Validation of screening tools for antenatal depression in Malawi—A comparison of the Edinburgh Postnatal Depression Scale and Self Reporting Questionnaire

Abstract

Background

The detection of antenatal depression in resource-limited settings such as Malawi, Africa, is important and requires an accurate and practical screening tool. It is not known which questionnaire would be most suitable for this purpose.

Method

A rigorously translated and modified Chichewa version of the Edinburgh Postnatal Depression Scale (EPDS) was developed. The Chichewa EPDS and an existing Chichewa version of the Self Reporting Questionnaire (SRQ) were validated in women attending an antenatal clinic in rural Malawi, using DSM-IV major and major-or-minor depressive episode as the gold standard diagnoses, determined with Structured Clinical Interview for DSM-IV (SCID). Weighted test characteristics for each possible cut-off were calculated and Receiver Operator Characteristic (ROC) curves derived.

Results

The participants were 224 pregnant women, 92 of whom were interviewed using the SCID. The area under the ROC curve (AUC) for detection of current major depressive disorder for the EPDS was 0.811 (95% CI 0.734-0.889) and for the SRQ was 0.833 (95% CI 0.770-0.897). AUC for major-or-minor depressive disorder for the EPDS was 0.767 (95% CI 0.695-0.839) and for the SRQ was 0.883 (95% CI 0.839-0.927). These were not significant differences. Internal consistency was high for both the SRQ (Cronbach's alpha 0.825) and the EPDS (Cronbach's alpha 0.904).

Limitations

Inter-rater reliability testing was not done. The relatively small sample size resulted in wide confidence intervals around AUCs. The study was conducted amongst antenatal clinic attenders only, limiting generalisability to all pregnant women in this setting.

Conclusion

The Chichewa versions of the EPDS and SRQ both show utility as brief screening measures for detection of antenatal depression in rural Malawi.

Introduction

Maternal depression, anxiety and psychological distress during pregnancy and the puerperal period are common in low and middle income countries (LMIC) (Fisher et al., 2012). Mean weighted prevalence estimates of antenatal and postnatal depression in sub-Saharan Africa are 11.3% and 18.3% respectively; perinatal anxiety is also common (Sawyer et al., 2010). Until recently, attention has focused on postnatal depression but the importance of depression antenatally is increasingly recognised. Antenatal depression is a risk factor for postnatal depression (Robertson et al., 2004). In studies from LMIC, antenatal depression/distress has been associated with maternal disability (Bindt et al., 2012) and, in longitudinal studies, has been shown to be a risk factor for low birth weight (Patel et al., 2002), prolonged labour (Hanlon et al., 2009), delay in initiating breastfeeding (Hanlon et al., 2009), and early cessation of exclusive breastfeeding (Patel and Prince, 2006). Depression persisting from pregnancy into the postnatal period has been associated with increased risk of infant diarrhoea in Ethiopia (Ross et al., 2011) and greater infant growth impairment in Pakistan (Rahman et al., 2004).

The World Health Organisation's Mental Health Gap Action Project (mhGAP) calls for mental health to be integrated into primary health care in LMIC (WHO, 2008). The detection of depression in primary care by non-specialist health workers may be aided by the use of brief and valid depression screening measures. Such measures need to have been validated after careful consideration of the impact that culture and language may have upon the validity of the measure. This requires a careful process of translation, back-translation and modification to ensure cross-cultural equivalence (Rahman et al., 2003). Screening measures validated for use in the postnatal period in sub-Saharan Africa include the Self Reporting Questionnaire (SRQ) (Hanlon et al., 2008, Weobong et al., 2009, Stewart et al., 2009), Edinburgh Postnatal Depression Scale (EPDS) (Chibanda et al., 2010, Uwakwe and Okonkwo, 2003, Tesfaye et al., 2010, Bass et al., 2008, Weobong et al., 2009), Zung Self Rating Depression Scale (Uwakwe and Okonkwo, 2003), Kessler Scales (K10 and K6) (Tesfaye et al., 2010, Baggaley et al., 2007), and the Patient Health Questionnaire (PHQ-9) (Tesfaye et al., 2010, Weobong et al., 2009). Scales validated in the antenatal period are the SRQ (Hanlon et al., 2008), EPDS (Adewuya et al., 2006) and Hopkins Symptom Checklist 25 (HSCL-25) (Kaaya et al., 2002).

Prior to this study, no depression screening tools had been validated for use in an antenatal population in Malawi. The purpose of this study was to compare the performance of the SRQ and EPDS. Both instruments have been validated in other sub-Saharan African countries, but have key differences that may affect their usefulness in rural Malawi.

The SRQ was designed by the World Health Organisation as a screen for common mental disorders (WHO, 1994). It includes items enquiring about depression, anxiety and non-specific somatic complaints. The SRQ has been used in a number of studies of antenatal psychological wellbeing in South Asia and Africa (Husain et al., 2011, Medhin et al., 2010, Rahman and Creed, 2007, Ola et al., 2011). To date, there has been only one validation of the SRQ in an antenatal population in sub-Saharan Africa (Hanlon et al., 2008). In a previous study of mothers attending a paediatric clinic in rural Malawi, we showed that the SRQ, modified and translated into Chichewa (the most commonly spoken language in Malawi), was useful as a brief screening measure for depressive disorder (Stewart et al., 2009).

Unlike the SRQ, the EPDS was specifically designed for the postnatal period and excludes somatic items that might cause difficulty since somatic symptoms occur as part of the normal puerperium (Cox et al., 1987). It has been successfully validated in pregnancy when physical symptoms are also common (Gibson et al., 2009). However, it has been suggested that, particularly in LMIC, somatic symptoms are important presenting symptoms of psychological distress/depression and should not be excluded from screening measures (WHO, 1994). Also, the EPDS might be less applicable than the SRQ in predominantly illiterate populations as it requires respondents to choose between 4 options for each question rather than two (yes/no). There have been conflicting reports of the validity of the EPDS amongst women in the postnatal period in Ethiopia and Ghana; Hanlon et al (2008) found that the EPDS had poor test characteristics in rural Ethiopia, but it performed adequately in an urban setting in Ethiopia (Tesfaye et al., 2010) and a rural setting in Ghana (Weobong et al., 2009). As of March 2013, there has been no published validation of the EPDS in a low-literacy predominantly rural antenatal population in sub-Saharan Africa. Previous studies have been in postnatal groups (Hanlon et al., 2008, Tesfaye et al., 2010, Weobong et al., 2009) or in a high literacy urban antenatal population (Adewuya et al., 2006).

The first aim of this study was to translate and adapt the EPDS into Chichewa. The second was to validate the Chichewa versions of EPDS and SRQ in a predominantly rural population of pregnant women using DSM-IV major and major-or-minor depression as the gold-standard criteria. The third aim was to compare the ease of administration and test characteristics of the EPDS and SRQ.