Cultural adaptation into Spanish of the generalized anxiety disorder-7 (GAD-7) scale as a screening tool

Abstract

Background: Generalized anxiety disorder (GAD) is a prevalent mental health condition which is underestimated worldwide. This study carried out the cultural adaptation into Spanish of the 7-item self-administered GAD-7 scale, which is used to identify probable patients with GAD.

Methods: The adaptation was performed by an expert panel using a conceptual equivalence process, including forward and backward translations in duplicate. Content validity was assessed by interrater agreement. 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). Average completion time was 2'30''. 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. The scale was shown to be one-dimensional through factor analysis (explained variance = 72%). A cut-off point of 10 showed adequate values of sensitivity (86.8%) and specificity (93.4%), with AUC being statistically significant [AUC = 0.957-0.985); p < 0.001]. The scale significantly correlated with HAM-A (0.852, p < 0.001), HADS (anxiety domain, 0.903, p < 0.001), and WHO-DAS II (0.696, p > 0.001).

Limitations: Elderly people, particularly those very old, may need some help to complete the scale.

Conclusion: After the cultural adaptation process, a Spanish version of the GAD-7 scale was obtained. The validity of its content and the relevance and adequacy of items in the Spanish cultural context were confirmed.

Figure 1

Maximum likelihood confirmatory solution of items in the adapted version of the GAD-7 scale. Standardized loadings. Chi-Square = 32.59, df = 14, p-value = 0.00330, RMSEA = 0.080

Figure 2

ROC curve of GAD-7 total score.

Figure 3

Mean and confidence interval (95%) of HAM-A score by severity group according to the GAD-7 scale. Anxiety group according to GAD-7 score; Normal/Minimum (0-7 points), Mild (8-10), Moderate (11-14) and Severe (15-21). p < 0.001 for between-group comparisons in all cases. Diagonal segments are produced by ties.

Figure 4

Mean (95% CI) standardized score of WHO DAS II scale, total and by domain, by group of subjects. GAD = Generalized Anxiety Disorder group; Control = Control group; **p < 0.001.