Background: Elevated nasal resistance and obesity predispose to obstructive sleep apnea (OSA). Weight loss has been shown to result in an alleviation of OSA, but its effect on nasal airflow has not been studied.
Methods: This study was a prospective, randomized, controlled study with two parallel groups. A total of 52 adult overweight patients (body mass index [BMI], 28-40 kg/m2) with mild obstructive sleep apnea (apnea-hypopnea index (AHI), 5-15) were randomized into two study groups. The intervention group (n = 26) followed a very low calorie diet with a supervised lifestyle intervention while the control group (n = 26) received routine lifestyle counseling. The changes in BMI, total nasal resistance, total nasal volume, and quality of life scores (Mini Rhinoconjunctivitis Quality of Life Questionnaire, MiniRQLQ) were assessed at baseline and after the intervention at 3 months.
Results: The reduction in BMI in the intervention group was significantly greater than that achieved by patients in the control group (5.4 kg/m2 versus 0.5 kg/m2). Accordingly, AHI was reduced by 3.2 events/hour in the intervention group and by 1.3 in the control group. However, there were no significant changes in rhinometric measurements despite significant weight loss. There was no correlation between the reduction of BMI and the change in nasal resistance or MiniRQLQ scores.
Conclusion: Weight reduction does not seem to have any effect on nasal resistance or volume in overweight patients with mild OSA. Patients with OSA and impaired nasal breathing need specific medical or surgical treatment to restore nasal airflow.
Trial registration: ClinicalTrials.gov NCT00486746.