Abstract
BackgroundGeneralised anxiety disorder (GAD) frequently occurs amongst patients with tuberculosis (TB) and contributes to poor quality of life and treatment outcomes. This study evaluated the construct validity and reliability of the GAD-7 scale in a sample of patients with TB in the Free State Province.MethodsA pilot study was conducted amongst a convenience sample of 208 adult patients newly diagnosed with drug-susceptible TB attending primary healthcare (PHC) facilities in the Lejweleputswa District in the Free State. A structured interviewer-administered questionnaire comprising social demographic questions and the GAD-7 scale was used. Confirmatory factor analysis was used to investigate the construct validity of the GAD-7 scale. The reliability of the scale was assessed by calculating Cronbach’s alpha.ResultsThe analysis showed that a modified two-factor (somatic symptoms and cognitive -emotional symptoms) model, in which the items ‘Not being able to stop or control worrying’ and ‘Worrying too much about different things’ were allowed to covary (Comparative Fit Index: 0.996, Tucker–Lewis Index: 0.993, Root Mean Square Error of Approximation: 0.070, 90% confidence interval: 0.032–0.089), fitted the data better than a unidimensional (generalised anxiety) or an unmodified two-factor model. The indicators all showed significant positive factor loadings, with standardised coefficients ranging from 0.719 to 0.873. The Cronbach’s alpha of the scale was 0.86.ConclusionThe modified two-factor structure and high internal consistency respectively provide evidence for construct validity and reliability of the GAD-7 scale for assessing GAD amongst patients with TB. Studies are necessary to assess the performance of this brief scale under routine TB programme conditions in the Free State.
Highlights
Generalised anxiety disorder (GAD) frequently occurs amongst patients with tuberculosis (TB) and contributes to poor quality of life and treatment outcomes
The results indicate that a modified two-factor model, with somatic symptoms and cognitive-emotional symptoms as latent factors, that allows the items ‘Not being able to stop or control worrying’ and ‘Worrying too much about different things’ to covary, resulted in the best fit for the data when compared with a single-factor model with only generalised anxiety as an underlying factor, and an unmodified two-factor model
The results provide evidence for the construct validity of the GAD-7 scale in the sample studied
Summary
Generalised anxiety disorder (GAD) frequently occurs amongst patients with tuberculosis (TB) and contributes to poor quality of life and treatment outcomes. This study evaluated the construct validity and reliability of the GAD-7 scale in a sample of patients with TB in the Free State Province. Mental health is increasingly being prioritised globally as well as in South Africa. Generalised anxiety disorder (GAD) is a type of anxiety disorder characterised by overwhelming anxiety and worry about ordinary situations occuring frequently for at least 6 months.[1,3] If left untreated, GAD can impair patients’ quality of life and disease treatment outcomes.[4,5,6] Despite being treatable,[7] there are concerns that GAD remains largely underdiagnosed and undertreated in primary healthcare (PHC) settings in South Africa.[8]
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