Lowe et al. (2008) investigated the validity and reliability of the GAD-7. Confirmatory factor analyses substantiated the 1-dimensional structure of the GAD-7. Internal consistency was identical across all subgroups (alpha = 0.89). Intercorrelations with the PHQ-2 and the Rosenberg Self-Esteem Scale were r = 0.64 (P < 0.001) and r = -0.43 (P < 0.001), respectively. As expected, women had significantly higher mean (SD) GAD-7 anxiety scores compared with men [3.2 (3.5) vs. 2.7 (3.2); P < 0.001]. Approximately 5% of subjects had GAD-7 scores of 10 or greater, and 1% had GAD-7 scores of 15 or greater. Norms were developed by Lowe et al. (2008) with a German sample of 5030 subjects (53.6% female) with a mean age (SD) of 48.4 (18.0) years. Interpretation
A raw score (from 0 to 21) is presented as well as a percentile rank based on the Lowe et al. (2008) community sample. Given that females score slightly higher than males, a percentile for each gender is presented – the appropriate gender percentile should be selected for interpretation.