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Open Access Research

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

Javier García-Campayo12*, Enric Zamorano3, Miguel A Ruiz45, Antonio Pardo45, María Pérez-Páramo6, Vanessa López-Gómez6, Olga Freire7 and Javier Rejas7

Author Affiliations

1 Department of Psychiatry, Hospital Universitario Miguel Servet, Zaragoza, Spain

2 ISCIII- REDIAPP, Red de Investigación en Actividades Preventivas y Promoción de la Salud, Zaragoza, Spain

3 Sant Antoni de Vilamajor Primary Care Health Center, ABS Alt Mogent, Barcelona, Spain

4 Department of Methodology, School of Psychology, Universidad Autónoma de Madrid, Madrid, Spain

5 EACCOS Research Group, Madrid, Spain

6 Neuroscience Department, Medical Unit, Pfizer Spain, Alcobendas (Madrid), Spain

7 Health Outcomes Research Department, Medical Unit, Pfizer Spain, Alcobendas (Madrid), Spain

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Health and Quality of Life Outcomes 2010, 8:8  doi:10.1186/1477-7525-8-8

Published: 20 January 2010

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.