From the Journal of the American Medical Association:
Changes in Financial Burdens for Health Care
National Estimates for the Population Younger Than 65 Years, 1996 to 2003
...In 2003, individuals with higher-than-average risk of incurring high total burdens included poor and low-income persons and those with nongroup coverage, aged 55 to 64 years, living in a non-metropolitan statistical area, in fair or poor health, having any type of limitation, or having a chronic medical condition. Applying our definition of underinsured to the insured population, an estimated 17.1 million persons younger than 65 years were underinsured in 2003, including 9.3 million persons with private employment-related insurance, 1.3 million persons with private nongroup policies, and 6.6 million persons with public coverage.
Conclusions Our analysis identifies patients at greatest risk of health-related financial burdens that may adversely affect their access and adherence to recommended treatments. Our study also highlights the high costs associated with nongroup health insurance policies....
JAMA -- Abstract: Changes in Financial Burdens for Health Care: National Estimates for the Population Younger Than 65 Years, 1996 to 2003, December 13, 2006, Banthin and Bernard 296 (22): 2712