Weight reduction found to reduce progression by 80%
Obstructive sleep apnea (OSA) is a disorder in which breathing is briefly and repeatedly interrupted during sleep. More than 18 million adults have sleep apnea. OSA can cause complications including sudden drops in blood oxygen levels that occur during obstructive sleep apnea increase blood pressure and strain the cardiovascular system. Many people with OSA also have hypertension which raises the risk for heart disease. OSA can also cause mood and memory problems and increases the risk of drowsy driving. Certain factors can put you at an increased risk for the disorder including being overweight, having a recessed chin, small jaw or a large overbite, a large neck size (17 inches or greater in a man, or 16 inches or greater in a woman).
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.
Dr. Henri Tuomilehto, MD, PhD, Adjunct Professor at the Institute of Public Health and Clinical Nutrition, University of Eastern of Finland and corresponding author of this study conducted at Kuopio University Hospital, Finland, in collaboration with the University of Eastern Finland between 2004 and 2013. The research team examined the impact of weight change during a 5-year observational follow-up of an original 1-year randomized controlled trial.
This study included moderately obese adults with mild OSA. A total of 81 participants with OSA were originally in the study, 57 participants completed the five year follow-up.
The participants underwent either a 12-month supervised lifestyle intervention program that included dietary counseling to reduce dietary fat to <30% of total energy and to increase the intake of fruits, vegetables, poultry, fish, and lean meat; they also needed to limit the consumption of dairy fats, fatty meats, and desserts. They also received recommendations to to increase their overall level of daily physical activity and endurance exercise, such as walking, skiing, jogging, or swimming. The frequency of physical activity of the participants was self-reported at the follow-up visits.
The participants in the control group were only given standard care consisting of general verbal and written information about diet and physical activity at the baseline, 3-month, and 12-month follow-ups by the study nurse and physician without any specific individualized advice.
During the next 4 years, no intervention or advice was offered to either group including at the 24-month follow-up. The study nurse regularly checked that the participants did not receive any co-intervention for OSA other than that specified in the study design.
The majority of participants (65%) who were considered successful in achieving and sustaining weight reduction throughout the 5 years belonged to the lifestyle intervention group. The average AHI (apnea-hypopnea index; the number of apnea-hypopnea events per hour) at the 5-year follow-up was 6.3 events per hour in the participants with successful weight reduction and 14.6 in those with unsuccessful weight reduction.
There was a statistically significant difference in the mean change of AHI during the follow-up between the successful and unsuccessful group. The originally mild OSA was objectively cured in 50% of participants in the successful weight reduction group, compared to only 11% in those with unsuccessful weight reduction.
Over the entire 5-year follow-up period, OSA had progressed from mild to moderate in only 2 participants in the successful weight reduction group but in 13 participants (and severe OSA in 2 participants) with unsuccessful weight reduction.
The researchers write “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 2 participants. In the unsuccessful weight reduction group, there was a significant increase (>50%) in the mean AHI, and the disease progressed in 15 of 37 participants. Overall, a successful weight loss reduced the risk for the progression of OSA by 80%. In addition to the improvement in AHI, significant improvements from baseline also were found in the symptoms related to OSA, as well as in the key cardiometabolic parameters during the follow-up period.”
Limitations of the study included because the lifestyle intervention included both dietary and healthy lifestyle counseling and increased physical activity and the sample size was relatively small, it is difficult to differentiate between the impacts of the different components of the lifestyle changes. Another limitation was that the study was conducted in participants with mild OSA therefore, the findings may not be directly generalizable to all OSA patients.
This follow-up study is published in Sleep Medicine.