1. The relevant construct I am nominating is postnatal depression.
2. The context for the construct to be measured is in English speaking European mothers of newborns in hospital or a clinical setting.
3. The available psychometric instruments proposed to measure postnatal depression in mothers are the Edinburgh Postnatal Depression Scale (EPDS), the Bromley Postnatal Depression Scale (BPDS), the Postpartum Depression Screening Scale (PDSS), the Leverton Questionnaire (LQ) and the Hung Postpartum Stress Scale (HPSS) (Zubaran, Schumacher, Roxo & Foresti, 2010, Wodonga Regional Health Services [WRHS], 2008).
In addition to this other scales have been used to measure this construct including the Short form of the Centre for Epidemiological Studies-Depression Scale (CES-Depression), Beck’s Depression Inventory (BDI), the Hamilton Depression Rating Scale (HDRS), the General Health Questionnaire (GHQ), the Zung Self-rating Depression Scale (Zung SDS) and the Inventory of Depressive Symptomatology (IDS) (Zubaran et al., 2010). These scales however have not been included in this report due to their construct validity not relating specifically to postnatal depression. In addition to this, item validity for depression scales are not accurate because postnatal depression often results in different symptoms compared with major depressive disorder hence, this needs to be reflected in the questions in the scale (Beck & Gable, 2001).
To find the available instruments, databases such as PsycInfo, EbscoHost, Google Scholar and Buros were used with specific search terms relating to the construct and context.
The EPDS was initially developed to help primary care health professionals to identify mothers experiencing postnatal depression in the United Kingdom (Cox, Holden & Sagovsky, 1987). It involves 10 short statements in which the mother underlines one of the four possible responses which match most appropriately to how she has been feeling over the past week. In addition to this a careful clinical assessment should also be carried out to confirm the diagnosis (Cox, et al., 1987). The EPDS is free and easily accessible which is beneficial for users (White, 2008). Furthermore, it requires little training and can be administered by a public health nurse successfully (Stewart et al., 2003). Mothers can usually complete the scale in less than five minutes (Cox et al., 1987).
The EPDS is criterion referenced and hence, does not base its responses or compare them to normative data (Cox et al., 1987). It has accurate item and construct validity; the items in the scale relate to maternal feelings over the last seven days and relate specifically to postnatal depression (Cox et al., 1987). An advantage of the EPDS over other scales is that it does not include common somatic symptoms such as appetite changes and insomnia which can occur naturally in new mothers (Stewart et al., 2003). In regards to the scales test/retest reliability, it is considered useful to repeat the test scale two weeks later to ensure similar results and this is recommended to increase reliability (Cox et al., 1987). Validity across cultures has been validated with the scale being translated for diverse cultures however; more recent research has found diversity and inconsistency in assessment procedures which indicates that cultural factors merit more attention. Cut-off scores are recommended based on Caucasian or homogenous samples and are not necessarily representative of other cultures (Stewart et al., 2003). Concurrent validity is evident as the EPDS is highly correlated with other measures of depression such as the BDI and the PPDS (Stewart et al., 2003). The internal consistency of the EPDS is rated good to excellent; Cronbach’s alpha resulted in a reliability coefficient of 0.87 (White, 2008). Inter-rater reliability is also considered to be good (White, 2008).
The EPDS is very simple and quick to use (Cox et al., 1987)....