The health effects of gender are mediated via group-level constraints of sex roles and norms, discrimination and marginalisation of individuals, and internalisation of the stresses of role discordance. Although gender is frequently a lens through which data are interpreted there are few composite measures that insert gender as an independent variable into research design. Instead, sex disaggregation of data is often conflated with gender, identifying statistically significant but sometimes clinically insignificant sex differences. To directly assess the impact of gender on wellbeing requires development of group and individual-level derived variables. At the ecological level such a summative variable could be composed of a selection of group-level measures of equality between sexes. This gender index could be used in ecological and individual-level studies of health outcomes. A quantitative indicator of gender role acceptance and of the personal effects of gender inequities could insert the often hidden variable of gender into individual-level clinical research.