Use of the Lorenz curve and the Gini index for the evaluation of HIV viral load distribution in an Italian community

Background: Community viral load (CVL) is defined as an aggregate measure of individual viral loads of people living with HIV who are receiving care in a specific community. It serves as a metric to evaluate the effectiveness of therapy programs. Our study aimed to analyze the overtime trend and the distribution characteristics of viral load. Methods: Using the Lorenz curve, we investigated the demographic characteristics of individuals who comprised the top 10% of viral loads over the years. We applied the Gini index to measure the inequality in the distribution of viral load among the study population. Results: Our data showed a progressive decrease in community viral load over the years, with a sharp decline after 2012 and a rebound in 2020. The Gini index had a specular trend during this period. In all the observed periods, the top 10% of viral loads showed a progressive increase in the proportion of female individuals and non-Italian nationals. Conclusion: Our study highlighted the effectiveness and the improvement of the HIV care cascade over the years, with a decrease in community HIV viral load. The introduction of integrase inhibitors seemed to cause a rapid drop in community viral load in 2012 but with a notable discrepancy in the homogeneity of the population. It is also important to highlight the changes over time in the population representing the top 10% of viral loads, with a gradual but stable increase in the proportion of female and non-Italian individuals.