Original ArticleThe impact of weight reduction in the prevention of the progression of obstructive sleep apnea: an explanatory analysis of a 5-year observational follow-up trial
Highlights
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Obstructive sleep apnea (OSA) is a chronic progressive disease.
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Severe OSA is associated with an increased risk for cardiovascular morbidity and mortality.
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Obesity is the most important risk factor for OSA.
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Weight reduction has been shown to improve OSA, but there is lack of long-term evidence.
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Even a moderate weight reduction can prevent the progression of OSA in 5-year follow-up.
Introduction
Obesity has become an increasing health concern in recent decades. It is now well-known that obesity is associated with increased morbidity and mortality, in particular from cardiovascular and metabolic diseases [1], [2]. Obesity also is the most important risk factor for obstructive sleep apnea (OSA); in fact, most OSA patients (at least 2 out of 3) are obese [3], [4], [5]. OSA is a chronic progressive disease and particularly the more severe stages of OSA have been linked to an increased risk for cardiovascular morbidity and mortality [6], [7]. In the first randomized study conducted on the effects of weight loss on OSA, we demonstrated that a 1-year lifestyle intervention, which included an early weight reduction program, represented a feasible and effective treatment for overweight and obese participants with mild OSA [8]. These findings have been subsequently confirmed by two randomized studies, one conducted in obese OSA patients with type two diabetes mellitus (DM) and the other in patients with moderate to severe OSA using continuous positive airway pressure therapy [9], [10].
Furthermore, our 2-year follow-up study demonstrated that the favorable changes achieved by a supervised lifestyle intervention during the intervention could be sustained for at least 1 year after the discontinuation of the active intervention [11]. In a recent randomized, 5-year, observational, postintervention follow-up study [12], we revealed that supervised lifestyle intervention based weight reduction (i.e., a healthy diet, increased physical activity) represented an effective treatment to prevent the progression of OSA when initiated in early phases of the disorder. These findings were recently supported by another recent long-term follow-up of 3 years [13]. Although these data were encouraging and weight loss is now recommended in all clinical guidelines on OSA, the efficacy of weight reduction as a treatment of OSA may still be underrated by many clinicians. Clinicians commonly believe that any weight loss could be temporary and would return after stopping the active lifestyle counseling; they also believe that this change could result in a re-exacerbation or worsening of OSA in most patients.
The main objective of our report was to extend the assessment of the postinterventional results conducted during the 5-year follow-up regarding the effect of weight loss and physical activity on OSA. To our knowledge, the effect of achieving the weight loss goal and sustaining it for years after the end of actual intervention has not been previously demonstrated. Percentage weight loss provides an easily measured goal for the intervention participants, and the number of participants who achieve a predetermined percentage of weight loss could offer a useful performance indicator for monitoring the efficacy of the intervention. Furthermore, the percentage also is an easily understood goal for the patients while aiming for weight loss. Thus weight loss ⩾5% was the cutoff point we used in our study. We hypothesized that a successful and sustained weight reduction could prevent the progression of OSA.
Section snippets
Methods
Our paper is a detailed and extended secondary analysis of the original 5-year, controlled, randomized, follow-up trial examining the prevention of the progression of OSA [12]. Participants in the intervention group had received a 1-year lifestyle intervention including an initial weight reduction program with 12 weeks on a very low calorie diet. In the control group, only three general dietary and exercise counseling sessions were provided. The design of the study was previously reported in
Results
A total of 81 participants with OSA were originally randomized into our study. The baseline characteristics are shown in Table 1, Table 2. There were no differences in the baseline characteristics between successful and unsuccessful weight loss group (data not shown). Furthermore, there were no differences in the characteristics at baseline, 12-, or 24-month follow-up in individuals who participated in the entire 60-month follow-up compared to those who dropped out earlier (data not shown).
Discussion
Our study provides long-term evidence that sustained weight reduction can result in significant long-term improvements of OSA in overweight patients and can prevent the progression of OSA. In the successful weight reduction group, a marked decrease in the AHI value was achieved from the baseline with every second participant being considered as objectively cured (i.e., they had AHI <5 events per hour). Furthermore, the disease progressed to moderate OSA over the 5-year follow-up in only two
Funding sources
The study was funded by the Hospital District of Northern Savo. Kuopio University Hospital, Yrjö Jahnsson Foundation, Paulo Foundation, Finnish Cultural Foundation, Academy of Finland, Finnish Research Foundation of Otology, Finnish Medical Foundation, Respiratory Foundation and the Finnish Anti-Tuberculosis Foundation have supported the study with grants. The funding sources had no role in study design; collection, analysis, or interpretation of the data; or writing of the report. The
Conflict of interest
The ICMJE Uniform Disclosure Form for Potential Conflicts of Interest associated with this article can be viewed by clicking on the following link: http://dx.doi.org/10.1016/j.sleep.2013.11.786.
Acknowledgments
We cordially acknowledge the members of Kuopio Sleep Apnoea Group Taina Poutiainen, Tomi Laitinen, Tiina Lyyra-Laitinen, Aki Ikonen, Ritva Vanninen, Kari Punnonen, Riitta Pahkala, Erkki Soini and Janne Martikainen.
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