Melioidosis–a disease of socioeconomic disadvantage

Abstract

Background

There is growing recognition of the contribution of the social determinants of health to the burden of many infectious diseases. However, the relationship between socioeconomic status and the incidence and outcome of melioidosis is incompletely defined.

Methods

All residents of Far North Queensland, tropical Australia with culture-proven melioidosis between January 1998 and December 2020 were eligible for the study. Their demographics, comorbidities and socioeconomic status were correlated with their clinical course. Socioeconomic status was determined using the Socio-Economic Indexes for Areas (SEIFA) Index of Relative Socio-economic Disadvantage score, a measure of socioeconomic disadvantage developed by the Australian Bureau of Statistics. Socioeconomic disadvantage was defined as residence in a region with a SEIFA score in the lowest decile in Australia.

Results

321 eligible individuals were diagnosed with melioidosis during the study period, 174 (54.2%) identified as Indigenous Australians; 223/321 (69.5%) were bacteraemic, 85/321 (26.5%) required Intensive Care Unit (ICU) admission and 37/321 (11.5%) died. 156/321 (48.6%) were socioeconomically disadvantaged, compared with 56603/269002 (21.0%) of the local general population (p<0.001). Socioeconomically disadvantaged patients were younger, more likely to be female, Indigenous, diabetic or have renal disease. They were also more likely to die prior to hospital discharge (26/156 (16.7%) versus 11/165 (6.7%), p = 0.002) and to die at a younger age (median (IQR) age: 50 (38–68) versus 65 (59–81) years, p = 0.02). In multivariate analysis that included age, Indigenous status, the presence of bacteraemia, ICU admission and the year of hospitalisation, only socioeconomic disadvantage (odds ratio (OR) (95% confidence interval (CI)): 2.49 (1.16–5.35), p = 0.02) and ICU admission (OR (95% CI): 4.79 (2.33–9.86), p<0.001) were independently associated with death.

Conclusion

Melioidosis is disease of socioeconomic disadvantage. A more holistic approach to the delivery of healthcare which addresses the social determinants of health is necessary to reduce the burden of this life-threatening disease.

Author summary

The social determinants of health—the circumstances in which people grow, live, work, and age, and the systems put in place to deal with illness—have a profound effect on how, when, and even if patients access healthcare, and yet they are generally under-appreciated by practicing clinicians whose training emphasises the biomedical model of healthcare. In this region of tropical Australia patients diagnosed with melioidosis were more likely to live in a socioeconomically disadvantaged region. Socioeconomically disadvantaged individuals with melioidosis were also more likely to die from their infection and to die at a younger age. It was notable that socioeconomic disadvantage had a greater independent association with in-hospital death than age, Indigenous status, the presence of bacteraemia or any of the comorbidities that classically predispose individuals to melioidosis. A more holistic approach to the delivery of healthcare—which addresses the social determinants of health—is necessary if we are to reduce the burden of melioidosis and the many other health conditions that disproportionately affect the most disadvantaged members of our society.