Thirty-three patients scheduled to undergo LAGB were enrolled in this study. Three patients withdrew prior to the performance of any study-related procedures (one postponed the surgery and two failed to keep the initial appointment). A total of 30 patients (10 males, 20 females) underwent clinical evaluation and polysomnography prior to their laparoscopic procedure, followed by a fasting measurement of leptin and ghrelin. Forty-five percent of the women (n = 9) were postmenopausal. The mean age of the women was 45.4 ± 12.0 years and for men was 41.1 ± 13.8 years. Hypertension was more common in males than in females (70% versus 40%).
After the baseline assessment, six patients failed to keep research appointments and were withdrawn from the final data analysis. There were no statistically significant differences between those patients and the remaining group for comparisons of age, body mass index, or AHI values. The 12-month postoperative visit took place 15.3 ± 4.0 months after the baseline assessment and 14.5 ± 3.2 months after bariatric surgery. A total of 24 patients were evaluated at this endpoint, and comparative data for both time points are shown in .
Vital signs, sleep study parameters, and levels of leptin and ghrelin at baseline and 12 months postoperatively in all patients
Of note, the mean patient body mass index at baseline was 47.2 ± 11.0 kg/m2 (range 34.5–80.5) and was reduced to 35.6 ± 8.2 kg/m2 postoperatively (P < 0.0001), corresponding to a 22.7% ± 7% weight loss, 44.4% ± 14% excess weight lost, and 44.4% ± 16% excess body mass index one year after laparoscopic band insertion. Five patients reduced their body mass index to less than 30 kg/m2 at 12 months postoperatively. Despite weight reduction, there were no statistically significant changes in blood pressure measurements or need for antihypertensive medication between the preoperative period and the 12 month postoperative follow-up. Preoperatively, 20 patients (83.3%) had evidence of OSA (AHI ≥ 5), with a mean AHI of 40.5 ± 35.1 events per hour. The prevalence of OSA was similar between genders [eight of nine males (89%) and 12 of 15 females (80%)]. None of the patients with OSA were actively compliant with continuous positive airway pressure or other modalities of sleep apnea treatment.
At 12 months, there was a marked and statistically significant reduction in all measurements of sleep apnea severity when compared with baseline. Overall, there was a 44% decrease in mean AHI values (34 versus 19 events per hour, P < 0.0001). Resolution of OSA was observed in three patients (all females). The prevalence of severe sleep apnea (AHI ≥ 30 events per hour) decreased from 37.5% to 20% at 12 months postoperatively in this sample. Individual data are shown in .
Individual data points for all patients’ body mass index and apnea-hypopnea index at baseline and 12 months postoperatively, as well as percentage of excess weight loss and change in apnea-hypopnea index at 12 months
Fasting plasma leptin levels were significantly lower 12 months after bariatric surgery as compared with baseline values, consisting of a 31.7% decrease in mean value during this one-year period. There was no statistically significant change in fasting ghrelin levels during the study period.
When analyzed by gender, the overall AHI values were higher in men at both time measurements, as demonstrated in . Significant improvement in AHI was seen at the 12-month postoperative assessment for both genders, but improvement was not statistically significant between the genders. No statistically significant differences were seen for changes in body mass index, leptin, or ghrelin between the genders at 12 months, as demonstrated in .
Boxplots of body mass index, apnea-hypopnea index, and leptin and ghrelin values at baseline and 12 months by gender.
Gender differences in mean respiratory and oxygen parameters during sleep at baseline and 12 months postoperatively
Subdividing the female patients based on menopausal status revealed increased severity of OSA at baseline in the postmenopausal group compared with premenopausal women (34.1 versus 8.7 events per hour, P = 0.001). The baseline rapid eye movement AHI was also significantly higher in the postmenopausal women (84.5 versus 18.9 events per hour, P = 0.002), and this difference remained statistically significant after adjusting for body mass index (P < 0.0001). Among the menopausal women, there was significant improvement in the rapid eye movement sleep-related respiratory events after LAGB, which was not observed among women who were premenopausal.
The severity of OSA did not correlate with body mass index at baseline (r = 0.18, P = 0.40) or 12 months (r = 0.22, P = 0.31). Also, no significant correlation between absolute weight and sleep time spent at oxygen saturation levels below 90% was seen either at baseline (r = 0.07, P = 0.74) or 12 months (r = −0.11, P = 0.60).
Change in leptin over time correlated with changes in body mass index and percentage of excess weight lost in this sample, although they did not reach statistical significance (r = 0.32, P = 0.19 and r = −0.39, P = 0.11). Interestingly, ghrelin levels were strongly and positively correlated with measurements of oxygen saturation during sleep at baseline (r = 0.39, P = 0.07) and at 12 months (r = 0.60, P = 0.01), as demonstrated in .
Relationship between ghrelin levels and mean oxygen saturation during sleep at baseline (left) and 12 months postoperatively (right).