Relationship between a diagnostic measure and a symptom inventory in identifying Major Depressive Episode (MDE) in low-income urban mothers

Background: Increased efforts to identify and treat depressed mothers have accompanied the recognition of maternal depression as a major public health issue. Maternal depressive illness can be evaluated based on symptom severity or diagnostic criteria. Little is known about the relationship between these two approaches among low-income urban mothers who experience high levels of situational stress and chronically high symptom burdens.

Methods: We analyzed cross-sectional data from 239 mothers recruited from child-centered community sites. Depressive symptoms were measured using a symptom inventory, the Quick Inventory of Depressive Symptoms (QIDS). The Mini International Neurodiagnostic Interview (MINI), which also provides a measure of functioning, served as a diagnostic measure. We calculated the sensitivity and specificity of the QIDS using the accepted cutpoint of 11, which is associated with moderate symptoms.

Results: The baseline prevalence of MDE was 13%. The sensitivity of the QIDS to identify MDE was 97%; the specificity was 79%. Of the 44 false positives, 15 (34%) were misclassified solely due to the absence of functional impairment as measured on the MINI.

Conclusion: In this population of mothers, the QIDS has excellent performance characteristics when judged against the MINI. However, some women endorse high levels of depressive symptoms in the absence of functional impairment. As practitioners, we cannot assume that a certain level of symptom burden is related to impairment in daily functioning. These data highlight the importance of using functional assessments to compliment symptom assessments in order to improve the identification of at-risk women.