An observational study in Obesity Hypoventilation Syndrome (OHS) and Obstructive Sleep Apnea (OSA), sponsored by Chang Gung Memorial Hospital. Completed at 1 site in Taiwan. Open to participants aged 20 Years to 65 Years. Per ClinicalTrials.gov, last updated 2025-06-13.
Sponsored by Chang Gung Memorial Hospital · Observational
The aims of this prospective observational cohort study are threefold: (1) to assess the prevalence of obesity hypoventilation syndrome (OHS) in individuals with obesity and obstructive sleep apnea (OSA) and identify associated risk factors, (2) to determine clinical predictors of OHS, and (3) to evaluate the therapeutic outcomes of combined airway and bariatric surgery (CABS) in this population.
This study was approved by the Institutional Review Board of Chang Gung Medical Foundation on August 8, 2022 (IRB No. 202201000A3). Written informed consent was obtained from all participants. All procedures adhered to the principles outlined in the Declaration of Helsinki and were reported in accordance with the Strengthening the Reporting of Observational Studies in Epidemiology (STROCSS) guidelines.
This was a two-year prospective observational cohort study conducted at the tertiary referral sleep center of Linkou Chang Gung Memorial Hospital from December 1, 2022, to November 30, 2024. Obesity hypoventilation syndrome (OHS) was diagnosed based on the presence of BMI ≥ 30 kg/m², PaCO₂ ≥ 45 mmHg on arterial blood gas (ABG) analysis, and sleep-disordered breathing, following the exclusion of other potential causes of alveolar hypoventilation using pulmonary function tests.
Adults aged 20 to 65 years were eligible if they met the following inclusion criteria: (1) BMI ≥ 30 kg/m², and (2) AHI ≥ 5 events/hour. Individuals were excluded if they had (1) persistent decompensated hypercapnic respiratory failure (arterial pH \< 7.3), (2) acute respiratory failure requiring invasive mechanical ventilation, (3) significant neuromuscular disease, chest wall deformities, or pulmonary disease contributing to hypoventilation, (4) unstable coronary artery disease, or (5) cognitive impairment precluding informed consent or protocol adherence.
Following diagnosis, individuals with OHS were counseled on therapeutic options, including continuous positive airway pressure (CPAP) therapy, body weight reduction, or combined airway and bariatric surgery (CABS). The final decision was made through a shared decision-making process.
Outcome measures included (1) Polysomnography: All participants underwent attended level I polysomnography using the Nicolet UltraSom System (Nicolet, Madison, WI). AHI was the primary sleep parameter, defined as the total number of apneas (≥ 90% airflow reduction for ≥10 seconds) and hypopneas (> 50% airflow reduction with ≥ 3% oxygen desaturation or arousal) per hour of sleep. Scoring was performed by a single blinded sleep specialist. (2) Pulmonary function testing: Spirometry was performed using a handheld spirometer in accordance with international guidelines. Parameters included forced vital capacity (FVC), forced expiratory volume in 1 second (FEV₁), and FEV₁/FVC ratio. (3) Gas exchange: ABG analysis was conducted during daytime hours with the participant seated and breathing room air after resting for at least 60 minutes. (4) Epworth sleepiness scale: Daytime sleepiness was assessed using the Epworth Sleepiness Scale (ESS), a validated 8-item questionnaire with total scores ranging from 0 to 24; higher scores indicate greater daytime sleepiness.
The prevalence of OHS was calculated as the proportion of individuals diagnosed with OHS among those with concurrent obesity and obstructive sleep apnea (OSA). A multivariate logistic regression analysis with forward selection was conducted to identify independent predictors of OHS. Receiver operating characteristic (ROC) curve analysis was used to determine the optimal cut-off points for various predictors. To evaluate the effects of the CABS intervention, pre- and post-operative changes in clinical parameters were compared.
73 studies on the registry are indexed under Obesity Hypoventilation Syndrome; 10 are open to participants now.
This study's enrollment of 36 is below the median of 50 across 25 observational studies indexed under Obesity Hypoventilation Syndrome.
Browse Obesity Hypoventilation Syndrome studies →Chang Gung Memorial Hospital is the lead sponsor of 1,096 studies on the registry; 239 are open to participants now.
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This study enrolled consecutive patients with obesity and OSA at the tertiary referral sleep center of Linkou Chang Gung Memorial Hospital from September 1, 2022, to August 31, 2024. OHS was diagnosed based on the presence of BMI ≥ 30 kg/m², PaCO₂ ≥ 45 mmHg on ABG analysis, and sleep-disordered breathing, following the exclusion of other potential causes of alveolar hypoventilation using pulmonary function tests.
Go through the criteria one by one — yes, no or not sure — and take the list to your doctor or the study team. Kept in this browser only.
(1) ≥ 30 kg/m², and (2) AHI ≥ 5 events/hour.
Exclusion Criteria:
(1) persistent decompensated hypercapnic respiratory failure (arterial pH \< 7.3), (2) acute respiratory failure requiring invasive mechanical ventilation, (3) significant neuromuscular disease, chest wall deformities, or pulmonary disease contributing to hypoventilation, (4) unstable coronary artery disease, or (5) cognitive impairment precluding or protocol adherence.
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Weight in kilograms divided by height in metres squared. Example: 70 kg and 1.75 m gives 70 ÷ (1.75 × 1.75) ≈ 22.9.
What counts as overweight or obesity differs between countries (some use lower cut-offs), so go by the range the study states.
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
BMI (body mass index)
Weight in kilograms divided by height in metres squared. Example: 70 kg and 1.75 m gives 70 ÷ (1.75 × 1.75) ≈ 22.9.
What counts as overweight or obesity differs between countries (some use lower cut-offs), so go by the range the study states.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Informed consent
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Adults aged 20 to 65 years were eligible if they met the following inclusion criteria: (1) BMI ≥ 30 kg/m², and (2) AHI ≥ 5 events/hour. OSA was diagnosed by standard polysomnography. OHS was diagnosed based on the presence of BMI ≥ 30 kg/m², PaCO₂ ≥ 45 mmHg on arterial blood gas (ABG) analysis, and sleep-disordered breathing, following the exclusion of other potential causes of alveolar hypoventilation using pulmonary function tests.
Procedure: CABS
Following diagnosis, individuals with OHS were counseled on therapeutic options, including CPAP therapy, body weight reduction, or CABS. The final decision was made through a shared decision-making process. The CABS procedure was conducted under general anesthesia and integrated bariatric and multilevel airway surgery within a single operative session. This transdisciplinary approach aimed to address both sleep-disordered breathing and obesity-related ventilatory compromise. A general surgeon performed the bariatric procedure, while an otorhinolaryngologist conducted the airway surgery sequentially during the same operation. For the bariatric component, laparoscopic sleeve gastrectomy (LSG) was the primary procedure, while laparoscopic Roux-en-Y gastric bypass was reserved for individuals with significant gastroesophageal reflux or poorly controlled diabetes. Airway surgery encompassed interventions at the nasal, palatal, and lingual levels.
AHI
All participants underwent attended level I polysomnography using the Nicolet UltraSom System (Nicolet, Madison, WI). Apnea-hypopnea index (AHI) was the primary sleep parameter, defined as the total number of apneas (≥ 90% airflow reduction for ≥10 seconds) and hypopneas (\> 50% airflow reduction with ≥ 3% oxygen desaturation or arousal) per hour of sleep. Scoring was performed by a single blinded sleep specialist.
Time frame: From enrollment to the end of treatment at 12 months.
FEV₁/FVC ratio
Spirometry was performed using a handheld spirometer in accordance with international guidelines. Parameters included forced vital capacity (FVC), forced expiratory volume in 1 second (FEV₁), and FEV₁/FVC ratio.
Time frame: From enrollment to the end of treatment at 12 months.
PaCO₂
Arterial blood gas (ABG) analysis was conducted during daytime hours with the participant seated and breathing room air after resting for at least 60 minutes.
Time frame: From enrollment to the end of treatment at 12 months
ESS score
Daytime sleepiness was assessed using the Epworth Sleepiness Scale (ESS), a validated 8-item questionnaire with total scores ranging from 0 to 24; higher scores indicate greater daytime sleepiness.
Time frame: From enrollment to the end of treatment at 12 months.
Plan to share: No
Ran from Sep 2022 to primary completion in Aug 2024, 23 months.
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