Clinical Course of Surgical Treatment for Adult Obstructive Sleep Apnea and the Natural Course of Untreated Patients

Objectives: The primary objective of this study was to evaluate the clinical course of adult obstructive sleep apnea after surgical treatment by comparing the natural courses of untreated patients. We aimed to identify factors influencing long-term changes in the apnea-hypopnea index (AHI) and to determine the duration of sustained surgical success. Methods: We retrospectively analyzed 74 adults (43 untreated, 31 surgical groups) with two separate polysomnographies (PSG). The surgical treatment group underwent PSG for pre/post-operative evaluation, while the untreated group underwent re-evaluation due to persistent symptoms. Severity was defined by AHI. Surgical treatment primarily included tonsillectomy and palatal procedures. Outcomes were compared by duration following surgery or no treatment (<36 vs. ≥36 months). Multivariate regression, adjusted for age, evaluated the impact of follow-up duration and body mass index (BMI) changes. Results: In the untreated group, significant AHI deterioration occurred in moderate cases (p=0.025). The surgical treatment group showed significant AHI reduction within 36 months (p=0.001), but AHI rebounded toward baseline after ≥36 months, accompanied by weight gain (p=0.005). Even after adjusting for BMI and age, AHI naturally increased by 0.37/hr per month post-surgery (p=0.001), suggesting a time-dependent decline in efficacy. Conclusion: Surgical treatment offers excellent short-term outcomes, but efficacy diminishes after 3 to 5 yr. Our model predicts surgical benefits are completely offset at 53.6 months, likely due to weight gain and the loss of anatomical support from tonsillectomy. Continuous weight management and regular long-term follow-up are essential for maintaining surgical success.