Cross-Cultural Adaptation and Validation of the Beck Depression Inventory (BDI-II) in the Community Otomi of the Mezquital Valley, Mexico

<b>Background:</b> The Beck Depression Inventory Second Edition (BDI-II) is used to assess depression worldwide. In Mexico, the BDI-II Spanish translation is widely used. Despite more than 23 million people being identified as indigenous, there is no empirical evidence on the BDI-II psychometric properties among indigenous languages, including Otomi. Therefore, this study aimed to cross-culturally adapt the BDI-II for the Otomi population and evaluate its psychometric properties. <b>Methods:</b> This cross-sectional instrumental study with non-probability sampling was conducted with 228 participants from the Otomi community. The cross-cultural adaptation of the BDI-II followed Beaton's guidelines for self-report measures: (i) translation, (ii) synthesis, (iii) back translation, (iv) expert committee review, (v) pretesting, and (vi) submission of documentation to the developers. Reliability was assessed using Cronbach's alpha. Exploratory and confirmatory factor analyses were used to determine structural and construct validity. <b>Results:</b> The cross-culturally adapted instrument showed adequate reliability, with a total Cronbach's α of 0.756, comprising 14 items and four factors (with alpha coefficients ranging from 0.505 to 0.633). These factors included three cognitive-affective dimensions and one somatic dimension, which conceptually align with Beck's original model. Confirmatory factor analysis (CFA) presented adequate indices: Comparative Fit Index (CFI) = 0.901, Root Mean Square Error of Approximation (RMSEA) = 0.056, IC_90% [0.028-0.079], and Goodness-of-Fit Index = 0.908, which indicate a balanced and parsimonious fit of the model. <b>Conclusions:</b> The BDI-II is a reliable and culturally valid instrument for measuring depressive symptoms among the Otomi people of the Mezquital Valley.