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In response to uvulopalatopharyngoplasty reduces the incidence of depression caused by obstructive sleep apnea

The questions posed by Binar et al. are very important clinically but beyond the scope of this study. This study was conducted using insurance claims data rather than general clinical data. Therefore, we could obtain information about the patient’s diagnosis, procedure, operation, medication list, and so on, which are required for the claims, but not the clinical information such as the patient’s symptoms or test results. In other words, it was not possible to classify the severity of obstructive sleep apnea (OSA) patients based on apnea-hypopnea index (AHI) or compare the depression symptoms before and after surgery. This was clearly a limitation of this study. However, research using claims data has a great advantage; it allows long-term observation of a large number of patients. The Korea National Health Insurance Corporation covers nearly the entire South Korean population of about 50 million, and the data are well organized. Using the claims data, we performed an observation of an average of 4.6 years with about 20,000 patients who underwent uvulopalatopharyngoplasty (UPPP). So far, there have been no studies on such a large number of UPPP cases. In addition, most studies about UPPP have evaluated the short-term, postoperative effect, usually focusing on AHI reduction. From this point of view, this study is optimal for evaluating the long-term clinical impact of UPPP. A smallscale short-term study as was conducted previously would not have found a reduction in depression after UPPP. UPPP is usually believed to not reduce AHI (and so is not recommended in many guidelines), but numerous studies have shown that AHI decreases after UPPP. According to our recent meta-analysis, UPPP was very effective in patients with large tonsils. Therefore, the claim that UPPP has no effect in reducing AHI is not confirmed, and we are confident that UPPP is certainly effective in some patients. If so, there is a possibility that a decrease in AHI might reduce the incidence of depression. Another plausible hypothesis is that improvement in sleep quality after UPPP might have prevented the occurrence of depression. Symptoms such as daytime drowsiness due to OSA have been reported to be associated with depressive symptoms, and some studies have shown that depression improves after treatment of OSA. However, the exact mechanism by which depression is reduced needs to be studied further.