes, only cohort studies had higher odds of osteoporosis compared with controls.

CONCLUSIONS

There was significant association between OSA and osteoporosis in studies with cohort design. Further prospective studies with large numbers of patients adjusted for the effects of age, sex, or BMI are required to comprehensively determine whether OSA is a risk factor for osteoporosis.

Bone mineral density and changes in bone metabolism in patients with obstructive sleep apnea syndrome

The aim of this study was to evaluate the differences between patients with obstructive sleep apnea syndrome (OSAS) and phenotypically similar subjects without OSAS in terms of bone mineral density (BMD) and bone turnover markers. The study was conducted on 30 males diagnosed with OSAS and 20 healthy males. All subjects underwent polysomnographic testing. Calcium, phosphorus parathyroid hormone, thyroid stimulating hormone, bone-specific alkaline phosphatase, 25-hydroxyvitamin D3, osteocalcin, and beta-CrossLaps (β-CTx) were measured. BMD in the lumbar spine (L1-L4) and femoral neck was measured by dual energy X-ray absorptiometry. There was no statistically significant difference between the two groups in terms of demographic data with the exception of bone mass index and waist circumference. (p < 0.05). Analyses showed significantly lower BMD measurements in the femoral neck and T-scores in the femoral neck in patients diagnosed with OSAS. Serum β-CTx levels were found to be statistically significantly higher in the OSAS group (p = 0.017). In multivariate assessments performed for apnea/hypopnea index values, mean saturation O2 levels were found to be significantly associated with osteocalcin levels and neck BMD. OSAS patients might represent a risk group with respect to loss of BMD and bone resorption. It is important to evaluate bone loss in these patients. Further studies should be carried out on larger study populations to evaluate the effects of chronic hypoxia on BMD in detail.

Intermittent hypoxia induces disturbances in craniofacial growth and defects in craniofacial morphology

OBJECTIVES

To investigate intermittent hypoxia (IH) induced changes in craniofacial morphology and bone mineral density (BMD) in the mandible of growing rats.

DESIGN

Seven-week-old male Sprague-Dawley rats were exposed to IH for 4 days or 3 weeks. Sham-operated rats simultaneously breathed room air. Lateral and transverse cephalometric radiographs of the craniofacial region were obtained, and the linear distances between cephalometric landmarks were statistically analyzed. BMD and bone microstructure of the mandible were evaluated using micro-computed tomography (micro-CT).

RESULTS

Cephalometric analyses demonstrated that exposure to IH only in the two groups for 3 weeks decreased the size of the mandibular and viscerocranial bones, but not that of the neurocranial bones, in early adolescent rats. These findings are consistent with upper airway narrowing and obstructive sleep apnea (OSA). Micro-CT showed that IH increased the BMD in the cancellous bone of the mandibular condyle and the inter-radicular alveolar bone in the mandibular first molar (M1) region.

CONCLUSIONS

This study is the first to identify growth retardation of the craniofacial bones in an animal model of sleep apnea. Notably, 3 weeks of IH can induce multiple changes in the bones around the upper airway in pubertal rats, which can enhance upper airway narrowing and the development of OSA. The reproducibility of these results supports the validity and usefulness of this model. These findings also emphasize the critical importance of morphometric evaluation of patients with OSA.

Periodontitis and Sleep Disordered Breathing in the Hispanic Community Health Study/Study of Latinos

STUDY OBJECTIVES

To investigate the association between sleep disordered breathing (SDB) and severe chronic periodontitis.

DESIGN

Cross-sectional data analysis from the Hispanic Community Health Study/Study of Latinos.

SETTING

Community-based setting with probability sampling from four urban US communities.

PARTICIPANTS

12,469 adults aged 18-74 y.

INTERVENTIONS

None.

MEASUREMENTS AND RESULTS

Severe chronic periodontitis was defined using the Centers for Disease Control and Prevention/American Academy of Periodontology case classification based on full-mouth periodontal assessments performed by calibrated dentists. SDB was evaluated in standardized home sleep tests, and defined as the number of apnea plus hypopnea events associated with ≥ 3% desaturation, per hour of estimated sleep. SDB was quantified using categories of the apnea-hypopnea index (AHI): 0.0 events (nonapneic); 0.1-4.9 (subclinical); 5.0-14.9 (mild); and ≥ 15 (moderate/severe). Covariates were demographic characteristics and established periodontitis risk factors. C-reactive protein was a potential explanatory variable. Using survey estimation, multivariable binary logistic regression estimated odds ratios (OR) and 95% confidence limits (CL). Following adjustment for confounding, the SDB and periodontitis relationship remained statistically significant, but was attenuated in strength and no longer dose-response. Compared with the nonapneic referent, adjusted odds of severe periodontitis were 40% higher with subclinical SDB (OR = 1.4, 95% CL: 1.0, 1.9), 60% higher with mild SDB (OR = 1.6, 95% CL: 1.1, 2.2) and 50% higher with moderate/severe SDB (OR = 1.5, 95% CL: 1.0, 2.3) demonstrating an independent association between SDB and severe periodontitis.

CONCLUSIONS

This study identifies a novel association between mild sleep disordered breathing and periodontitis that was most pronounced in young adults.

Correlations between osteoprotegerin serum levels and body composition parameters in patients with sleep apnea syndrome and the possible influence on cardiovascular risk

INTRODUCTION

Osteoprotegerin (OPG) is a member of the tumor necrosis factor family and a key regulator in bone turnover; it plays a role in the development of many cardiovascular diseases and may be treated as a marker of vascular damage. Bioelectrical impedance analysis (BIA) is a reliable, non-invasive and effective technique for measuring body composition. The aim of the study was to evaluate correlations between osteoprotegerin serum levels and body composition parameters in sleep apnea patients and their influence on cardiovascular risk.

MATERIAL AND METHODS

A total of 125 patients with newly diagnosed OSA were enrolled in the study (including 34 females). The mean age was 54.48±8.81 years, mean AHI 33.16±20.44/h and mean BMI 33.76±7.18. A control group comprised 59 healthy subjects with mean age of 51.27±12.97 years and mean BMI 29.47±5.42. All subjects underwent a nocturnal respiratory polygraphy and body composition measurements were taken with bioelectrical impedance analysis. OPG serum levels were measured using the enzyme-linked immunosorbent assay (ELISA) method.

RESULTS

In OSA patients OPG correlated negatively with muscle mass percentage (MM%), phase angle, fat free mass percentage (FFM%) and body cell mass percentage (BCM%), while there was a positive correlation between osteoprotegerin and fat mass percentage (FM%). We demonstrated higher OPG serum levels in OSA patients with cardiovascular diseases than in those without comorbidities (4.01 vs 3.46pmol/l, p<0.05).

CONCLUSION

Our findings, combined with previous observations in other diseases, suggest that elevated OPG serum levels together with selected body composition parameters may be helpful in identifying OSA patients with increased cardiovascular risk.

Obstructive sleep apnea and metabolic bone disease: insights into the relationship between bone and sleep

Obstructive sleep apnea (OSA) and low bone mass are two prevalent conditions, particularly among older adults-a section of the U.S. population that is expected to grow dramatically over the coming years. OSA, the most common form of sleep-disordered breathing, has been linked to multiple cardiovascular, metabolic, hormonal, and inflammatory derangements and may have adverse effects on bone. However, little is known about how OSA (including the associated hypoxia and sleep loss) affects bone metabolism. In order to gain insight into the relationship between sleep and bone, we review the growing information on OSA and metabolic bone disease and discuss the pathophysiological mechanisms by which OSA may affect bone metabolism/architecture.

Sleep disorders increase the risk of osteoporosis: a nationwide population-based cohort study

BACKGROUND

This study evaluated the relationship between sleep disorders (SDs) and osteoporosis risk in Taiwan.

METHODS

From the Taiwan National Health Insurance data, we identified 44,690 newly diagnosed SD patients (846 with apnea and 43,844 without) from 1998 to 2001 and 89,380 comparisons without SD in the same period frequency matched by sex, age and diagnosis year. Incident osteoporosis was measured by the end of 2010.

RESULT

Patients with apnea-SD and nonapnea SD exhibited a higher osteoporosis incidence rate than did the comparisons (9.97 and 13.3 vs. 6.77 per 1000 person-years, respectively). The Cox method estimated adjusted hazard ratio (HR) of osteoporosis was 2.98 (95% confidence interval [CI] = 2.36-3.74) in apnea-SD patients, compared with 2.76 (95% CI = 2.64-2.88) in nonapnea-SD patients after controlling for sex, age, comorbidities, and treatment. Greater HRs of osteoporosis were observed for female patients (4.00, 95% CI = 3.72-4.29) and those aged >64 years (42.0, 95% CI = 33.5-52.7) in the apnea SD sub-cohort. Apnea SD was associated with the highest risk of osteoporosis without fracture compared with both the nonapnea SD sub-cohort and comparisons.

CONCLUSION

Patients with sleep disorders have an elevated risk of osteoporosis, especially for women and the elderly.

Obstructive sleep apnea and risk of osteoporosis: a population-based cohort study in Taiwan

BACKGROUND

Obstructive sleep apnea (OSA) is associated with metabolic, endocrine, and cardiovascular diseases. It is characterized by repetitive episodes of apnea/hypopnea and hypoxia in tissues, which might also impact bone metabolism. This study investigates the possible association between OSA and osteoporosis.

METHODS

Random samples of 1 million individuals were collected from Taiwan's National Health Insurance database. A total of 1377 patients with newly diagnosed OSA from 2000 to 2008 were recruited and compared with a matched cohort of 20 655 patients without OSA. All patients were tracked until an osteoporosis diagnosis, death, or the end of 2011.

RESULTS

During the 6-year follow-up period, the incidence rates of osteoporosis in the OSA cohort and comparison group were 2.52 and 1.00 per 1000 person-years, respectively. Patients with OSA were found to be at 2.74 times the risk of osteoporosis than patients without OSA (95% confidence interval 1.69-4.44, P < .05), after adjustment for age, gender, diabetes, hypertension, coronary artery disease, obesity, stroke, hyperlipidemia, chronic kidney disease, gout, monthly income, and geographical location. Subgroup analysis showed that older patients and female patients had a higher risk for osteoporosis than their younger and male counterparts. Log-rank analysis revealed that patients with OSA patients had significantly higher cumulative incidence rates of osteoporosis than the comparison group (P < .0001).

CONCLUSION

People diagnosed with OSA are at increased risk for subsequent osteoporosis.

Impairment of nasal airway under intermittent hypoxia during growth period in rats

OBJECTIVE

To clarify the influences of intermittent hypoxia (IH) on the growth and development of the midfacial area, including the nasal cavity, in growing rats.

DESIGN

Seven-week-old male Sprague-Dawley rats were divided into two groups: the experimental group (n=5), which was exposed to IH for 8h during light periods at a rate of 20 cycles/h (nadir, 4% O₂ to peak, 21% O₂ with 0% CO₂), and the control group (n=5), which was exposed to room air. After 3 weeks, the maxillofacial structures in both groups were evaluated with respect to the height, width, length, surface area, cross-sectional area, and volume of the nasal cavity using soft X-ray and micro-CT.

RESULTS

The experimental group showed a significantly smaller cross-sectional area and volume than did the control group. The surface area exhibited no significant differences between the two groups, although it tended to be smaller in the experimental group than in the control group. The nasal volume divided by the length of the tibia (for comparison with whole-body growth) was significantly smaller in the experimental group than in the control group.

CONCLUSIONS

These data suggest that IH exposure suppresses growth and development of the nasal cavity and may result in nasal breathing disturbance.