A Two-Year Weight Reduction Program in Obese Sleep Apnea Patients

Obstructive sleep apnea syndrome (OSAS) is a common disorder, in which recurrent episodes of upper airway obstruction during sleep cause repetitive episodes of transient oxygen desaturations. The obstructive apneas cause arousals and other impairments of sleep architecture and are typically associated with excessive snoring and daytime sleepiness.1 OSAS is associated with mood effects and neurocognitive impairments. Further, OSAS is implicated in the pathogenesis of cardiovascular diseases.2 The mechanisms by which OSAS effects the vascular system include intermittent hypoxia, increased sympathetic activation, and endothelial dysfunction.3,4 In addition, there is increasing evidence that obstructive sleep apnea (OSA) is an independent risk factor for insulin resistance, a key contributor to the pathogenesis of cardiometabolic syndrome.5 Obesity and OSAS often covary; 60% to 90 % of OSAS patients have a body mass index (BMI kg/m2) > 28.6 Fat disposition around the pharynx, in the thorax as well as abdomen is considered to be a major cause of OSAS,7,8 and significant sleep apnea is present in about 40% of the severely obese.9,10 Previous studies on weight reduction in obese OSAS patients have shown a reduction of apnea frequency in the short term,11–14 because of decreased upper airway collapsibility15 and increased size of the upper airway passage.16 Compared to surgical intervention, conservative weight reduction involves a smaller risk of morbidity and mortality,17 but is not considered equally successful. In an early non-randomized dietary study, Suratt et al. showed reduced respiratory disturbances after a low calorie diet (LDC) in 8 obese subjects.14 The effect of LCD has been investigated, and complications have been found to be mild and transient.18,19 For OSAS patients there is scant information on the LCD method with regard to long-term effects and results on sleep quality.11 BRIEF SUMMARY Current Knowledge/Study Rationale: Obesity and OSAS most often covary, but conservative weight reduction is difficult to maintain and seldom used. We evaluated the effect of a 2-year program with full-night polysomnography on respiratory disturbances, arousal index, daytime sleepiness, metabolic status and quality of life. Study Impact: Our behavioral change dietary program showed limited success in reducing apnea-hypopnea index. However, the significant improvements in weight, oxygen desaturation index, arousal index and subjective symptoms encourage us suggest the program as an adjunct treatment for well-motivated obese subjects with OSAS. We previously published the results of a randomized controlled pilot study of dietary intervention with LCD for 8 weeks, in which there was reduction of weight and nocturnal desaturations (ODI) in the treatment group compared to the control group.20 We then proceeded with the present intervention study, in this same population of obese OSAS patients. After an initial LCD period, we added behavioral change support for 2 years. A short-term follow-up study after 6 months showed reductions in weight, nocturnal respiratory disturbance, blood pressure, metabolic status, and daytime sleepiness.21 In addition, there were improvements in the arousal index, sleep efficiency, percentage deep sleep, and total wake time. The aim of the present study was to evaluate the effects after 2 years of the intervention program with LCD and behavioral change support on obese OSAS patients. The effects on nocturnal respiration and sleep quality were measured, as well as metabolic status, daytime sleepiness, and quality of life. Our hypothesis was that conservative weight reduction in obese OSAS patients would reduce the apnea-hypopnea index (AHI). The primary outcome of interest was change in AHI. The secondary outcome was change is the arousal index (ArousInd).