ACO — for accountable care organization — is by now a familiar acronym within the healthcare industry and among all Americans who have followed the steady implementation of the Affordable Care Act.

Easily described but very challenging to operationalize, ACOs rely on effective partnering among healthcare providers of all shapes and sizes — health systems, hospitals, clinics, physician practices, urgent care centers — to collectively share responsibility for the health of a population of individuals and accountability for the cost of that care.

An ACO’s success is measured in terms of “value,” i.e., high quality, cost-effective healthcare for the population.

With my colleagues in the rapidly growing field of Population Health, I welcome the introduction of ACOs on the U.S. healthcare landscape.

But, as is often the case, the devil is in the details.

For hospitals in particular ACOs call for new strategies and a new world view.

The first question I would ask a hospital is, “What does it mean to manage a population?”

Over the past couple of decades, hospitals have made great strides in reaching out to the communities they serve — for example, they have acquired great expertise in setting up mobile mammography units and hypertension screenings — but this is not what it means to “manage a population.”

The next question I would ask is, “Who manages the health of that population?”

Hospitals employ talented people who skillfully plan and implement community health fairs — but this is not what it means to “manage the health of the population.”

As hospitals and health systems across the country explore their options for becoming ACOs, they are beginning to grapple with these questions, and their answers are reflected in job descriptions.

For the past month, a steady stream of job descriptions (from hospitals and health systems) has come across my desk listing oversight of “population health” as a chief responsibility.

Reviewing each of these, it becomes clear which organizations have considered the questions carefully and answered them accurately.

For example, organizations that believe they can simply transform the quality improvement team into a population health management program are likely to miss the mark.

On the other hand, organizations that place responsibility for population health management at the C-Suite level are likely to be on the right track.

These job descriptions show a deeper understanding of population health management and a heightened appreciation for what it entails, and examples of responsibilities include:

• Developing cost-effective clinical protocols for high cost/high utilization conditions across the provider system
• Formulating healthcare service utilization and cost forecasts for select patient populations
• Identifying high-risk members in the population and providing care management activities
• Developing the full continuum of care for the population, coordinating care across it, and assisting with transitions required by payment reform

Combined with key goals and expectations (e.g., communicating population health vision to all stakeholders, proactively managing one or more populations, eliminating silos, planning and managing care across the network, developing clinical protocols for five to 10 of the most costly conditions), these organizations have built strong population health foundations into their job descriptions.

Bottom line: accountable care and population health go hand in hand, and they are here to stay.

My hat is off to the hospitals and health systems that have begun to lay the groundwork for population health management by answering the two seemingly simple questions: “What does it mean to manage a population?” and “Who manages the health of that population?”

David B. Nash is founding dean, Jefferson School of Population Health, Thomas Jefferson University and blogs at Nash on Health Policy and Focus on Health Policy.