**2.2 Treatment for depression**

Literature indicates that treatment for antenatal depression exists [53, 54]. A systematic review found that drug therapy, acupuncture, the use of morning light, individual psychotherapy, cognitive behavioural therapy, counselling and end psychodynamic therapy are forms of depression treatment that are used during pregnancy [55]. In addition, systematic reviews and controlled clinical trials found that various forms of psychotherapy [45, 54, 56–62], massage therapy [54, 61], exercise [63, 64], and drug therapy [55] may be effective in treating depression during pregnancy. This is supported by Whooley [65] who asserted that exercise and other self-management strategies, behavioural activation, structured psychotherapy, and/ or pharmacotherapy are effective treatments for depression.

However, some authors of systematic reviews have argued that there is no conclusive evidence on the effectiveness of these treatments for depression during pregnancy [54–56]. All in all one can argue that the lack of evidence on effectiveness of some treatments for depression during pregnancy does not mean that antenatal depression cannot be treated but simply means that evidence is not available.

#### **2.3 Instruments for screening of depression**

Screening for depression during pregnancy can be done using various instruments such as EPDS [66], Hopkins Symptoms Checklist 15 (HSCL-15) [67], SRQ [68] and Whooley's Questions [69]. Most of these screening instruments were not specifically developed for use during antenatal periods [66–68]. However, there are also numerous instruments for screening antenatal depression that were also validated for use in low resource settings [70] (**Table 1**).

Screening instruments which were validated in specific settings have a high likelihood of generating accurate results [71] and may reduce the under-detection of depression in those settings. However, screening instruments are generally limited in their accuracy [72] and their performance varies with populations or settings [73]. For instance, previous studies found that EPDS had different levels of accuracy and validity in antenatal clinics in various countries [10, 70, 74–76].

#### **2.4 Validity of screening instruments**


The performance of screening instruments may vary with settings [73]. A concern is that most instruments for the screening of depression were validated in high

#### **Table 1**

*Summary of screening instruments that were validated in low resource settings.*

#### *Screening for Antenatal Depression by Midwives in Low Resource Settings in Primary Care… DOI: http://dx.doi.org/10.5772/intechopen.97411*

income countries (HICs) whose contexts are dissimilar from those of low resource settings [77]. For example, there is evidence that the Edinburgh Postnatal Depression Scale's (EPDS) discriminant ability in detecting antenatal depression varies according to settings [74–76]. The two most commonly used instruments in low resource settings, namely the EPDS and the Self Reporting Questionnaire (SRQ), were reported to be easy to administer to pregnant women by interviewers in Malawi [10]. However, evidence is emerging that some health professionals may find screening instruments which have 5 or more items as long, cumbersome and time consuming for routine screening [47]. Ultra-brief screening instruments (having 4 or less items) can promote screening for depression in busy antenatal clinics [78] and screening instruments with binary questions such as Whooley's questions are less time consuming and easy to score [49].

It is documented that screening instruments which require individuals to choose more than 2 responses for each question may not be easy to apply among illiterate pregnant women in Malawi [10]. These screening instruments should be valid to assist health professionals to effectively detect antenatal depression [38, 79]. A validation process through the application of a gold standard (a clinical diagnostic assessment) is required to confirm a diagnosis of depression among pregnant women who test positive on a screening instrument.

Midwives should use valid screening instruments for them to effectively detect pregnant women with antenatal depression. A valid instrument should have an ability to measure what it is supposed to measure [80] and this is determined by its Se, Sp, PPV and NPV [81]. The sensitivity of a screening instrument refers to the proportion of people with disease that are correctly identified (true positives) by the instrument while specificity is the proportion of people without the disease who will have a negative result (true negatives) [71]. Sensitivity and specificity of a screening instrument are determined by comparing the results of the instrument against the outcomes of a gold standard. A gold standard is the single instrument (or a combination of instruments) that is considered the current preferred method of diagnosing a particular condition [82]. A good screening instrument should have both high sensitivity and specificity [83]. Nevertheless, sensitivity and specificity of a screening instrument are often in balance (trade off) and can vary with optimum cut off scores which are determined through using a Youden index [84, 85].

Both sensitivity and specificity are equally important although a screening instrument can be very specific without being sensitive, or it can be very sensitive without being specific [83]. It is recommended that a suitable screening instrument should have a minimum acceptable balance of Se/Sp (.8/.7) [86]. However, the sensitivity and specificity of a screening instrument has limited use in clinical practice when compared to PPV and NPV because they do not help clinicians to estimate the probability of disease in individual patients [71]. PPV and NPV measure the likelihood that a positive or negative screening result is accurate for an individual [53]. PPV and NPV of a screening instrument depend on the prevalence of disease in a population so that PPV increases with increasing prevalence of disease and NPV decreases with increasing prevalence [82].

These predictive values are more useful measures of diagnostic accuracy in routine clinical practice because they assist a clinician to know the probability of a correct diagnosis being made [71]. An instrument which has high sensitivity and NPV 'rules OUT' the disease while the one with high specificity and PPV 'rules IN' the disease [82]. Thus a highly sensitive screening instrument is most helpful to the clinician when the result is negative because an individual who screens negative is very unlikely to have the disease [71]. Similarly, a screening instrument with high specificity is also most helpful to the clinician when the result is positive because an individual who screens positive is likely to have the disease. Literature indicates that a screening instrument cannot be valid without it reliably and consistently measuring what it is supposed to measure [87]. This suggests that for effective screening of depression in antenatal clinics, clinicians must utilise accurate screening instruments. Screening for antenatal depression using valid instruments can assist health professionals to accurately identify pregnant women who need mental health interventions [79].

Accuracy refers to the degree to which a measurement represents the true value of the attribute being measured, and can be determined by comparing results from a screening instrument with results generated by a gold standard using scores for area under curve (AUC) [88], sensitivity and specificity [89]. In this context validity and accuracy may be used synonymously. AUC scores are used to categorise the accuracy of a screening instrument as low (0.5–0.7), moderate (>0.7–0.9) and high (>0.9) [90]. The higher the AUC score, the more accurate a screening instrument is in detecting individuals with or without the condition being tested [83]. As such, highly accurate instruments are necessary for the screening of depression in antenatal clinics [70]. In addition, these screening instruments should be quick and easy to use in low resource settings [8, 78].
