ABSTRACT
Introduction: Globally, mental health problems have affected nearly 1 billion people and approximately 1 in 10 Mexicans. The detection and surveillance of depression, anxiety, and stress in Mexico requires more reliable and valid instruments. Objective: To determine the factor validity and internal consistency of the Depression, Anxiety, and Stress Scale-21 items (DASS-21) in a non-probabilistic national sample of Mexican adults. Method: Cross-sectional study by means of an online survey of 1 613 Mexican adults aged 18 years and older. The Spanish version of the DASS-21 was used, which evaluates the presence of depressive symptoms, anxiety, and stress. Factor validity was determined by comparing different confirmatory factor analysis models: one-dimensional, three factors (correlated and non-correlated), second or-der, and bifactor. Results: The application of the bifactor model to the DASS 21, supports its validity for identifying the presence of symptoms of depression, anxiety, and stress, as well as an altered general emotional state in a sample of Mexican adults. Conclusions: The DASS-21 is a theoretically robust instrument useful for research and clinical practice. © 2023 Fundación Universitaria Konrad Lorenz.