Clusters of maternal depressive symptoms in South Western Sydney, Australia

The purpose of this study is to explore the spatial distribution of perinatal depressive symptoms in South Western Sydney, Australia, and to identify any clusters that could inform subsequent qualitative, ecological and multilevel studies and local public health interventions. A routine survey of mothers with newborn infants was commenced in 2000. The survey included the Edinburgh Postnatal Depression Scale (EPDS). Mothers (n=15,389) delivering in 2002 and 2003 were assessed at 2-3 weeks after delivery for risk factors for depressive symptoms. The binary outcome variables were EPDS>9 and EPDS>12. EPDS>9 and EPDS>12 was mapped for 101 suburbs using likelihood standardised morbidity ratios (SMRs) and Bayesian log-normal models with conditional autoregressive (CAR) components. Open domain software SaTScan™ was used to test for the presence of clusters. The Bayesian methods identified clusters of depressive symptoms in north-east, north-west and southern areas of the study region. The northern clusters were statistically significant using SaTScan™. There were two high risk clusters of EPDS>9 (radius 4.3 and 5.6 km, both p<0.001) and two high risk clusters of EPDS>12 (radius 1.8 km p=0.003 and radius 3.97 km p=0.012). The clusters were in regions known to be socially disadvantaged and with high rates of non-English speaking migrants. The study findings will be used to inform future qualitative and epidemiological research, and to plan interagency early intervention services for women, children and their families.