Peter Buerhaus of Vanderbilt University School of Nursing, Douglas Staiger of Dartmouth University and David Auerbach of the Congressional Budget Office said the demand for registered nurses is expected to continue to grow at 2 percent to 3 percent per year.

The supply of registered nurses is expected to grow very little as large numbers of nurses begin to retire or leave work.

By 2020, the U.S. shortage is estimated to be 285,000 full-time nurses and reach 500,000 by 2025.

Inadequate nurse staffing in hospitals is associated with reductions in hospital bed capacity, delays in the timeliness of patient care, longer length of stay by patients, interruptions in care delivery processes and increased risk of adverse patient outcomes including mortality, the researchers said in a statement.

The findings are published in the "The Future of the Nursing Workforce in the United States: Data, Trends and Implications."