Health policy and systems research: the future of the field.

Health policy and systems research (HPSR) has changed considerably over the last 20 years, but its main purpose remains to inform and influence health policies and systems. Whereas goals that underpin health systems have endured - such as a focus on health equity - contexts and priorities change, research methods progress, and health organisations continue to learn and adapt, in part by using HPSR. For HPSR to remain relevant, its practitioners need to re-think how health systems are conceptualised, to keep up with rapid changes in how we diagnose and manage disease and use information, and consider factors affecting people's health that go well beyond healthcare systems. The Sustainable Development Goals (SDGs) represent a shifting paradigm in human development by seeking convergence across sectors. They also offer an opportunity for HPSR to play a larger role, given its pioneering work on applying systems thinking to health, its focus on health equity, and the strength of its multi-disciplinary approaches that make it a good fit for the SDG era.Globally, population health is being challenged in different ways, from climate change and growing air pollution and toxic environmental exposure to food insecurity, massive population migration and refugee crises, to emerging and re-emerging diseases. Each of these trends reinforce each other and concentrate their harms on the most vulnerable populations. Multi-level governance, together with novel regulatory strategies and socially oriented investments, are key to successful action against many of the new challenges, with HPSR guiding their design and evolution.The HPSR community cannot be complacent about its successful, yet short, history. Tensions remain about how different stakeholders use HPSR such as the contrast between embedding research within government institutions versus independently evaluating and holding decision-makers accountable. Such tensions are inevitable in the boundary-spanning field that HPSR has become. We should strive to enhance the influence of HPSR by staying relevant in a changing world and embracing the strength of our diversity of disciplines, the range of problems addressed, and the opportunity of the SDGs to ensure that health and social benefits are more inclusive for people within and across countries.