Many comparisons of international health care spending focus on the structure of the health care delivery system: How the United States tends to provides incentives for doctors providing more costly care. But one other reason that American health care is expensive likely has to do with the country’s health care status. Health policy research has borne this idea out: One recent study that compared health care costs for autoworkers across the country found 37 percent of spending variance was due to how sick or healthy workers were in each area. In Medicare, costs of caring for overweight and obese seniors is rising faster than for the general population. Incentives certainly matter in medicine, but so does the health care status of the population each system is treating.