The size of the registered nurse (RN) workforce has surpassed forecasts from a decade ago, growing to 2.7 million in 2012 instead of peaking at 2.2 million as predicted. One less-noticed factor in this “nursing boom” is the decision by a growing number of RNs to delay retirement.

According to a new study being released today as a Web First by Health Affairs, among registered nurses working at the age of fifty from 1991 to 2012, 24 percent continued working as of the age of sixty-nine. This compared to 9 percent of RNs still working at the age of sixty-nine in the period from 1969 to 1990.

Authors David Auerbach, Peter Buerhaus, and Douglas Staiger also found that as RNs tend to shift out of hospital settings as they age, employers may welcome the growing numbers of experienced RNs seeking employment in other settings. Auerbach is affiliated with the RAND Corp. in Boston, Massachusetts; Buerhaus with Vanderbilt University’s Institute of Medicine and Public Health in Nashville, Tennessee; and Staiger with Dartmouth College in Hanover, New Hampshire.

Information about the RNs’ ages, employment status, and hours worked, and the age and size of the U.S. population, was obtained from the Current Population Survey and the American Community Survey. The authors examined RN workforce data for the period 1969–2012, with respondents’ ages ranging from 23 to 69.

“In 2012 an employed fifty-year-old nurse would be expected to work an average of 14.0 more years, whereas a comparable RN before 1990 would have been expected to work another 11.5 years,” conclude the authors.

“This increase has been partly responsible for the continued growth in the RN workforce…. In addition, it may have contributed to some of the difficulty that the recent surge of new RNs has had in finding the jobs they expected.”

Looking ahead, the authors expect that changes in care delivery brought about by the Affordable Care Act could increase the demand: “Older RNs are far more likely to work outside of the hospital than younger RNs are—and thus the larger number of older RNs seeking nonhospital employment could be a welcome development for nonhospital organizations that are seeking RNs.”

This study, which was supported by the Gordon and Betty Moore Foundation, will also appear in the August issue of Health Affairs.