| ICDCode | Description |
| REF.1 | Definitions of sources and survey data used in the IPD (NHDS, NAMCS, NHAMCS, NSAS, etc.) |
| REF.79 | Pharmaceutical market; biotechnology market |
| REF.80 | International healthcare systems; physician supply; physician specialty |
| REF.81 | Insurance coverage; health insurance; uninsured population |
| REF.82 | Aging and associated health conditions in the geriatric population |
| REF.83 | Expenditures for health; health care costs; national health expenditure |
| REF.84 | Demographics; population segments (e.g., sexual orientation, race/ethnic groups, etc.); population growth; aging trends |
| REF.85 | Vital statistics; mortality; life expectancy |
| REF.86 | Disease burden; notifiable diseases; chronic diseases |
| REF.87 | Internet use |
| REF.88 | Alternative medicine; alternative health care; complementary and alternative medicine (CAM); dietary intake |
| REF.89 | Ambulatory medical care; outpatient visit; ambulatory surgery |
| REF.90 | Reproductive health care services and delivery |
| REF.91 | Veteran population (Veterans Administration, Veterans Affairs) |
| REF.92 | Emergency department |
| REF.93 | Medicaid |
| REF.94 | Medicare |
| REF.95 | Nursing home care (long term care facility); long-term acute care; residential care facility (assisted living) |
| REF.96 | Physical disability |
| REF.97 | U.S. health care, managed care |
| REF.98 | Home health care services; hospice care services |
| REF.99 | Utilization rates for healthcare services; health care utilization |