Obesity may alter sleep apnea treatment outcome

By Sally Robertson, B.Sc.Mar 5 2013

Obesity may be a factor in determining the success or failure of treatment in patients with obstructive sleep apnea (OSA), report researchers.

Additionally, obesity may predict patient compliance with continuous airway positive pressure (CPAP) treatment, which is currently thought to be the most effective therapy for patients with moderate-to-severe forms of the condition.

In a study of 297 individuals with OSA, Chae-Seo Rhee (Seoul National University College of Medicine, Korea) and colleagues compared outcomes between nonobese and obese individuals who had been treated with CPAP, surgery (surgical removal of throat tissue) or a mandible advancement device (MAD).

Polysomnography data recorded after treatment revealed that the overall success rates (defined as a more than 50% reduction in the apnea-hypopnea index) of the procedures were 82.8% in the CPAP group, 72.4% in the MAD group, and 44.3% in the surgery group.

As reported in the European Archives of Otorhinolaryngology, the overall success rates did not significantly differ between obese and nonobese patients in any of the treatment groups. In addition, subjective measures of treatment outcomes, such as the Epworth Sleepiness Scale and Pittsburgh Sleep Quality Index, showed no difference between the obese and nonobese patients in any of the treatment groups.

However, the oxygen desaturation index was significantly lower in obese than nonobese patients who were treated with MAD or surgery, but not among those treated with CPAP.

"Some studies have reported that nocturnal oximetry would be helpful for diagnosis of OSA," notes the team. "A review of journals regarding nocturnal oximetry and OSA found that the positive predictive value of nocturnal oximetry proved to be very high."

The team also reports that most (82.1%) patients in the CPAP group had severe OSA and of these patients, those who were not obese were significantly more likely to obtain a successful CPAP than obese individuals. By contrast, the MAD and surgery groups did not show any difference in success rate between moderate and severe OSA patients, according to obesity status.

Interestingly, all obese patients using CPAP showed significantly higher compliance than nonobese individuals at 12 months, at 68.2% versus 41.7%, which may have been due to the presence of comorbidities such as hypertension, hypercholesterolemia, and other cardiovascular disorders, suggest the researchers.

"These patients are concerned with the risks of diseases and have good awareness of disease. Thus, obese people may be willing to use CPAP more frequently than non-obese people from this point of view," they say.

The authors say the relationship between OSA and obesity is complex and OSA treatment requires a multidisciplinary approach.

"Thus, additional research is needed to delineate the difference regarding long-lasting therapeutic success and CPAP compliance in obese patients," they conclude.

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