Mind the gap : revisiting the concentration index for overweight

Much analysis of the socioeconomic gradient of overweight/obesity has involved the calculation of concentration indices for the incidence of these conditions. However this analysis ignores the severity of the conditions, in particular whether there is a gradient to how far are people above the relevant thresholds. Calculation of the concentration index for severity based measures for a dataset for Ireland reveals a much stronger gradient than for the incidence based measures. It is recommended that analysis of severity should always accompany analysis of the incidence of overweight/obesity.