Spatial and temporal trend analysis of the prevalence of multimorbidity and its association with socioeconomic disadvantage in South Africa

South Africa is facing a new public health challenge with chronic infectious and non-communicable diseases, and multimorbidity becoming increasingly prevalent in an ageing population. The aim of the study was to investigate... [ view full abstract ]

South Africa is facing a new public health challenge with chronic infectious and non-communicable diseases, and multimorbidity becoming increasingly prevalent in an ageing population. The aim of the study was to investigate the spatiotemporal epidemiology of prevalent chronic diseases (diabetes, hypertension, tuberculosis (TB) and HIV), multimorbidity and the association with socioeconomic disadvantage in South Africa.

This study utilised 2008 and 2012 data from the National Income Dynamics Study, a longitudinal study with a sample of approximately 28 000 respondents. Cross-sectional analyses and logistic regression modelling were used to investigate associations between chronic disease multimorbidity, socioeconomic status and selected risk factors. Spatial hot spot analysis using the Getis-Ord Gi* statistic highlighted the spatial distribution of multimorbidity across the 2011 Census districts of South Africa.

Multimorbidity increased in prevalence from 2.73% to 2.84% in South African adults between 2008 and 2012 (average age of 53.7 years in 2008 and 55.1 years in 2012). Multimorbidity was associated with socioeconomic deprivation, obesity, and age, and was higher in urban areas. The most common combinations of co-morbidities were hypertension/diabetes, TB/hypertension and HIV/hypertension. Self-reported TB and HIV prevalence were significantly under-reported compared to available national data. Spatial analysis showed hot spots of higher multimorbidity prevalence in parts of the KwaZulu-Natal and Eastern Cape provinces, and this pattern mirrored the spatial pattern of socioeconomic disadvantage.

This study contributes towards data on multimorbidity in low and middle-income countries and the important role of hypertension in multimorbidity. It provides a foundation for future research on the components of socioeconomic disadvantage that drive chronic disease multimorbidity. The study also highlights the limitation of survey data on self-reported TB and HIV status; disease associated with stigma. This interdisciplinary study will therefore be of significant interest to researchers and policy makers concerned with population health and the effect of place and context.