Objective: Obesity is the main risk factor for obstructive sleep apnea (OSA). While body mass index (BMI) is the most reliable indicator of obesity, it may not fully reflect metabolic status. This study investigated the predictive value of the triponderal mass index (TMI), which better reflects metabolic rate and obesity in both children and adults, for OSA severity.
Materials and Methods: The medical records of 507 adult patients with clinical suspicion of OSA were retrospectively reviewed. After applying exclusion criteria, 487 records were included. Both BMI and TMI were assessed. The relationships of TMI and BMI with the oxygen desaturation index (ODI), minimum oxygen saturation (minSpO2), mean oxygen saturation (meanSpO2), and the apnea-hypopnea index (AHI) were analyzed.
Results: The median BMI was 32.1 (20.0-59.9) kg/m2, and the median TMI was 19.3 (11.4-47.4) kg/m3. A positive correlation was found between median TMI and OSA severity (r=0.218, p<0.001). BMI showed a significant positive correlation with AHI (r=0.2017, p<0.001), and a similarly strong positive correlation was observed between TMI and AHI (r=0.2441, p<0.001). Receiver operating characteristic curve analysis for predicting severe OSA revealed that BMI (cut-off: 31.28) had a sensitivity of 65.57% and specificity of 63.27%, whereas TMI (cut-off: 17.20) demonstrated higher sensitivity (77.05%) but lower specificity (44.39%).
Conclusion: This is the first study to demonstrate that TMI predicts OSA severity in adults. TMI exhibits high sensitivity for identifying severe OSA, whereas BMI provides more balanced specificity. These findings pave the way for further research into the role of OSA in children and the significance of TMI in obesity hypoventilation syndrome.