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Abstract:
Background: Anxiety is a frequent condition in patients and in the general population. The aim of this study was to investigate changes in anxiety over time and to test several psychometric properties of the Generalized Anxiety Disorder Screener (GAD-7) from a longitudinal perspective.
Methods: The GAD-7 was included in an examination with two waves, six years apart. The study sample (n = 5355) was comprised of representatively selected adults from the general population with a mean age of 57.3 (SD = 12.3) years.
Results: During the 6-year time interval, anxiety increased significantly from 3.28 ± 3.16 (t1) to 3.66 ± 3.46 (t2). Confirmatory factor analyses proved the longitudinal measurement invariance of the GAD-7. Reliability of the GAD-7 was established both for the cross-sectional and the longitudinal perspective. The test-retest correlation was r = 0.53, and there were no substantial sex or age differences in these coefficients of temporal stability. The mean changes in anxiety were similar for males and females, and there was no linear age trend in the changes measured by the GAD-7. Changes in anxiety over the 6-year period were correlated with changes in satisfaction with life (r = -0.30), bodily complaints (r = 0.31), and the mental component of quality of life (r = -0.48).
Conclusion: The GAD-7 is a suitable instrument for measuring changes in anxiety. Age and gender have only minor significance when interpreting change scores.
