Does the ‘inverse equity hypothesis’ explain how both poverty and wealth can be associated with HIV prevalence in sub-Saharan Africa?

Hargreaves, J; Davey, C; White, R Journal of Epidemiology & Community Health, 2012;

Is it relative wealth or relative poverty that drives the HIV epidemic in sub-Saharan Africa? This is a controversial aspect of HIV/AIDS epidemiology. These researchers suggest that the social epidemiology of HIV in Africa is changing.

Previously, new infections were more rapidly acquired by those of relatively higher socioeconomic position (SEP). More recently, those of relatively low SEP are at greater risk. This paper suggests that this pattern would be compatible with Cesar Victora’s ‘inverse equity hypothesis’, first articulated in relation to child morbidity and mortality. The hypothesis suggests that those of higher SEP benefit first from new health interventions.

This study suggests five methodological reasons for the diversity in the association between SEP and HIV infection rates noted in African studies:

  1. a range of different populations have been studied
  2. study sampling frames vary
  3. various methods of SEP measurement have been used
  4. studies take different approaches to adjustment and stratification of analyses
  5. some studies have examined patterns of infections

Before 1996, studies were more likely to find higher SEP associated with higher HIV risk, while after 1996, studies have been increasingly finding the opposite association. This paper does not concentrate on the empirical evidence for this assertion but rather focuses on describing how health-equity theory from another area of public health might be relevant to the changing social epidemiology of HIV infection. It argues that Cesar Victora’s ‘inverse equity hypothesis’ provides a compelling explanation for the apparently contradictory patterns of association between SEP and HIV reported in the literature, and the pattern of change over time.

Available evidence suggests that in the early phase of the epidemic, HIV infections were concentrated among those of higher SEP in many countries. The ‘inverse equity hypothesis’ suggests that new infections will increasingly concentrate among those of lower SEP. If further analysis confirms this hypothesis, policy responses must be considered.


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