Psychometric properties and measurement invariance of the 7-item General Anxiety Disorder scale (GAD-7) in an Italian coronary heart disease population

Background: Generalized Anxiety Disorder is predominant in coronary heart disease (CHD) patients. 7-item Generalized Anxiety Disorder (GAD-7) scale psychometric properties have never been tested in CHD populations. This study aims to verify the GAD-7 psychometric properties and measurement invariance in an Italian CHD sample. Method: A baseline data secondary analysis from HEARTS-IN-DYADS study. Several healthcare facilities enrolled an adult inpatient sample. Anxiety and depression data were collected using GAD-7 and Patient Health Questionnaire 9 (PHQ-9). Factorial validity was assessed with confirmatory factor analysis; construct validity was tested by correlating GAD-7 scores with PHQ-9 scores and other sociodemographic characteristics; internal consistency reliability was assessed using Cronbach's alpha and the composite reliability index, while confirmatory multigroup factor analysis was employed to investigate measurement invariance across gender and age (65 vs. 65). Results: We enrolled 398 patients (mean age 64.7 years; 78.9 % male; 66.8 % married). Factor structure was confirmed as unidimensional. Construct validity was confirmed with significant associations between GAD-7 and PHQ-9 scores, female gender, having a caregiver, and being employed. Cronbach's alpha and composite reliability index were 0.89 and 0.90, respectively. Measurement invariance across gender and age was confirmed at the scalar level. Limitations: A convenience sample in one European country, a small female sample, validity testing against a single criterion. Conclusion: Study results demonstrate adequate validity and reliability of the GAD-7 in an Italian CHD sample. It showed satisfactory invariance properties; GAD-7 is suitable for measuring anxiety in CHD while making significant comparisons of scores among stratified gender and age groups.