Significant geographic inequalities have been reported in the distribution of both severe mental illness (SMI) and type 2 diabetes (T2D). However, the geographic variations in their comorbidity have not been previously explored. Exploring neighbourhood inequalities in the co-occurrence of SMI-T2D may improve our understanding of the overlapping prevalence of these two chronic diseases and may also assist public health authorities to cost-effectively target local resources and preventive interventions to reduce the regional disparities and public health burden imposed by the comorbidity.
This study aimed to provide an insight into the geography of serious mental illness – type 2 diabetes comorbidity in the Illawarra-Shoalhaven region of NSW, Australia and to identify the significant clusters and their locations.
In this cross-sectional study, spatial analytical methods were applied to routinely collected clinical data. The geographic variation in comorbidity was measured by Global Moran’s I. Local Indicators of Spatial Association (LISA) and Spatial scan statistic were used in order to identify local spatial clusters.
The study identified significant geographic variations in the distribution of SMI –T2D comorbidity in Illawarra Shoalhaven. Consistently higher burden of comorbidity was observed in some urban suburbs surrounding the major metropolitan city.
Our results revealed evidence of spatial variations in the distribution of SMI -T2D comorbidity. Further investigation is however required to determine whether contextual environmental factors, such as neighbourhood socioeconomic disadvantage, may be explanatory.