Factor structure of the Edinburgh Postnatal Depression Scale in a population-based sample.

Abstract

This is the accepted version of the paper.This version of the publication may differ from the final published version. Copyright and reuse: City Research Online aims to make research outputs of City, University of London available to a wider audience. Copyright and Moral Rights remain with the author(s) and/or copyright holders. URLs from City Research Online may be freely distributed and linked to. City Research Online: http://openaccess.city.ac.uk/ publications@city.ac.uk Permanent repository link: City Research OnlineRunning head: FACTOR STRUCTURE OF THE EPDS Factor structure of the Edinburgh Postnatal Depression Scale in a population-based sample FACTOR STRUCTURE OF THE EPDS 2 AbstractTo demonstrate validity, questionnaires should measure the same construct in different groups and across time. The Edinburgh Postnatal Depression Scale (EPDS) was designed as a unidimensional scale, but factor analyses of the EPDS have been equivocal, and demonstrate other structures: this may be due to sample characteristics and timing of administration. We aimed to examine the factor structure of the EPDS in pregnancy and postpartum at four time-points in a large population-based sample. We carried out exploratory and confirmatory factor analysis on the Avon Longitudinal Study of Parents and Children sample (n = 11,195 -12,166) randomly split in two. We used data from 18and 32 weeks pregnancy gestation; and 8 weeks and 8 months postpartum. A three-factor solution was optimal at all time-points, showing the clearest factor structure and best model fit: Depression (four items) accounted for 43.5 -47.2% of the variance; anhedonia (two items) 10.5 -11.1%; and anxiety (three items) 8.3 -9.4% of the variance. Internal reliability of subscales was good at all time points (Cronbach's alphas: .73 -.78). The EPDS appears to measure three related factors of depression, anhedonia and anxiety and has a stable structure in pregnancy and the first postnatal year.Keywords: ALSPAC, depression, anxiety, postnatal, pregnancy, factor analysis FACTOR STRUCTURE OF THE EPDS 3Factor structure of the Edinburgh Postnatal Depression Scale in a population-based sampleIn pregnancy and the first postnatal year 10-20% of women experience mental illness (Bauer et al., 2014) with detrimental effects on the whole family (Gavin et al., 2005). Interventions can ease symptoms and improve wellbeing of mothers (Dennis & Hodnett, 2007), however effective treatment is hampered by low levels of identification of perinatal mental illness with 50% of women with depression and anxiety not identified (Hewitt et al., 2009) evidence that the EPDS also measures anxiety with three items and that the summed score of these items can differentiate between anxiety and depressive disorders (Bowen, Bowen, Maslany, & Muhajarina, 2008;Matthey, Fisher, & Rowe, 2012; Ross, Evans, Seller, & Romach, 2003) although further research is needed to determine its acceptability, validity and reliability and psychometric properties as a measure of anxiety (Milgrom & Gemmill, 2014). A re...

Subconstructs of the Edinburgh Postnatal Depression Scale in a multi-ethnic inner-city population in the U.S.

“…Our findings are most consistent with the results in a study of Italian women (measured 2–3 days postpartum) identified by EFA with oblique rotation (Petrozzi and Gagliardi 2013) and a population-based study of women living in southwest England (measured at 18 and 32 weeks gestation, and 8 weeks and 8 months postpartum) identified by EFA with oblique rotation and CFA with maximum likelihood estimation (Coates et al 2016), both suggesting a three-factor structure including depression (items 7–10), anxiety (items 3–6), and anhedonia (items 1–2). Another study conducted via an internet survey measured at approximately 6.5 months postpartum also found a similar three-factor structure (items 7–10 for depression; items 3–5 for anxiety; items 1–2 for anhedonia) by EFA with direct quartimin rotation (Tuohy and McVey 2008).…”

“…Overall, a three-factor model consisting of item clusters corresponding to postpartum symptoms including depressed mood, anhedonia, and anxiety provided the best fit, similar to those reported in Tuohy & McVey (Tuohy and McVey 2008), Petrozzi & Gagliardi (Petrozzi and Gagliardi 2013), and Coates et al (Coates et al 2016). In our ethnically mixed sample, the groupings differed slightly for the Hispanic subgroup compared to the African American or non-Hispanic White subgroups by one item (overwhelmed) that clustered with anxiety-type items in the former rather than depression-type items in the African Americans and Whites.…”

“…These analyses suggest that item 6 (overwhelmed) may be related to different or even multiple subconstructs depending on different population characteristics. Compared to our sample (mean age 27.0 years, mean total EPDS score=5.24), the Italian sample (Petrozzi and Gagliardi 2013) was older (mean age 32.3 years) with a similar mean total EPDS score (mean=5.3), the U.K. sample (Coates et al 2016) was similar in age (approximately 28 years old) with similar total EPDS score (median=5), and women in the internet survey study (Tuohy and McVey 2008) were older (mean age 30.2 years) with a higher average total EPDS score (mean=9.5). A study of women in Brazil (mean age=25.3 years) that also reported a three-factor structure has identified item 6 as being most relevant to anhedonia (items 7–10 for depression; items 3–5 for anxiety; items 1,2,6 for anhedonia) by CFA and an Exploratory Structural Equation Model using geomin oblique rotation (Reichenheim et al 2011).…”

“…In addition to differences in sample characteristics that may influence the structure of the EPDS, it has been suggested that timing of administration may also play a role. A recent study by Coates et al (2016) examined the structure of the EPDS at different timepoints (prenatal, 8 weeks and 8 months postnatally) and found that a three-factor solution was most optimal at all timepoints including depression (items 7–10), anhedonia (items 1 and 2) and anxiety (items 3–6); these authors also found similar factor loadings across all timepoints. As Coates et al (2016) pointed out, studies finding the three-factor solution tend to have a larger sample size (n>400) suggesting that as correlation patterns become more stable with a larger sample, items separate into depression and anhedonia subconstructs, in addition to the anxiety subconstruct.…”

“…While some have argued for the continued use of the EPDS as a uni-dimensional scale (Reichenheim et al 2011), a growing number of studies demonstrate that a three-factor solution may be most optimal, including three related factors of depression, anhedonia, and anxiety similar to our population (Coates et al 2016; Cunningham et al 2015; Zhong et al 2014). In addition to differences in sample characteristics that may influence the structure of the EPDS, it has been suggested that timing of administration may also play a role.…”