Lack of association between the Friedman's tongue position type IV and obstructive sleep apnea in older adults of Amerindian ancestry

Background: The burden of obstructive sleep apnea (OSA) in rural settings is unknown. In these regions, devices needed for OSA diagnosis are not available, and mass screening with field instruments may be complicated due to cross-cultural factors and illiteracy. The association between the Friedman's tongue position (FTP) and OSA has been assessed in people from different ethnic groups but not in Amerindians. Objective: We aimed to assess whether a FTP type IV is associated with OSA severity and with the apnea-hypopnea index (AHI) in community-dwelling older adults of Amerindian ancestry living in rural Ecuador. Methods: A total of 201 Atahualpa residents aged ≥60 years, who underwent tongue position assessment, brain MRI, and polysomnography were included. After adjusting for relevant confounders, ordinal logistic regression models were fitted to assess the association between the presence of a FTP type IV and OSA categories (none, mild, and moderate-to-severe), and generalized linear models with a Gaussian link were fitted to assess the association between the presence of a FTP type IV and the continuous AHI. Results: A FTP type IV was identified in 153 (76%) individuals, the mean AHI per hour was 11.9 ± 12.4, and 49 (24%) individuals had moderate-to-severe OSA, 88 (44%) had mild OSA, and the remaining 64 (32%) had no OSA. Fully-adjusted generalized linear models showed no independent association between the investigated exposure and the AHI (β: 0.09; 95% C.I.: -1.56 - 1.76; p=0.909). Likewise, ordinal logistic regression models showed no independent association between the investigated exposure and categories of OSA (β: 0.42; 95% C.I.: -0.47 - 1.31; p=0.357). Conclusion: A FTP type IV is not associated with the AHI or the severity of OSA in this population of Amerindians. This lack of association could be related to phenotypic characteristics of people from this ethnic group (mostly their elliptic hard palate).