The study authors noted that most cases of postpartum depression are not diagnosed. Although there are many reasons for the lack of universal screening for postpartum depression, the length of screening instruments and the difficulties in adding this to an already crowded periodic schedule of examination and screening during infant health maintenance visits are barriers to implementation. The study authors reviewed the fact that postpartum depression involves a significant component of anxiety, making postpartum depression somewhat different from other forms of depression.
This study evaluated subsets of questions from a validated 10-item screening tool, the Edinburgh Postpartum Depression Scale, in an effort to refine a depression screening tool that was specific for postpartum depression and even briefer than the 10-item scale. This study compared 7-item, 3-item, and 2-item subsets of the Edinburgh Postpartum Depression Scale questions in 199 mothers ages 14-26 years old. Mothers were enrolled when they presented to a single outpatient clinic along with their children 0-6 months old. The racial and ethnic backgrounds of the mothers were varied, with 35.7% black, 16.1%, white, 44.2% Hispanic, and 4% Pacific Islander/Native American. This was a high-risk maternal cohort, with 43% not completing or failing high school.
The mothers completed the 10-item Edinburgh Postpartum Depression Scale, and a score of at least 10 was considered "depressed." The study authors then compared how the 3 subsets of questions compared with the full scale, adjusting the shorter scales such that a "10" on their adjusted scales was still considered evidence of depression. The subjects usually completed the instrument at more than 1 visit, with the first completion occurring at 2.1 months on average.
In this study, 20.6% of the mothers required referral for additional care owing to a "positive" score on the 10-item scale. The 3-item scale focused on questions related to anxiety, and this scale performed well with 95% sensitivity and a negative predictive value (the chance that the subject is not depressed, given a negative screening test) of 98%. It identified more mothers as depressed, at 35% of this sample. The 2-item scale did not perform well, and the 7-item scale had relatively low sensitivity.
The study authors concluded that the 3-item scale, focusing on the anxiety questions, performed as well as the 10-item scale in identifying women at risk for postpartum depression. They suggested that use of this brief questionnaire can improve detection of postpartum depression. They also cautioned that the 3-item questionnaire was not compared with a psychiatric interview (the "gold standard" for diagnosing depression), so full implementation of the 3-item questionnaire should await that validation.