PSYCHOMETRIC VALIDATION OF THE SPANISH VERSION OF THE GAD-2 SCALE FOR SCREENING GENERALIZED ANXIETY DISORDER

Aim To carry out the psychometric validation of the Spanish version of the 2-items self-administered GAD-2 scale for screening probable patients with Generalized Anxiety Disorder (GAD). Methods The content validity was assessed by inter-ratter-agreement (item-goal congruence index of Rovinelli-Hambleton). The GAD-2 was self-administered to patients with GAD according to DSM IV criteria and their respective controls, matched by age and sex, who were recruited at random in Mental Health and Primary Care centres. Criteria validity was explored using ROC curve analysis, and sensitivity, specificity, predictive positive value and negative value for different cut-off values were determined. Concurrent validity was also explored using the HAM-A, HADS, and WHO-DAS-II scales. Results The study sample consisted of 212 subjects (106 patients with GAD) with a mean age of 50.38 years (SD = 16.76). No items of the scale were left blank. Floor and ceiling effects were negligible. No patients with GAD had to be assisted to fill in the questionnaire. Reliability (internal consistency) was high; Cronbach′α = 0.875. A cut-off point of 3 showed adequate values of sensitivity (91.5%) and specificity (85.8%), with AUC being statistically significant [AUC = 0.934; p 0.001) scales. Conclusion The Spanish version of the GAD-2 scale was shown to have appropriate psychometric properties to promptly detect probable cases of GAD in the Spanish cultural context under conditions of routine clinical practice.