Executive Summary

Common pressures shape health-system design choices in the United States and around the world.  Commonalities in problems encountered suggest that solutions—or at least principles underlying those solutions—may also be generalizable. NYC Health + Hospitals leaders developed a strategy around population health that draws on this. Four principles undergird the strategy: identifying and stratifying an attributed population; grounding in high-quality, community-based care; meeting patients where they are, both physically and in terms of their health trajectory; and using data to guide care delivery and drive improvement.  In many cases, local health systems are already operationalizing one or more of these principles, but rarely are all four being put into action.

Convergent evolution occurs when similar environmental pressures produce similar adaptations in organisms from different evolutionary lineages. For example, the wings of insects, birds, and bats are similar in structure and share the same function — but evolved independently. In the same way, changes occurring among health systems across the world can be viewed through the lens of convergent evolution.

The environmental pressures shaping health system design span shifting pathologies and shifting political priorities. Between 1990 and 2016, noncommunicable diseases such as cancers and mental illness became the greatest cause of disease burden worldwide, as measured by disability-adjusted life years, a trend likely to continue due to aging populations.  Growing evidence demonstrates that social determinants of health, such as housing and education, are at least as important as medical services in generating health outcomes. At the same time, financing for health is moving from paying for services rendered to channeling spending according to effectiveness in improving outcomes.  Finally, a commitment to universal health coverage (UHC) — individuals and communities receiving the health services they need without suffering financial hardship — has gained momentum, with all United Nations member states pursuing UHC by 2030​ as part of the Sustainable Development Goals.

Global Principles

These common evolutionary pressures shape system design choices in the United States and around the world.  Commonalities in problems encountered suggest that solutions — or at least principles underlying those solutions — may also be generalizable. At NYC Health + Hospitals, the largest public healthcare system in the United States, I have helped architect a strategy around population health, defined as a more proactive approach to addressing avoidable human suffering.  Four principles undergird the strategy: identifying and stratifying an attributed population (i.e., the population they’re responsible for); grounding in high-quality, community-based care; meeting patients where they are, both physically and in terms of their health trajectory; and using data to guide care delivery and drive improvement.  In many cases, local health systems are already operationalizing one or more of these principles, but rarely are all four being put into action.

Insight Center

First, local health systems must identify the group of patients for whom they are accountable.  While this attribution of patients to clinicians — for instance through “accountable care organizations” in the United States — may seem straightforward or mundane, it is fundamental to systems setting up care models that are not solely contingent on patient visits.  For example, what is the right locus of accountability for patients who only seek acute care, such as through the emergency department, or who do not seek needed care at all, whether because of discrimination, or unaffordability, or lack of health literacy?  Once an attributed population is identified, health systems should stratify patients into groups based on risk of adverse outcomes.  In the same way we triage hospitalized patients into intensive care, step-down units, and general wards, health systems should risk-stratify attributed patients to ensure that resources are appropriately directed to patients according to need.  For instance, as part of a general move toward regionally integrated care in the United Kingdom, a clinical alliance in Nottinghamshire uses predictive modeling to identify patients at elevated risk for hospitalization and provides them with preventative care, such as “virtual wards” providing multidisciplinary, intensive outpatient services.

Second, effective health systems are increasingly grounded in high-quality community-based care.  Of the 218 essential, cost-effective interventions identified by the Disease Control Priorities Network, 140 are delivered through primary care centers or community- and population-based approaches, rather than through hospitals.  In Xiamen, a city in southeastern China, the growing prevalence of chronic diseases led to a new model for primary care known as Joint Management by Three Professionals: specialists who determine care pathways, generalists who implement them, and community health workers responsible for health education, including through home visits. Community health worker programs are particularly emblematic of convergent evolution, having arisen in diverse contexts, including as primary care extenders in India and sub-Saharan Africa; community members of family health teams in Brazil and Costa Rica; promotores de salud (health promoters) at the Mexican border; and as a standardized intervention to reduce hospitalizations for low-income patients in the United States.

Third, and in part due to the evolution toward community-based care, health systems around the world are starting to “meet patients where they are,” both physically and in terms of their health trajectory.  Technology — particularly telehealth such as text-messaging and phone or video consultations —enables the delivery of care remotely. For example, mobile technology supports thousands of community health workers delivering perinatal care across rural Liberia, facilitating escalation of childbirth care to the nearest health facility when indicated. Meeting patients where they are also refers to integrating physical health services with behavioral health and social services. Depressive disorders cause greater disability than any form of cancer worldwide, but are often neglected by health systems. Meanwhile, the growing recognition that social factors like educational attainment often predominate in determining health trajectories is leading health systems to partner with social service agencies to address root causes of illness. In Quebec, Canada, such partnership is facilitated by a whole-of-government approach to health, enshrined in a Government Policy of Prevention in Health, with specific targets such as reducing by 10% the gap in premature mortality between the lowest and highest socioeconomic groups in the province.

The fourth principle common to convergent health systems is using data to guide care delivery and drive improvement. Valid, actionable data is lifeblood for health systems to both motivate change at the frontlines of care and to monitor overall performance. One example is the use of “data cascades” to illuminate gaps across a care continuum. HIV data cascades have been used for decades to target areas of improvement: for instance, charting prevalent HIV cases against those HIV patients who complete a first appointment demonstrates gaps in engagement. The concept of data cascades can be extended to noncommunicable diseases, such as diabetes and substance use disorders. And health systems can leverage the cascading of data in a different sense: linking system-level, facility-level, provider-level, and patient-level data to show how specific patients with uncontrolled blood pressure, for example, relate to the overall performance of the system on hypertension control. These two dimensions of data cascades can be incorporated into a parsimonious set of measures spanning health and financial outcomes for a system to track and hold itself accountable to.

Challenges and Opportunities

Global travel has enabled unprecedented species transfer across the world: pigs from Polynesia now share a common ecosystem with American cutthroat trout. Biologists have termed this the “New Pangaea.”  In the life sciences, a New Pangaea is often invoked to describe the decline in biodiversity associated with global interconnectedness. This may well serve as a warning for thinking about convergent evolution of health systems. Despite global coordination opportunities, the focus of health systems must remain on people and patients, a local accountability.

Local health systems often simply do not yet have the capacity to deliver longitudinal care. A study of noncommunicable disease service availability and readiness in Bangladesh, Haiti, Malawi, Nepal, and Tanzania found that less than five facilities in each country were ready to provide care for diabetes, cardiovascular disease, and chronic respiratory disease. Shortages of trained health workers and essential medicines were critical limitations, particularly in rural areas.  Defects in the quality of health care delivered worldwide span underuse, inappropriate use, and overuse.  A National Academies of Science, Engineering, and Medicine study estimated that between 5.7 million and 8.4 million deaths occurred annually from poor quality of care in low- and middle-income countries.

The example of India lays bare both the challenges and opportunities inherent to a convergent approach. The health workforce is heterogeneous, including lay health workers and unqualified clinicians. Out-of-pocket expenditures comprise approximately two-thirds of health spending, leading to about 90 million Indians becoming impoverished due to health care costs each year.  India is navigating a set of fundamental health policy choices, such as the balance between national and local control, and how to invest in the most cost-effective interventions.

Yet the global principles enumerated above can help forge common solutions — in some cases allowing for a saltatory effect in places like India. There may be an opportunity to leapfrog health financing pitfalls encountered in high-income countries; for instance, setting up reimbursement schemes that discourage low-value care, such as overuse of imaging for back pain. Similarly, as surgical capacity increases in low-income countries, a focus on quality in childbirth care would allow them to avoid unnecessary caesarean sections prevalent in high- and middle-income countries. Reciprocally, the high volume of patients seen in Indian medical centers — for example for cataract surgery — has yielded gains in operational efficiency that holds lessons for places grappling with cost containment, as in the United States.  Global convergence affords a chance to leverage economies of scale for lower-cost, higher-quality interventions, and could facilitate more rapid diffusion of innovation across different local contexts.