Figure 1.

Stratification of health risk within a population. Patients with “severe health risk” represent the 5–20% of the primary care population with the highest needs and costs. These are the patients most likely to benefit from intensive primary care services. Standard continuity primary care works best for those with moderate to high risk. The majority of the population, who are at low health risk, require only routine preventative care and episodic low acuity acute care.