The 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

Abstract

Background

Obstructive sleep apnea (OSA) is a chronic progressive disease, and it is well-documented that severe OSA is associated with an increased cardiovascular morbidity and mortality. Weight reduction has been shown to improve OSA; however, we need further evidence to determine if it may prevent the progression of OSA in the long term. The aim of our study was to assess the impact of weight change during a 5-year observational follow-up of an original 1-year randomized controlled trial.

Methods

The participants were divided into the two groups according to the weight change at 5-year follow-up using the 5% weight loss as a cutoff point, which was later referred to as the successful (n = 20) or unsuccessful groups (n = 27). The change in apnea–hypopnea index (AHI) was the main objective outcome variable.

Results

Fifty-seven patients participated in the 5-year follow-up. At 5 years from the baseline, the change in AHI between the groups was significant in the successful group (−3.5 [95% confidence interval {CI}, −6.1 to −0.9]) compared with the unsuccessful group (5.0 [95% CI, 2.0–8.5]) (P = .002). Successful weight reduction achieved an 80% reduction in the incidence of progression of OSA compared to the unsuccessful group (log-rank test, P = .016).

Conclusions

A moderate but sustained weight reduction can prevent the progression of the disease or even cure mild OSA in obese patients.

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.