Psychometric Properties of the General Anxiety Disorder 7-Item (GAD-7) Scale in a Heterogeneous Psychiatric Sample

Sverre Urnes Johnson, Pål Gunnar Ulvenes, Tuva Øktedalen, Asle Hoffart, Sverre Urnes Johnson, Pål Gunnar Ulvenes, Tuva Øktedalen, Asle Hoffart

Abstract

The GAD-7 is commonly used as a measure of general anxiety symptoms across various settings and populations. However, there has been disagreement regarding the factor structure of the GAD-7, and there is a need for larger studies investigating the psychometric properties of the measure. Patients undergoing treatment (N = 1201), both inpatient and outpatient patients, completed the GAD-7 at pre- and post-treatment. Measures of depression, well-being, and other anxiety measures were also completed, making it possible to investigate convergent and divergent validity. Internal consistency and convergent validity were excellent for the total sample, and there was acceptable variation related to treatment groups. We conducted an exploratory factor analysis (EFA) on a random sample (50%) of the patients at intake and then conducted a confirmatory factor analysis (CFA) to confirm the factor structure in the other part of the sample at intake. The EFA indicated a clear one-factor solution, but the one-factor solution with CFA provided a poor fit to the data. Correlating the residuals among items assessing somatic symptoms led to a good fit in a respecified CFA solution. The GAD-7 has excellent internal consistency, and the one-factor structure in a heterogeneous clinical population was supported.

Keywords: GAD-7; anxiety; assessment; comorbidity; psychometric.

Figures

FIGURE 1
FIGURE 1
One-factor model of the GAD-7. Only significant paths, p = 0.05 are shown. G1, nervous; G2, control of worry; G3, worry; G4, trouble relaxing; G5, restless; G6, irritable; G7, afraid.

References

    1. Akaike H. (1974). A new look at the statistical model identification. IEEE Trans. Autom. Control 19 716–723. 10.1109/TAC.1974.1100705
    1. Beard C., Björgvinsson T. (2014). Beyond generalized anxiety disorder: psychometric properties of the GAD-7 in a heterogeneous psychiatric sample. J. Anxiety Disord. 28 547–552. 10.1016/j.janxdis.2014.06.002
    1. Beck A. T., Epstein N., Brown G., Steer R. A. (1988). An inventory for measuring clinical anxiety: psychometric properties. J. Consult. Clin. Psychol. 56 893–897. 10.1037/0022-006X.56.6.893
    1. Beck A. T., Steer R. A., Brown O. K. (1996). Beck Depression Inventory Manual, 2nd Edn San Antonio. TX: Psychological Corporation.
    1. Brown T. A. (2015). Confirmatory Factor Analysis for Applied Research, 2nd Edn New York, NY: Guilford Press.
    1. Browne M. W., Cudeck R. (1993). “Alternative ways of assessing model fit,” in Testing Structural Equation Models, eds Bollen K. A., Long J. S. (Beverly Hills, CA: Sage; ), 136–162.
    1. Cohen J. (1988). Statistical Power Analysis for the Behavioral Sciences. Cambridge, MA: Academic Press.
    1. Creamer M., Foran J., Bell R. (1995). The beck anxiety inventory in a non-clinical sample. Behav. Res. Ther. 33 477–485. 10.1016/0005-7967(94)00082-U
    1. Dear B. F., Titov N., Sunderland M., McMillan D., Anderson T., Lorian C., et al. (2011). Psychometric comparison of the generalized anxiety disorder scale-7 and the penn state worry questionnaire for measuring response during treatment of generalised anxiety disorder. Cogn. Behav. Ther. 40 216–227. 10.1080/16506073.2011.582138
    1. Derogatis L. R. (1983). The Symptom Checklist -90 Revised: Administration, Scoring and Procedures Manual II. Baltimore, MD: Clinical Psychometric Research.
    1. Derogatis L. R., Savitz K. L. (2000). “The SCL–90–R and brief symptom inventory (BSI) in primary care,” in Handbook of Psychological Assessment in Primary Care Settings, ed. Maruish M. E. (Mahwah, NJ: Lawrence Erlbaum Associates Publishers; ), 297–334.
    1. Gillis M. M., Haaga D. A. F., Ford G. T. (1995). Normative values for the beck anxiety inventory, fear questionnaire, penn state worry questionnaire, and social phobia and anxiety inventory. Psychol. Assess. 7 450–455. 10.1037/1040-3590.7.4.450
    1. Harvey A. G., Watkins E. R., Mansell W., Shafran R. (2004). Cognitive-Behavioral Processes Across Psychological Disorders: A Transdiagnostic Approach to Research and Treatment. Oxford: Oxford University Press.
    1. Hinz A., Klein A. M., Brähler E., Glaesmer H., Luck T., Riedel-Heller S. G., et al. (2017). Psychometric evaluation of the generalized anxiety disorder screener GAD-7, based on a large German general population sample. J. Affect. Disord. 210 338–344. 10.1016/j.jad.2016.12.012
    1. Horn J. L. (1965). A rationale and test for the number of factors in factor analysis. Psychometrica 30 179–185. 10.1007/bf02289447
    1. Hu L. T., Bentler P. M. (1999). Cutoff criteria for fit indexes in covariance structure analysis: conventional criteria versus new alternative. Struct. Equ. Model. 6 1–55. 10.1080/10705519909540118
    1. Johnson S. U., Hoffart A., Nordahl H. M., Wampold B. E. (2017). Metacognitive therapy versus disorder-Specific CBT for comorbid anxiety disorders: a randomized controlled trial. J. Anxiety Disord. 50 103–112. 10.1016/j.janxdis.2017.06.004
    1. Kertz S., Bigda-Peyton J., Bjorgvinsson T. (2013). Validity of the generalized anxiety disorder-7 scale in an acute psychiatric sample. Clin. Psychol. Psychother. 20 456–464. 10.1002/cpp.1802
    1. Kessler R. C., Avenevoli S., McLaughlin K. A., Green J. G., Lakoma M. D., Petukhova M., et al. (2012). Lifetime co-morbidity of DSM-IV disorders in the US national comorbidity survey replication adolescent supplement (NCS-A). Psychol. Med. 42 1997–2010. 10.1002/mpr.1359
    1. Kroenke K., Spitzer R. L., Williams J. B. (2001). The PHQ-9: validity of a brief depression severity measure. J. Gen. Intern. Med. 16 606–613. 10.1046/j.1525-1497.2001.016009606.x
    1. Kroenke K., Spitzer R. L., Williams J. B. W., Monahan P. O., Löwe B. (2007). Anxiety disorders in primary care: prevalence, impairment, comorbidity, and detection. Ann. Intern. Med. 146 317–325. 10.7326/0003-4819-146-5-200703060-00004
    1. Löwe B., Decker O., Müller S., Brähler E., Schellberg D., Herzog W., et al. (2008). Validation and standardization of the generalized anxiety disorder screener (GAD-7) in the general population. Med. Care 46 266–274. 10.1097/MLR.0b013e318160d093
    1. Lykke J., Hesse M., Austin S. F., Oestrich I. (2008). Validity of the BPRS, the BDI and the BAI in dual diagnosis patients. Addict. Behav. 33 292–300. 10.1016/j.addbeh.2007.09.020
    1. Osman A., Kopper B. A., Barrios F., Gutierrez P. M., Bagge C. L. (2004). Reliability and validity of the beck depression Inventory-II With adolescent psychiatric inpatients. Psychol. Assess. 16 120–132. 10.1037/1040-3590.16.2.120
    1. Osman A., Kopper B. A., Barrios F. X., Osman J. R., Wade T. (1997). The beck anxiety inventory: reexamination of factor structure and psychometric properties. J. Clin. Psychol. 53 7–14. 10.1002/(SICI)1097-4679(199701)53:1<7::AID-JCLP2<;2-S
    1. Rutter L. A., Brown T. A. (2017). Psychometric properties of the generalized anxiety disorder scale-7 (GAD-7) in outpatients with anxiety and mood disorders. J. Psychopathol. Behav. Assess. 39 140–146. 10.1007/s10862-016-9571-9
    1. Schmitz N., Hartkamp N., Kiuse J., Franke G. H., Reister G., Tress W. (2000). The symptom check-list-90-R (SCL-90-R): a German validation study. Qual. Life Res. 9 185–193.
    1. Schumacker R. E., Lomax R. G. (2004). A Beginner’s Guide to Structural Equation Modeling. Mahwah, NJ: Lawrence Erlbaum.
    1. Schwarz G. (1978). Estimating the dimension of a model. Ann. Stat. 6 461–464. 10.1214/aos/1176344136
    1. Spitzer R. L., Kroenke K., Williams J. B. W., Löwe B. (2006). A brief measure for assessing generalized anxiety disorder the GAD-7. Arch. Intern. Med. 166 1092–1097. 10.1001/archinte.166.10.1092
    1. Ware J. E., Jr. (1999). SF-36 Health Survey The Use of Psychological Testing for Treatment Planning and Outcomes Assessment, 2nd Edn Mahwah, NJ: Lawrence Erlbaum Associates Publishers, 1227–1246.
    1. Ware J. E., Snow K. K., Kosinski M., Gandek B. (1993). SF-36 Health Survey Manual and Interpretation Guide. Boston: The Health Institute.

Source: PubMed

Sponsorer og samarbejdspartnere

Medicinske tilstande

Narkotikainterventioner

3
Abonner