An urgent call for the environmental sustainability of health systems: A 'sextuple aim' to care for patients, costs, providers, population equity and the planet.

Health systems have a duty to protect the health and well-being of individuals and populations. Yet, healthcare contributes about 4.6% of global greenhouse gas emissions. Health systems need to question and improve established practices, assume strong environmental leadership, and aim for ambitious, sometimes radical, actions in favour of the climate. In this paper, we interrogate the suitability and feasibility of integrating the aim of 'environmental sustainability' to form the 'Sextuple Aim.' Environmental sustainability may be in tension with, but also a potential lever to meet the other cardinal aims: (1) quality and experience of patient care; (2) population health; (3) quality of work and satisfaction of healthcare providers; (4) equity and inclusion; and (5) cost reduction. We propose policy and practical avenues to help move towards the Sextuple Aim.