Based on a study of 174,630 people who were on the wait list for a heart, kidney, or liver from 1999 to 2004, the study showed that those in rural areas were 10% to 20% less likely to get an organ than metropolitan residents. Some gains in distribution equality for minority groups, such as the African-American population, have been reported. However, because most transplant centers are located in cities, the population that lives outside metropolitan areas (about 14%) may continue to struggle to get organ transplants. The researchers, led by Dr. David A. Axelrod, suggest that increasing transplant services in metropolitan facilities may lead to increased access barriers for rural patients. According to Axelrod, “further assessment of the disease burden facing rural residents and the barriers in access to specialty care services is needed to ensure equitable access to life-saving organ transplants.”