Functional Capacity, Sleep Quality, and Cognitive Function in Obesity Hypoventilation Syndrome

NCT07147153 | Recruiting

• 1 other identifier: E-29624016-050.99-3179056
• Study Type: observational
• Target: 36
• Locations: 1 country
• Sites: 1

Brief Summary

Introduction: Obesity Hypoventilation Syndrome (OHS) is defined as the coexistence of obesity (BMI ≥ 30 kg/m²), daytime hypercapnia (PaCO₂ \> 45 mmHg) in the absence of other causes of hypoventilation, and sleep-disordered breathing. OHS represents the most severe form of obesity-related respiratory failure and leads to serious consequences such as increased mortality rates, chronic heart failure, pulmonary hypertension, and hospitalisations due to acute or chronic hypercapnic respiratory failure. Aim: The aim of this study is to evaluate cognitive functions in individuals with OHS and to investigate the relationship between cognitive functions, sleep quality, and functional capacity. A review of the literature indicates that cognitive functions in OHS have not been sufficiently examined, and existing studies mainly focus on cognitive impairment in individuals with obstructive sleep apnea syndrome (OSAS). However, OHS may also cause cognitive deficits, and therefore, patients should be assessed from this perspective. Cognitive impairment may negatively affect participation in pulmonary rehabilitation programs and reduce the benefits gained from such programs. Moreover, psychological conditions such as depression and anxiety may also influence the success of pulmonary rehabilitation. Thus, identifying cognitive impairment and its association with parameters such as functional capacity and sleep quality is of great importance. Early detection of cognitive deficits may provide positive outcomes for both patients and the healthcare system. Methods: The study will include 18 individuals with OHS diagnosed by a pulmonologist through polysomnographic evaluation at the Department of Pulmonology, Istanbul University, Istanbul Faculty of Medicine, along with 18 age- and sex-matched individuals with simple obesity (BMI \>30 kg/m²). All participants will be evaluated at the Department of Pulmonology, Istanbul University, Istanbul Faculty of Medicine. Body composition will be assessed using bioelectrical impedance analysis with the "Tanita BC-545N Body Composition Monitor." Functional exercise capacity will be evaluated with the Incremental Shuttle Walk Test (ISWT) and the Six-Minute Walk Test (6MWT). Cognitive functions and attention will be assessed using the Montreal Cognitive Assessment (MoCA) and the Visual Reaction Time Test. Daytime sleepiness will be measured with the Epworth Sleepiness Scale (ESS), while sleep quality will be evaluated with the Pittsburgh Sleep Quality Index (PSQI). Psychological status will be assessed using the Depression Anxiety Stress Scale (DASS-21). Statistical analyses will be conducted using the Statistical Package for Social Sciences (SPSS, version 21.0). Arithmetic mean, standard deviation (SD), and confidence intervals (CI) will be presented in tables and figures. The Shapiro-Wilk test will be applied to assess the normality of data distribution. For comparisons between the OHS and simple obesity groups, the Independent Samples T-Test will be used for normally distributed data, while the Mann-Whitney U test will be used for non-normally distributed data. Pearson or Spearman correlation analyses will be performed to investigate the relationship between functional capacity, sleep quality, and cognitive functions.

Conditions

Obesity Hypoventilation Syndrome (OHS)

Keywords

obesity; hypoventilation syndrome; cognitive functions

Outcome Measures

Primary Outcomes (2)

• Incremental Shuttle Walk Test (ISWT)

  The ISWT is a field test consisting of 12 levels in which walking speed increases progressively. Participants are required to walk back and forth between two cones placed 10 meters apart, performing at their maximal capacity until symptom limitation. The test will be terminated if the patient is unable to maintain the required pace due to dyspnea, upon reaching maximal heart rate, or if the participant is more than 0.5 m behind the cone at the designated signal. The number of completed shuttles will be recorded, along with pre- and post-test measurements of blood pressure, heart rate, oxygen saturation, and dyspnea and leg fatigue scores using the Modified Borg Scale.

  At baseline (immediately after informed consent)

• Montreal Cognitive Assessment (MoCA)

  Cognitive functions including selective and sustained attention, information processing speed, short-term memory, and reaction time will be evaluated using standardized tests. To minimize environmental influences, all assessments will be conducted under identical conditions-in a quiet room with consistent physical settings-at the same time of day and by the same researchers for each participant. The MoCA will be used as a cognitive screening tool. It evaluates executive functions, attention and concentration, memory, language, abstract thinking, visuospatial skills, orientation, and calculation. The test takes approximately 10 minutes, and scores are calculated out of 30. A cutoff score of 26 is used; scores below this threshold indicate mild cognitive impairment.

  At baseline (immediately after informed consent)

Secondary Outcomes (5)

• Six-Minute Walk Test (6MWT)

  At baseline (immediately after informed consent)

• Visual Reaction Time

  At baseline (immediately after informed consent)

• Epworth Sleepiness Scale (ESS)

  At baseline (immediately after informed consent)

• Pittsburgh Sleep Quality Index (PSQI)

  At baseline (immediately after informed consent)

• Depression Anxiety Stress Scale (DASS-21)

  At baseline (immediately after informed consent)

Study Arms (2)

Group ı

Individuals diagnosed with Obesity Hypoventilation Syndrome by a pulmonologist based on polysomnography results.

Group II

Individuals with simple obesity (BMI \>30 kg/m²), comparable to Group 1 in terms of age and sex, who had an Apnea-Hypopnea Index (AHI) \<5 on polysomnography or a STOP-Bang score \<3.

Eligibility Criteria

• Age: 18 Years - 65 Years
• Sex: all
• Healthy Volunteers: No
• Age Groups: Adult (18-64), Older Adult (65+)
• Sampling Method: Probability Sample

Study Population

Individuals with Obesity Hypoventilation Syndrome who applied to the Department of Pulmonary Diseases at Istanbul University Istanbul Faculty of Medicine, met the inclusion criteria for the study, and were diagnosed through polysomnographic evaluation by a Pulmonary Disease specialist.

You may qualify if:

• Age between 18 and 65 years
• Diagnosed with OHS by a pulmonologist
• For individuals with simple obesity: BMI between 30 and 40 kg/m², Apnea-Hypopnea Index (AHI) \< 5 on polysomnography, or STOP-Bang score \< 3
• Ability to communicate in written and spoken Turkish

You may not qualify if:

• Presence of any additional severe respiratory disease
• Presence of orthopedic, neurological, cardiovascular, or respiratory conditions preventing exercise testing
• For individuals with simple obesity: presence of OSAS risk factors such as severe snoring or witnessed apnea
• Presence of any psychological or psychiatric disorder that could affect cognitive functions

Sponsors & Collaborators

• Bezmialem Vakif University: lead
• Istanbul University: collaborator

Study Sites (1)

Istanbul University, Istanbul Faculty of Medicine

Istanbul, Turkey (Türkiye)

RECRUITING

Related Publications (12)

• Argun Baris S, Tuncel D, Ozerdem C, Kutlu H, Onyilmaz T, Basyigit I, Boyaci H, Yildiz F. The effect of positive airway pressure therapy on neurocognitive functions, depression and anxiety in obesity hypoventilation syndrome. Multidiscip Respir Med. 2016 Oct 11;11:35. doi: 10.1186/s40248-016-0071-2. eCollection 2016.

  PMID: 27766147 RESULT

• Kielb SA, Ancoli-Israel S, Rebok GW, Spira AP. Cognition in obstructive sleep apnea-hypopnea syndrome (OSAS): current clinical knowledge and the impact of treatment. Neuromolecular Med. 2012 Sep;14(3):180-93. doi: 10.1007/s12017-012-8182-1. Epub 2012 May 9.

  PMID: 22569877 RESULT

• Ranzini L, Schiavi M, Pierobon A, Granata N, Giardini A. From Mild Cognitive Impairment (MCI) to Dementia in Chronic Obstructive Pulmonary Disease. Implications for Clinical Practice and Disease Management: A Mini-Review. Front Psychol. 2020 Feb 28;11:337. doi: 10.3389/fpsyg.2020.00337. eCollection 2020.

  PMID: 32184750 RESULT

• Pierobon A, Sini Bottelli E, Ranzini L, Bruschi C, Maestri R, Bertolotti G, Sommaruga M, Torlaschi V, Callegari S, Giardini A. COPD patients' self-reported adherence, psychosocial factors and mild cognitive impairment in pulmonary rehabilitation. Int J Chron Obstruct Pulmon Dis. 2017 Jul 18;12:2059-2067. doi: 10.2147/COPD.S133586. eCollection 2017.

  PMID: 28790808 RESULT

• Sharafkhaneh A, Giray N, Richardson P, Young T, Hirshkowitz M. Association of psychiatric disorders and sleep apnea in a large cohort. Sleep. 2005 Nov;28(11):1405-11. doi: 10.1093/sleep/28.11.1405.

  PMID: 16335330 RESULT

• Andreou G, Vlachos F, Makanikas K. Effects of chronic obstructive pulmonary disease and obstructive sleep apnea on cognitive functions: evidence for a common nature. Sleep Disord. 2014;2014:768210. doi: 10.1155/2014/768210. Epub 2014 Feb 6.

  PMID: 24649370 RESULT

• McNicholas WT, Hansson D, Schiza S, Grote L. Sleep in chronic respiratory disease: COPD and hypoventilation disorders. Eur Respir Rev. 2019 Sep 25;28(153):190064. doi: 10.1183/16000617.0064-2019. Print 2019 Sep 30.

  PMID: 31554703 RESULT

• Olaithe M, Bucks RS, Hillman DR, Eastwood PR. Cognitive deficits in obstructive sleep apnea: Insights from a meta-review and comparison with deficits observed in COPD, insomnia, and sleep deprivation. Sleep Med Rev. 2018 Apr;38:39-49. doi: 10.1016/j.smrv.2017.03.005. Epub 2017 Mar 30.

  PMID: 28760549 RESULT

• Spira AP, Chen-Edinboro LP, Wu MN, Yaffe K. Impact of sleep on the risk of cognitive decline and dementia. Curr Opin Psychiatry. 2014 Nov;27(6):478-83. doi: 10.1097/YCO.0000000000000106.

  PMID: 25188896 RESULT

• Dusgun ES, Aslan GK, Abanoz ES, Kiyan E. Respiratory Muscle Endurance in Obesity Hypoventilation Syndrome. Respir Care. 2022 May;67(5):526-533. doi: 10.4187/respcare.09338. Epub 2022 Mar 22.

  PMID: 35318239 RESULT

• Iftikhar IH, Roland J. Obesity Hypoventilation Syndrome. Clin Chest Med. 2018 Jun;39(2):427-436. doi: 10.1016/j.ccm.2018.01.006.

  PMID: 29779600 RESULT

• Mokhlesi B, Masa JF, Brozek JL, Gurubhagavatula I, Murphy PB, Piper AJ, Tulaimat A, Afshar M, Balachandran JS, Dweik RA, Grunstein RR, Hart N, Kaw R, Lorenzi-Filho G, Pamidi S, Patel BK, Patil SP, Pepin JL, Soghier I, Tamae Kakazu M, Teodorescu M. Evaluation and Management of Obesity Hypoventilation Syndrome. An Official American Thoracic Society Clinical Practice Guideline. Am J Respir Crit Care Med. 2019 Aug 1;200(3):e6-e24. doi: 10.1164/rccm.201905-1071ST.

  PMID: 31368798 RESULT

MeSH Terms

Conditions

Obesity Hypoventilation Syndrome; Obesity

Condition Hierarchy (Ancestors)

Sleep Apnea, Obstructive; Sleep Apnea Syndromes; Apnea; Respiration Disorders; Respiratory Tract Diseases; Hypoventilation; Respiratory Insufficiency; Sleep Disorders, Intrinsic; Dyssomnias; Sleep Wake Disorders; Nervous System Diseases; Overweight; Overnutrition; Nutrition Disorders; Nutritional and Metabolic Diseases; Body Weight; Signs and Symptoms; Pathological Conditions, Signs and Symptoms

Central Study Contacts

Ayca Arslanturk-Yildirim, Msc

CONTACT

+905312891352; ayca.arslanturk@bezmialem.edu.tr

Study Design

• Study Type: observational
• Observational Model: COHORT
• Time Perspective: CROSS SECTIONAL
• Sponsor Type: OTHER
• Responsible Party: SPONSOR

Study Record Dates

• First Submitted: August 19, 2025
• First Posted: August 28, 2025
• Study Start: January 1, 2025
• Primary Completion: September 30, 2025
• Study Completion: October 15, 2025
• Last Updated: August 28, 2025

Record last verified: 2025-08

Locations

TU (1)