Fifty years after the Equal Pay Act, the male-female salary gap has narrowed in many occupations.1 Yet pay inequality persists for certain occupations, including medicine and nursing. Studies have documented salary differences across clinical settings for diverse cohorts of physicians2,3 and higher salaries for male registered nurses (RNs).4-6 In nursing, analyses have not considered employment factors that could explain salary differences,6 have been cross-sectional,4,5 and have not been based on recent data. The objective of this study was to examine salaries of males and females in nursing over time and to include a more recent sample.

Methods

We determined salary trends by gender using nationally representative data from the last 6 (1988-2008) quadrennial National Sample Survey of Registered Nurses (NSSRN) (discontinued in 2008). This mail, electronic, and web survey selected a state-based probability sample of currently licensed RNs from data provided by state boards of nursing with a sample size of more than 30 000 RNs per year and a response rate of approximately 60%. We also used the American Community Survey (ACS; 2001-2013), a household survey with a response rate exceeding 90%, to extend time trends to 2013 and establish that unadjusted salary differences by gender were not limited to NSSRN data. The sample consisted of full-time employed RNs working 50 or more weeks per year and 35 hours or more per week. The outcome variable of annual salary was measured continuously in both surveys.

Using ordinary least-squares regression and employment information in the NSSRN, we assessed how much of the annual salary differences could be accounted for by demographic factors, work hours, experience, work setting, clinical specialty, job position, survey year, state of residence, and other factors. Analyses were performed using Stata version 13.1 (StataCorp) and a 2-tailed probability value of <.05 indicated statistical significance. The study was deemed exempt by a research ethics board.

Results

The NSSRN sample included 87 903 RNs, of whom 6093 (7%) were men, 10 253 (12%) were nonwhite, 58 757 (67%) were married, and 8681 (10%) had a graduate degree. The mean age was 42 years (SD, 10.4 years). The ACS sample included 205 825 RNs, of whom 20 616 (10%) were men, 38 482 (19%) were nonwhite, 134 938 (66%) were married, and 27 842 (14%) had a graduate degree. The mean age was 45 years (SD, 11.4 years).

Both surveys showed that unadjusted male salaries were higher than female salaries during every year (NSSRN, $10 775 [95% CI, $10 243-$11 306], P < .001; ACS, $9562 [95% CI, $9163-$9961], P < .001; Figure 1). No statistically significant changes in female vs male salary were found over time. Using the NSSRN, regression analysis estimated an overall adjusted earnings difference of $5148 (P < .001).

The salary gap was $7678 (95% CI, $5319-$10 037; P < .001) for ambulatory care and $3873 (95% CI, $3144-$4601; P < .001) for hospital settings. The gap was present in all specialties except orthopedics, ranging from $3792 (95% CI, $802-$6781; P < .001) for chronic care to $6034 (95% CI, $4175-$7893; P < .001) for cardiology. Salary differences also existed by position, ranging from $3956 (95% CI, $2174-$5737; P < .001) for middle management to $17 290 (95% CI, $11 690-$22 891; P < .001) for nurse anesthetists (Figure 2). The model accounted for half of the variance in salaries (R2 = 0.46).

Discussion

Male RNs outearned female RNs across settings, specialties, and positions with no narrowing of the pay gap over time. About half of the gap was accounted for by employment and other measured characteristics. This gap is similar in magnitude to the salary differences found for physicians.2,3

Study limitations include survey data that are subject to reporting biases and the lack of detail regarding specialties and positions in the NSSRN.

The roles of RNs are expanding with implementation of the Affordable Care Act and emphasis on team-based care delivery. A salary gap by gender is especially important in nursing because this profession is the largest in health care and is predominantly female, affecting approximately 2.5 million women. These results may motivate nurse employers, including physicians, to examine their pay structures and act to eliminate inequities.

Section Editor: Jody W. Zylke, MD, Deputy Editor.

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Corresponding Author: Ulrike Muench, PhD, RN, Department of Social and Behavioral Sciences, University of California, 3333 California St, San Francisco, CA 94118 (ulrike.muench@ucsf.edu).

Author Contributions: Dr Muench had full access to all of the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis.

Study concept and design: All authors.

Acquisition, analysis, or interpretation of data: Muench, Sindelar, Buerhaus.

Drafting of the manuscript: All authors.

Critical revision of the manuscript for important intellectual content: All authors.

Statistical analysis: Muench, Busch.

Obtained funding: Muench.

Administrative, technical, or material support: Muench, Busch, Buerhaus.

Study supervision: Sindelar, Busch.

Conflict of Interest Disclosures: The authors have completed and submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest. Dr Buerhaus reported receiving payment for lectures from a variety of organizations, associations, universities, and groups; and being appointed chair of the National Health Care Workforce, which was established under the Affordable Care Act, but has not begun any work yet. No other disclosures were reported.

Funding/Support: This study was in part supported by a grant from Sigma Theta Tau, Delta Mu Chapter.

Role of the Funder/Sponsor: Sigma Theta Tau had no role in the design and conduct of the study; collection, management, analysis, and interpretation of the data; preparation, review, or approval of the manuscript; and decision to submit the manuscript for publication.

Additional Information: We dedicate this study to Donna Diers, PhD (Yale School of Nursing), who died during the early stages of this research.