Obesity(1,2) is a proven risk factor for obstructive sleep apnea (OSA), and it is predictable that various patients who will undergo bariatric surgery (BS) might have the disease.

However, most frequently, patients are not diagnosed with the disease whether they are symptomatic or not. Sur-geons(2) usually examine those patients in order to evaluate the risk of OSA before performing BS and might refer such patients for proper study and treatment.

Duarte and Magalhães-da-Silveira(1) conducted a retrospective study aiming to evaluate and identify which param-eters could predict a higher chance of OSA in that specific population. They also developed a 6-item score that had good accuracy for the diagnosis of moderate and severe OSA.

We understand the limitations of the study; however, we would like to consider some key aspects that need to be taken into account for a proper clinical extrapolation.

First, hypertension(3) is known to be an important factor in the development of OSA.(4) There are widely available data revealing the benefits of BS in blood pressure control. In that study,(1) we found that hypertension was not con-sidered a predictive factor in their group of patients. This might have been due to the fact that patients being treated for hypertension or not were grouped together, which might have influenced the results.

Second, the authors referred that they were not able to address all known comorbidities or other sleep complaints. Considering that the article is about OSA patients awaiting BS, we think that there is a potentially relevant predictive factor that was not fully explored: metabolic syndrome,(4) which is consistently associated with both OSA and BS. We believe that, even if we exclude hypertension, cholesterol levels, and other comorbidities, such as diabetes, the metabolic syndrome might predict OSA and must be taken into account in future studies.

Finally, we know that it is necessary to perform OSA screening in all patients who will undergo this type of surgery, regardless of any score. We do not want to undermine the value or the clinical importance of the NO-OSAS score; however, we question whether there is any advantage to its routine application. Would it change our behavior?

In our opinion, that article(1) demonstrates that it is possible to perceive which subgroups of this specific population are at a higher risk in order to direct our attention to them. However, other important clinical parameters need to be assessed so that its predictive power can be enhanced.

REFERENCES

1. Duarte RL, Magalhães-da-Silveira FJ. Factors predictive of obstructive sleep apnea in patients undergoing pre-operative evaluation for bariatric surgery and referred to a sleep laboratory for polysomnography. J Bras Pneumol. 2015;41(5):440-8. http://dx.doi.org/10.1590/S1806-37132015000000027
2. Selim BJ, Surani SR, Ramar K. Role of preoperative screening for adult patients for obstructive sleep apnea. Hosp Pract (1995). 2014;42(5):100-7. http://dx.doi.org/10.3810/hp.2014.12.1163
3. Torres G, Sánchez-de-la-Torre M, Barbé F. Relationship Between OSA and Hypertension. Chest. 2015;148(3):824-32. http://dx.doi.org/10.1378/chest.15-0136
4. Bonsignore MR, Borel AL, Machan E, Grunstein R. Sleep apnoea and metabolic dysfunction. Eur Respir Rev. 2013;22(129):353-64. http://dx.doi.org/10.1183/09059180.00003413