Psychometric Properties of the GAD-Q-IV in Postpartum Mothers
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Generalized Anxiety Disorder (GAD) is a mental disorder with a main feature of excessive, impairing worry (American Psychiatric Association [APA], 2013). GAD symptoms are common for women during the postpartum period (Phillips, Sharpe, Matthey, & Charles, 2009). Postpartum mothers with GAD experience an array of negative outcomes including body image self-consciousness, elevated distress, and reduced emotional well-being (Wenzel, 2011). Although postpartum onset GAD is chronic (Prenoveau et al., 2013) and detrimental to the psychological well-being of mothers and their families (Wenzel, 2011), effective treatments for GAD exist, but postpartum mothers must first be screened and diagnosed to receive treatment. Currently a screening instrument for postpartum GAD does not exist. The purpose of this investigation is to gather psychometric information for the Generalized Anxiety Disorder Questionnaire-IV (GAD-Q-IV; Newman et al., 2002) with a sample of postpartum mothers.
Data were collected from 296 mothers recruited from post-delivery wards at the John Radcliffe Hospital in Oxford, England. Participation eligibility included mothers who were 18 years or older, spoke sufficient English, lived within 35 miles of Oxford, had no life-threatening medical conditions, planned to be the infant’s principal caretaker, and had delivery of an infant over 35 weeks gestation, over 4.41 pounds (2000 grams) birth weight, and no life-threatening medical complications.
The Generalized Anxiety Disorder Questionnaire (GAD-Q-IV). The GAD-Q-IV (Newman et al., 2002) revised version for the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition – Text Revision’s (DSM-IV-TR; APA, 2000) criteria was used to assess GAD symptoms. It is notable to mention that GAD criteria between the DSM-IV-TR and the DSM-5 remain virtually identical. The GAD-Q-IV is a nine-item self-report questionnaire including five yes or no response items (e.g., Do you experience excessive worry?), one open-ended item (e.g., Please list the most frequent topics about which you worry excessively or uncontrollably), one multiple-selection item with all six DSM symptoms for GAD, and two Likert-type items (e.g., How much are you bothered by worry and physical symptoms?) with responses ranging from zero (no distress) to eight (very severe distress). Data collected from college students with the GAD-Q-IV have provided evidence of internal consistency (Cronbach’s α = .83; Rodebaugh, Holaway, & Heimberg, 2008), test-retest reliability, convergent validity with the Penn State Worry Questionnaire (PSWQ; Meyer, Miller, Metzger, & Borkovec, 1990).
The Structured Clinical Interview for DSM-IV-TR (SCID-I-RV). The SCID-I-RV (research version; First & Gibbon, 2004) is a structured interview used for diagnosing psychiatric disorders based on DSM-IV-TR criteria. The SCID-I-RV was used in the present study to assess the presence or absence of GAD. Diagnoses from the SCID-I-RV have demonstrated good inter-rater reliability for GAD (Kappa = .75; Lobbestael, Leurgans, & Arntz, 2011).
The GAD-Q-IV was used to screen our sample of postpartum mothers for GAD symptoms nine weeks postpartum (9WP) at the participants’ homes. Second home visits were conducted six months postpartum (6MP) to reassess mothers’ diagnoses using the SCID-I-RV. At the 6MP assessment, mothers were re-interviewed using the SCID-I-RV and the GAD-Q-IV.
Planned Data Analysis
Data will be analyzed with SPSS (version 22.0) and Mplus (version 7). Descriptive statistics (e.g., percentages) will be calculated for demographic variables and SCID-I-RV diagnoses of GAD. Means, standard deviations, actual ranges, and Cronbach’s alphas will be calculated for the GAD-Q-IV responses. The factor structure of the GAD-Q-IV with postpartum mothers is unknown. Therefore, exploratory factor analysis (EFA) will be used to explore the factor structure and confirmatory factor analysis (CFA) will be used to confirm this structure of the data provided by the postpartum mothers. EFA will be conducted to examine the factor structure of the GAD-Q-IV responses with the 9WP data. Then, the factor structure found from EFA will be cross-validated with the GAD-Q-IV responses from 6MP data using CFA.
The 6MP data will be analyzed for the sensitivity (percent of true positives) and specificity (percent of true negatives) of the GAD-Q-IV responses with receiver-operating characteristic (ROC) analyses. The ROC will be used to set a cut-off score with the highest percentages of sensitivity and specificity by comparing the continuous GAD-Q-IV scores to SCID-I-RV diagnoses. A cut-off score with the highest possible sensitivity and specificity percentages will be set with ROC. This GAD-Q-IV cut-off score can be used to categorize postpartum mothers as either positive (above the cut-off) or negative (below the cut-off). This cut-off score can serve as a recommendation to detect the likely presence or absence of GAD in postpartum mothers. If a cut-off score has sensitivity and specificity comparable to previous findings (Newman et al., 2002), this will provide evidence for the utilization of the GAD-Q-IV as a diagnostic screening instrument of GAD for postpartum mothers.
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