Identifying perinatal depression with case-finding instruments: a mixed-methods study (BaBY PaNDA – Born and Bred in Yorkshire PeriNatal Depression Diagnostic Accuracy)

Background: Perinatal depression is well recognised as a mental health condition but < 50% of cases are identified in routine practice. A case-finding strategy using the Whooley questions is currently recommended by the National Institute for Health and Care Excellence. Objectives: To determine the diagnostic accuracy, acceptability and cost-effectiveness of the Whooley questions and the Edinburgh Postnatal Depression Scale (EPDS) to identify perinatal depression. Design: A prospective diagnostic accuracy cohort study, with concurrent qualitative and economic evaluations. Setting: Maternity services in England. Participants: A total of 391 pregnant women. Main outcome measures: Women completed the Whooley questions, EPDS and a diagnostic reference standard (Clinical Interview Schedule – Revised) during pregnancy (20 weeks) and postnatally (3–4 months). Qualitative interviews were conducted with health professionals (HPs) and a subsample of women. Results: Diagnostic accuracy results: depression prevalence rates were 10.3% during pregnancy and 10.5% postnatally. The Whooley questions and EPDS (cut-off point of ≥ 10) performed reasonably well, with comparable sensitivity [pregnancy: Whooley questions 85.0%, 95% confidence interval (CI) 70.2% to 94.3%; EPDS 82.5%, 95% CI 67.2% to 92.7%; postnatally: Whooley questions 85.7%, 95% CI 69.7% to 95.2%; EPDS 82.9%, 95% CI 66.4% to 93.4%] and specificity (pregnancy: Whooley questions 83.7%, 95% CI 79.4% to 87.4%; EPDS 86.6%, 95% CI 82.5% to 90.0%; postnatally: Whooley questions 80.6%, 95% CI 75.7% to 84.9%; EPDS 87.6%, 95% CI 83.3% to 91.1%). Diagnostic accuracy of the EPDS (cut-off point of ≥ 13) was poor at both time points (pregnancy: sensitivity 45%, 95% CI 29.3% to 61.5%, and specificity 95.7%, 95% CI 93.0% to 97.6%; postnatally: sensitivity 62.9%, 95% CI 44.9% to 78.5%, and specificity 95.7%, 95% CI 92.7% to 97.7%). Qualitative evaluation: women and HPs were supportive of screening/case-finding for perinatal depression. The EPDS was preferred to the Whooley questions by women and HPs, mainly because of its ‘softer’ wording. Whooley question 1 was thought to be less acceptable, largely because of the terms ‘depressed’ and ‘hopeless’, leading to women not revealing their depressive symptoms. HPs identified a ‘patient-centred’ environment that focused on the mother and baby to promote discussion about mental health. Cost-effectiveness results: screening/case-finding using the Whooley questions or the EPDS alone was not the most cost-effective strategy. A two-stage strategy, ‘Whooley questions followed by the Patient Health Questionnaire’ (a measure assessing depression symptomatology), was the most cost-effective strategy in the range between £20,000 and £30,000 per quality-adjusted life-year in both the prenatal and postnatal decision models. Limitations: Perinatal depression diagnosis was not cross-referenced with women’s medical records so the proportion of new cases identified is unknown. The clinical effectiveness and cost-effectiveness of screening/case-finding strategies was not assessed as part of a randomised controlled trial. Conclusions: The Whooley questions and EPDS had acceptable sensitivity and specificity, but their use in practice might be limited by low predictive value and variation in their acceptability. A two-stage strategy was more cost-effective than single-stage strategies. Neither case-finding instrument met National Screening Committee criteria. Future work: The yield of screening/case-finding should be established with reference to health-care records. The clinical effectiveness and cost-effectiveness of screening/case-finding for perinatal depression needs to be tested in a randomised controlled trial. Funding: The National Institute for Health Research Health Services and Delivery Research programme