The Gini Coefficient: A New Approach to Assess Physical Activity Inequality in COPD.

Increasing physical activity (PA) is a complex and challenging task in patients with chronic obstructive pulmonary disease (COPD). However, some questions are raised regarding the evaluation of PA in these patients: Have all aspects of PA evaluation in patients with COPD already been explored in the scientific literature and clinical practice? What is the clinical importance of assessing PA inequality? PA inequality is defined as the Gini coefficient (Gini) of the PA distribution of a population and is already shown to have implications for public health in the general population. It is a simple tool that might allow a better understanding of PA disparities among different COPD populations, although to our knowledge there is no previous investigation of PA inequality in patients with COPD using the Gini. In this perspective study we have provided examples of the Gini use in different scenarios. Future studies might try to apply it in order to identify subpopulations with higher PA inequality, and perhaps are therefore more prone to benefit most from interventions specifically tailored to promote PA. In summary, we propose the quantification of PA inequality with the Gini as a tool that might allow us to see PA even more comprehensively than we already do, expanding our perspective on PA in patients with COPD.