Shorter Mandibular Length is Associated with a Greater Fall in AHI with Weight Loss

Obesity is a major risk factor towards the development of obstructive sleep apnea, while significant weight loss (both conservatively managed and surgically assisted) has a variable effect upon its severity. Differences in the effect of weight loss on obstructive sleep apnea may be due to underlying craniofacial characteristics. To determine whether craniofacial characteristics can predict OSA treatment response to significant weight loss. We analyzed craniofacial measurements from lateral cephalograms performed at baseline on 57 patients enrolled in a previously reported 2-year randomized clinical weight loss trial (laparoscopic adjustable gastric band surgery versus conservatively [dietician and very low calorie diet] treated). Group mean weight loss was ∼ 13% (mean weight loss 131 to 114 kg), with corresponding reduction in mean apnea-hypopnea index (AHI) from 61 to 41 events/h. Computer assisted lateral cephalogram analysis was undertaken by three trained staff blinded to treatment. We analyzed lateral cephalogram and demographic data at baseline (cross-sectional) and change over two years (interventional) in 54 patients. Baseline cross-sectional analysis indicated no cephalometric measurement correlated significantly with baseline AHI when corrected for neck circumference. The percentage change in AHI over 2 years correlated with a shorter menton-gonion distance (i.e., mandibular body length). The % change in AHI correlated with the % weight change (R(2) = 0.25, p < 0.001) and mandibular body length (R(2) = 0.19, p = 0.002). The % change in AHI correlated with combined weight change and mandibular body length (combined R(2) = 0.31, p < 0.001). Weight loss as a therapeutic option for severe OSA with severe obesity may be predicted by shorter mandibular body length as measured by lateral cephalometry.