Validity and reliability of the screening questionnaire for geriatric depression used in the Mexican Health and Age Study

Objective. To assess the validity and reliability of a geriatric depression questionnaire used in the Mexican Health and Age Study (MHAS). Methods. The study was conducted at the Instituto, Nacional de Ciencias Medicas y Nutricion Salvador Zubiran (INCMNSZ) clinic from May 2005 to March 2006. This depression screening nine-item questionnaire was validated using the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV-TR) (fourth revised version) and Yesavage's 15-item Geriatric Depression Scale (GDS-15) criteria. The instrument belongs to the MHAS, a prospective panel study of health and aging in Mexico. Results. A total of 199 subjects 65 years of age and older participated in the validation process (median age= 79.5 years). MHAS questionnaire result was significantly correlated to the clinical depression diagnosis (p<0.001) and to the GDS-15 score (p<0.001). Internal consistency was adequate (alpha coefficient: 0.74). The cutoff point >= 5/9 points yielded an 80.7% and 68.7% sensitivity and specificity respectively. The fidelity for the test retest was excellent (intra-class correlation coefficient= 0.933). Finally, the Bland and Altman agreement points indicated a difference 0.22 percent points between test retest. Conclusion. The MHAS questionnaire is valid and trustworthy, and allows screening in the research field for the presence of depression in the elderly.