nical data such as the Epworth Sleepiness Score and/or specific radiological examinations. These models have proved difficult to implement, at least to some extent because the description of the anatomical regions involved has not been uniform.23-26
Several studies have shown a statistical relationship between certain morphological abnormalities and OSAS severity. Tonsil size9,27,28 and cervical perimeter27,28 seem to be related to OSAS severity, although their specific weight in the pathophysiological mechanisms of the disease is not clear. The Mallampati score seems to be the only parameter that is strongly related to OSAS severity,9,27,29-33 but there seem to be certain racial variations, with Asians scoring higher for both Mallampati score and OSAS severity32,33 than white participants.
Our study corroborated the results in the literature referring to the association of AHI with age, sex, BMI, and cervical perimeter.27,29 However, our multiple regression analysis showed that all these variables had a low weight for predicting OSAS severity, with the FTP score emerging as the main predictor. Sex and BMI did not significantly contribute to the prediction model, whereas age and the cervical perimeter jointly explained 1.6% of the log AHI variation (see partial R2 values in Table 4). We also considered a uvula score and performed a rhinomanometry to explore their potential usefulness as predictors. The FL150 explained only 0.9% of the log-AHI variation (Table 4), and the uvula score did not significantly improve the prediction.
The low contribution of the nasal flow to the model suggests that the degree of nasal obstruction has a negligible influence on the pathophysiological mechanisms of the disease. These results question the usefulness of grades A and B in Fujita's classification.34 Interestingly, the cervical perimeter shows the second largest R2 value, which may point to obesity as a risk factor (BMI was also significantly correlated with AHI but did not enter the model, possibly because cervical perimeter is more specific as a measure of local obesity).
Similarly, TS was irrelevant. Curiously, tonsillectomy performed during childhood did not seem to be preventive but in fact seemed to favor the development of OSAS (Figure 4).
Previous studies have shown a statistical relationship between the FTP (frequently called the modified Mallampati score) and sleep disturbances.9,27,29-33 To our knowledge, our study is the first to quantify the specific weight of these maneuvers in a multivariate regression model. Our results suggest that a patient with an FTP score of 3 or 4 is unlikely to have an AHI value within the normal range. In other words, findings from a correct oropharyngeal physical examination may contradict those from a sleep study considered to be normal. The strength of the association between the FTP scores and the OSAS severity is further illustrated in Figure 3, in which we show the joint distribution of FTP scores and AHI values categorized according to the AASM criteria.12 Note that all patients with an FTP score of 4 had severe OSAS; most of the patients with an FTP scores of 3 (71.6%) also had severe OSAS, and all the remaining patients but 1 had moderate OSAS. Almost all patients with an FTP score of 2 were evenly split between mild and moderate categories, with only 2 cases (1.7%) being normal and 4 cases (3.5%) being severe. Finally, patients with an FTP score of 1 had either normal or mild OSAS but very rarely moderate and hardly ever severe OSAS.
The FTP score is a modification of the Mallampati score, established by Friedman.9 Mallampati et al35 determined that the position of the palate with respect to the tongue was an indicator of the ease or difficulty of endotracheal intubation. Friedman et al9 definitively related the position of the palate and the tongue with the risk of OSAS. Friedman et al9 made changes to Mallampati's procedure: whereas Mallampati et al35 performed the examination with the tongue outside the oropharyngeal cavity, Friedman et al9 maintained the tongue inside the oral cav