Obstructive sleep apnea/hypopnea (OSAH) is a common chronic disease that is associated with daytime sleepiness, impaired quality of life (QOL), and increased risk of hypertension and cardiovascular disease. The most common treatment is continuous positive airway pressure (CPAP), although adherence to CPAP is poor in more than one-third of patients. Weight loss can clearly lessen the severity of OSAH; although short-term dietary weight loss can often be achieved, it is difficult to maintain. Regular aerobic exercise is associated with a lower prevalence of OSAH in observational studies after adjustment for body habitus, and in two small clinical trials moderate exercise was associated with a substantial decrease in OSAH severity despite little or no weight loss. Demonstrating that dietary weight loss and moderate physical activity, promoted in the home setting, independently improve OSAH severity may have a major impact on the therapeutic approach to OSAH, a disease that is highly prevalent in the VA population.
The specific objectives were to determine the effects on OSAH severity, daytime sleepiness, and quality of life (QOL) of (1) six months of moderate-intensity physical activity promotion via a smartphone application, and (2) six months of dietary weight loss promotion via a smartphone application. Furthermore, we determined the effect of the physical activity promotion intervention on physical activity and the effect of the weight loss promotion intervention on body mass index. A secondary objective was to determine the impact of these interventions on regional fat distribution and upper airway dimensions, which are proposed mediators of the effect of the interventions on OSAH. We hypothesized that both moderate-intensity physical activity and dietary weight loss would independently reduce OSAH severity and daytime sleepiness, and improve QOL.
The project was a randomized, controlled trial designed to test the independent effects of the physical activity and diet interventions, as compared with an attention control intervention. One hundred sixty-nine patients (mean age, 59.5) who met entry criteria (body mass index over 24 kg/m2, physician diagnosis of OSAH, and apnea-hypopnea index > 10/hr) were enrolled and randomly assigned to one of four parallel intervention groups: physical activity and diet (n=43), physical activity alone (n=46), diet alone (n=42), or neither (attention control, n=38). The physical activity intervention involved automated coaching and monitoring activity in real time using smartphone technology and a Polar chest strap (wireless heart rate signal transmission). The diet intervention involved tracking weight and dietary intake over time using smartphone technology (wireless weight value transmitted from Tanita scale to smartphone) with comparisons made to individualized goals. The interventions lasted 6 months.
We examined the potential effects using two-factor (physical activity, weight loss) analysis of variance, with an initial test of interaction. This is a very concise approach that can be beneficial when the response has constant variance for all factor settings. Analyses to test for interaction showed that there was no evidence of interaction with regard to the outcomes of OSAH severity, daytime sleepiness, and QOL, and the inspected residuals for the constant variance assumption indicated that this assumption was satisfied with regard to the three outcomes.
Using two-factor analysis of variance without an interaction, there was no significant effect of either the physical activity intervention or the dietary weight loss intervention on change in OSAH severity, as assessed by the apnea-hypopnea index. The dietary intervention was significantly (p=0.001, N=159) related to reduced sleepiness, as assessed by the Epworth Sleepiness Scale. The physical activity intervention was of borderline significance (p=0.068, N=159) in relation to reduced sleepiness. In addition, there were significant associations of the dietary intervention (p=0.038, N=159) and physical activity intervention (p=0.024, N=159) with improved OSAH-related QOL, as assessed by the Functional Outcomes of Sleep Questionnaire.
Further analyses evaluated the effects of the physical activity promotion intervention on moderate physical activity and the effect of the weight loss promotion intervention on body mass index (BMI). Using analysis of variance, the physical activity intervention was significantly (p=0.009, N=155) related to increase in moderate physical activity, as assessed by 7-day accelerometry. There was a trend (p=0.13, N=155) for the relationship of the dietary intervention with a decrease in BMI.
OSAH is a highly prevalent condition in the VA population that is associated with daytime sleepiness and impaired OSAH-related quality of life (QOL). The most common treatment is continuous positive airway pressure (CPAP), although adherence to CPAP is poor in more than one-third of patients. Our findings demonstrated that the dietary and physical activity interventions, using easily administered telehealth applications in the home setting, improved OSAH outcomes. In particular, patients had a significant reduction in daytime sleepiness and an improvement in OSAH-related QOL. These results will likely have a major impact on the therapeutic approach to OSAH. These interventions have the advantage of low cost and easy dissemination and can be incorporated into the care of patients with OSAH throughout the VA system, in turn, enhancing access to treatment and optimizing care.
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Grant Number: I01HX000120-01A1
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