About 10% to 15% of women experience clinically significant depressive symptoms during pregnancy. Furthermore, women with a history of major depression appear to be at high risk for recurrent illness during pregnancy particularly in the setting of antidepressant discontinuation. We have long argued that it is important to identify and to offer treatment to women who suffer from depression during pregnancy, but we have yet to agree on what is the best instrument for this purpose.
One of the problems has been that tools commonly used to identify and measure depressive symptoms in the general population, such as the Hamilton Rating Scale for Depression (HAM-D) and the Beck Depression Inventory (BDI), include physical symptoms, such as appetite change and sleep disturbance. While these symptoms are typical depressive symptoms, they are also symptoms of a normal pregnancy.
The Edinburgh Postnatal Depression Scale (EPDS), although initially engineered to detect postpartum depression, has been used in pregnant populations; however, there has been considerable variability in the estimates of the sensitivity and specificity of the EPDS in this setting.
In a recent study Brazilian researchers compare the following instruments administered during pregnancy: MINI-PLUS, EPDS, BDI and HAM-D. A total of 247 consecutive women in their second trimester of pregnancy were recruited from the obstetrics clinic of a public hospital. Using the structured MINI-Plus interview to establish psychiatric diagnosis, the researchers observed that 17.34% of the patients were depressed, and 31.98% met the diagnostic criteria for lifetime major depression. The optimal cut-off points for this sample were chosen after applying Youden’s Index.
The ideal screening test must be both sensitive and specific. A test with high specificity is able to correctly identify patients who have the disease and will not miss too many cases. Specificity reflects the ability of the test to screen out those patients who do not have the disease. Many depression screening tools have low specificity because it is understood that those patients with positive scores will receive further evaluation to make a precise diagnosis.
EPDS > 11 81.58% sensitivity 73.33% specificity
BDI > 15 82.00% sensitivity 84.26% specificity
HAM-D > 9 87.76% sensitivity 74.60% specificity
The researchers concluded that that all of the scales examined can be considered as valid screening tools for antenatal depression. All three screening tools had narrow confidence intervals and yielded positive predictive values greater than 0.75. Moreover, all scales had good internal consistency (Cronbach’s ?=0.81). However, the BDI has better psychometric properties (with the highest AUC value of 0.90) than the more widely used EPDS.
The authors note several limitations. First, the women were assessed only during the second trimester, and the instruments may work differently in women at other time points during their pregnancy. They also note that the results may be applicable only to the Brazilian population since psychometric properties may vary in other populations.
Ruta Nonacs, MD PhD
Couto T, et al. What is the best tool for screening antenatal depression? J Affect Disord. 2015 Feb 26. [Epub ahead of print]
Kozinszky Z, Dudas RB. Validation studies of the Edinburgh Postnatal Depression Scale for the antenatal period. J Affect Disord. 2015 Jan 24; 176C:95-105.