Plain language summary
Obstructive sleep apnoea (OSA) represents one of the most common and serious sleep-related breathing disorders. Excess body weight has emerged as the strongest modifiable predictor of the onset and severity of OSA. The aim of this study was to explore the dose-response relationship between the degree of weight loss and improvements in OSA severity. This study is a secondary analysis of the Mediterranean diet/lifestyle Intervention for the Management of Obstructive Sleep Apnea (MIMOSA) study, which was designed as a single-centre, single-blind, parallel, randomised, controlled clinical trial. Results show that respiratory events and oximetry indices improved only in patients who lost weight and improvements were proportional to the degree of weight loss. Authors conclude that their findings indicate a dose-response relationship between the degree of weight loss and improvement in OSA severity and symptoms. However, further research is needed to gather more data on the optimal degree of weight loss and appropriate weight-loss interventions for managing the wide spectrum of OSA severity to guide clinical practice.
Expert Review
Conflicts of interest:
None
Take Home Message:
Important from a public health perspective:
- This study has confirmed that even a small degree of weight loss can have a beneficial effect on respiratory events and oxygen desaturation in moderate-to-severe OSA, but clinicians should preferably aim at a ≥ 5% weight loss, and ideally a ≥ 10% weight loss, to achieve clinically meaningful reductions in OSA severity.
Evidence Category:
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X
A: Meta-analyses, position-stands, randomized-controlled trials (RCTs)
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B: Systematic reviews including RCTs of limited number
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C: Non-randomized trials, observational studies, narrative reviews
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D: Case-reports, evidence-based clinical findings
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E: Opinion piece, other
Summary Review:
Introduction
OSA represents one of the most common and serious sleep-related breathing disorders, with a high worldwide prevalence of almost 1 billion people. OSA has numerous well-established cardiometabolic consequences.
The authors highlight that weight loss is essential for obstructive sleep apnea (OSA) management. However, the optimal degree of weight loss for improving OSA severity or eliminating sleep-disordered breathing has not been extensively studied. The aim of this study was to explore the dose-response relationship between the degree of weight loss and improvements in OSA severity.
Methods
This is a secondary analysis of the Mediterranean diet/lifestyle Intervention for the Management of Obstructive Sleep Apnea (MIMOSA) study. This study was designed as a single-center, single-blind, parallel, randomised, controlled clinical trial to evaluate the effectiveness of a weight-loss Mediterranean dietary/lifestyle intervention on managing OSA.
This 6-month long clinical trial included 180 adult, overweight/obese moderate-to-severe OSA patients (45 patients per study group plus a 29% dropout rate). All patients were prescribed the standard of care continuous positive airway pressure (CPAP) therapy and were randomised to 3 arms: standard care; Mediterranean diet; Mediterranean lifestyle
Based on percent change in weight at 6 months, participants were categorised into a weight-stable/gain (WS/GG) group or one of 3 weight-loss groups (WLG): < 5%WLG; 5%–10%WLG; ≥ 10%WLG. Polysomnographic data and OSA symptoms were also evaluated preintervention and postintervention.
Results
Results confirm a dose-response relationship between the degree of weight loss achieved through a dietary/lifestyle intervention and improvements in OSA severity.
- Respiratory events and oximetry indices improved only in patients who lost weight. Improvements were proportional to the degree of weight loss.
- Median percent change in apnea-hypopnea index (AHI) was −11.7%, − 37.9%, and − 49.3% in the < 5%WLG, 5%–10%WLG, and ≥ 10%WLG, respectively (P < .001).
- Compared to the WS/GG, the age-, sex-, baseline-, and CPAP use–adjusted relative risk (95% confidence interval) of severe OSA (AHI ≥ 30 events/h) was 0.45 (0.23–0.87) in the 5%–10%WLG and 0.32 (0.17–0.64) in the ≥ 10%WLG; the risk was also lower in the ≥ 10%WLG vs the < 5%WLG (0.42 [0.22–0.82]).
- Insomnia and daytime sleepiness also improved more in participants exhibiting ≥ 5% weight loss.
- The dose-response relationship between weight loss and improvement in OSA severity was evident regardless of self-reported CPAP use.
Conclusions
The authors conclude that even a < 5% weight loss was sufficient for improvements in respiratory events and oximetry indices, but the prevalence of severe OSA reduced only after a ≥ 5% weight loss, and patients achieving a ≥ 10% weight loss exhibited the greatest benefits compared to weight-stable/gain patients.
Clinical practice applications:
These findings might be useful for Nutritional Therapists and Clinical Practitioners:
- Clinicians should aim for a ≥ 5% weight loss, and ideally a ≥ 10% weight loss, to achieve clinically meaningful reductions in OSA severity.
- Improvements after weight loss were significant even though a healthy body weight was not achieved.
Considerations for future research:
- The study sample consisted of predominantly male, overweight, otherwise healthy patients with moderate-to-severe OSA. Therefore, findings cannot be generalised to the whole OSA population and further research is required with broader, diverse, study samples.
- 6 months is a short duration period, therefore longer trials are required.
- Self-reported CPAP use by participants is a limitation of this study. Further robust analysis methods should be considered for future trials.
- Participants were advised to abstain from CPAP therapy for 2 days prior to the follow-up PSG but this was not evaluated or confirmed in this study and should be in future research.
Abstract
STUDY OBJECTIVES Lifestyle-induced weight loss is a complementary therapeutic approach for obstructive sleep apnea (OSA). We aimed at identifying the dose-response relationship between weight loss and OSA severity improvement. METHODS This is a secondary analysis of a 6-month clinical trial in 180 adult, overweight/obese moderate-to-severe OSA patients. Participants were randomized to a standard care, a Mediterranean diet, or a Mediterranean lifestyle arm. All patients were prescribed with continuous positive airway pressure (CPAP), while intervention arms additionally participated in a weight-loss dietary/lifestyle intervention. Based on percent change in weight at 6 months, participants were categorized into a weight-stable/gain (WS/GG) group or 3 weight-loss groups (WLG): < 5%WLG, 5%-10%WLG, and ≥ 10%WLG. Polysomnographic data and OSA symptoms were evaluated preintervention and postintervention. RESULTS Respiratory events and oximetry indices improved only in patients who lost weight and improvements were proportional to the degree of weight loss. Median percent change in apnea-hypopnea index (AHI) was -11.7%, - 37.9%, and - 49.3% in the < 5%WLG, 5%-10%WLG, and ≥ 10%WLG, respectively (P < .001). Compared to the WS/GG, the age-, sex-, baseline-, and CPAP use-adjusted relative risk (95% confidence interval) of severe OSA (AHI ≥ 30 events/h) was 0.45 (0.23-0.87) in the 5%-10%WLG and 0.32 (0.17-0.64) in the ≥ 10%WLG; the risk was also lower in the ≥ 10%WLG vs the < 5%WLG (0.42 [0.22-0.82]). Insomnia and daytime sleepiness also improved more in participants exhibiting ≥ 5% weight loss. CONCLUSIONS Even a < 5% weight loss can reduce respiratory events, but a ≥ 5% and ideally ≥ 10% weight loss is necessary for reducing the prevalence of severe OSA. CLINICAL TRIAL REGISTRATION Registry: ClinicalTrials.gov; Name: Mediterranean Diet/Lifestyle Intervention in Obstructive Sleep Apnea; URL: https://clinicaltrials.gov/ct2/show/NCT02515357; Identifier: NCT02515357. CITATION Georgoulis M, Yiannakouris N, Kechribari I, et al. Dose-response relationship between weight loss and improvements in obstructive sleep apnea severity after a diet/lifestyle intervention: secondary analyses of the "MIMOSA" randomized clinical trial. J Clin Sleep Med. 2022;18(5):1251-1261.
Methodological quality
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Allocation concealment
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