Changes in Body Fat and Morphologic Characteristics Associated With OSA Resolution After Bariatric Surgery

Investigators are concerned about the high prevalence of Obstructive Sleep Apnoea syndrome (OSA) in the bariatric population. Postoperatively, there is a high rate of recovery from OSA. Indeed, investigators know from previous reports that weight loss is a very effective, but time consuming, strategy for treating OSA. Patients are therefore treated with CPAP (Continuous Positive Airway Pressure) while waiting for weight loss. In a recent meta-analysis, which focused on the effect of weight loss achieved through lifestyle interventions in 618 overweight and obese patients, the apnea-hypopnea index (AHI) decreased by an amount of 16/h for an average weight loss of 14 kg (1). However, the majority of patients are not able to maintain weight loss in the long term, and weight gain is associated with recurrence/aggravation of OSAS (2). Nowadays, bariatric surgery is a common strategy to achieve sustained and significant weight loss in obese patients. Sarkhosh et al. examined the impact of bariatric surgery (restrictive procedures, with a mild malabsorption component, or largely malabsorptive procedures) on sleep apnoea in 13,900 patients. Depending on the procedure, improvement or resolution of OSAS was achieved in 78-90% of patients (3).

Prospective longitudinal postoperative follow-up study : inclusion of patients who had scheduled bariatric surgery, diagnosed with OSA, AHI \> 15 (polysomnography), treated with self-controlled CPAP (APAP), under remote monitoring;

Baseline measures:

1. Anthropometric characteristics: body mass index (BMI), neck circumference, waist/hip ratio, fat mass + lean mass (bioelectrical impedance measurements), 2. APAP treatment characteristics, mean APAP pressure, 95th percentile APAP pressure, APAP adherence.

Follow-up:

1. The 2-month follow-up: body mass index (BMI), neck circumference, waist/hip ratio, fat mass + fat-free mass (bioelectrical impedance measurements), mean APAP pressure, 95th percentile APAP pressure, APAP adherence. To assess potential regression of OSA with weight loss: home polygraphy after 4 nights off APAP (4). 2. Six-month and 12-month follow-up: same as at 2 months. Follow-up stops in case of a polygraph showing an AHI \<10, allowing APAP treatment to be stopped.

• Comparison of (1) the correlation between neck circumference reduction and OAS resolution and (2) the correlation between neck circumference reduction and BMI reduction [Time frame: 2 months]
• Comparison of (1) the correlation between neck circumference reduction and OAS resolution and (2) the correlation between neck circumference reduction and BMI reduction [Time frame: 6 months]
• Comparison of (1) the correlation between neck circumference reduction and OAS resolution and (2) the correlation between neck circumference reduction and BMI reduction [Time frame: 12 months]
• Comparison of (1) the correlation between hip circumference reduction and OAS resolution and (2) the correlation between hip circumference reduction and BMI reduction [Time frame: 2 months]
• Comparison of (1) the correlation between hip circumference reduction and OAS resolution and (2) the correlation between hip circumference reduction and BMI reduction [Time frame: 6 months]
• Comparison of (1) the correlation between hip circumference reduction and OAS resolution and (2) the correlation between hip circumference reduction and BMI reduction [Time frame: 12 months]
• Comparison of (1) the correlation between lean mass reduction and OAS resolution and (2) the correlation between lean mass reduction and BMI reduction [Time frame: 2 months]
• Comparison of (1) the correlation between lean mass reduction and OAS resolution and (2) the correlation between lean mass reduction and BMI reduction [Time frame: 6 months]
• Comparison of (1) the correlation between lean mass reduction and OAS resolution and (2) the correlation between lean mass reduction and BMI reduction [Time frame: 9 months]