A Comparison of Changes in the Professional Practice of Nurse Practitioners, Physician Assistants, and Certified Nurse Midwives:  1992 and 2000

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This page: Chapter 6.  Certified Nurse Midwives | Chapter 7.  Factors Related to Professional Practice Indices

Chapter 6.  Certified Nurse Midwives

This chapter summarizes the original and new professional practice indices for CNMs for the fifty States.  It includes the following subsections:

• Introduction
• The Original Practice Environment Index for CNMs
• The New Professional Practice Index for CNMs
• Conclusions
• Detailed scoring sheets for CNMs for each of the 50 States can be found in Appendices C and F.

Introduction

The profession of midwifery has a history spanning both centuries and geography and is arguably the most publicly known of the professions that are subjects of this research. CNMs are healthcare providers who combine the skills of nursing with the competencies of midwifery. Midwives have a special focus on childbirth guided by an orientation that birth is a normal physiological process not an illness.

Presently, nurse midwives provide birthing services but their practice is also augmented by skills obtained in advanced education to include well women health care and educational services as well as family planning services. Nurse midwives attend just under 10 percent of all vaginal births in the United States.^[33] Contrary to public perception, 99 percent of these births occur in a hospital or birthing center with less than 1 percent occurring in homes.^[34]

Nurse Midwives are currently licensed in every State. Some States regulate nurse midwifery as a separate profession while others regulate the profession as a special class of nurse in advance practice nurse legislation.  In most States, the Board of Nursing governs the profession. Nurse Midwives are separately regulated by a Board of Midwifery in only two States, Utah and New York. The legal status and scope of practice of midwives varies significantly across the 50 States and the District of Columbia.

The Original Practice Environment Index for CNMs

The original CNM practice environment index developed by Sekscenski et al for 1992 was based on three broad criteria and point allocations reflecting the then present practice environment for the profession. The specific criteria and point allocations used in creating the index were Legal Status (Maximum Score  = 20);  Reimbursement (Maximum Score = 40); and Prescriptive Authority (Maximum Score = 40). The detailed point allocations for the original index for CNMs are presented in Table C-3 in Appendix C.

The original professional practice index scores for CNMs for the 50 States resulting from the criteria in Table C-3 in Appendix C are summarized in Table 6-1. The scores show a definite trend toward greater professional practice options across the fifty States and the District of Columbia between 1992 and 2000. The increases in the index scores indicate greater professionalization, socialization, and standardization of professional practice for CNMs over the last decade.

The New Professional Practice Index for CNMs

To better reflect the subtle differences that often exist in professional practice across the 50 States, a new index was developed as part of this study that incorporates more criteria and more variability in the scores assigned. The new professional practice index more accurately reflects the practice environments of CNMs across the U.S. in 2000.

Table 6-1 shows that most States scored lower on the new 2000 index than on the original 2000 index. This is an indication of the impact of the changing health care delivery system which places greater demands and requirements on health professionals in both clinical practice and practice management. For example, statutes defining Managed Care Organizations added new reimbursement options for CNMs between 1992 and 2000 in many States.

Discussion

The scores on the original CNM practice environment index reveal a trend toward more practice options for CNMs across the fifty States and the District of Columbia between 1992 and 2000. The scores indicate the trend towards greater professionalization, socialization, and standardization of the CNM profession over the last decade. Additional analyses of the index scores are described and summarized in Chapter 7.

As is true with many such indices, the true differences that underlie small differences in the scores are generally very small. Thus, States that are close on any the indices are not significantly different in their professional practice. The authors have applied a qualitative overlay to the new index scores to identify States they believe provide Excellent, Favorable, Acceptable, Limiting, and Restrictive environments for CNMs. These are not hard-and-fast terms or categories, and they are provided only to help readers to characterize the practice environments in the different states in a more qualitative way. The terms do generally conform to characterizations of the practice environments in States by knowledgeable CNMs.

Comparisons of individual CNM professional practice scores on a State-by-State basis should be made with caution. The scores reflect general, not particular, conditions in the State regulatory environments. Comparing one State with another on the Sekscenski index may not fully indicate the similarities or differences in actual practice patterns. The index is a good indicator of the trend toward broader practice environments, but it does not effectively capture the detailed variations in State requirements.

Chapter 7.  Factors Related to Professional Practice Indices

This chapter summarizes a series of statistical analyses performed to estimate the extent to which different factors and variables are related to the professional practice indices developed in this study.  It includes the following subsections:

• Introduction
• Factors Related to Professional Practice Indices
• Other Patterns and Relationships
• Conclusions

Introduction

The professional practice indices presented in the preceding chapters have some limited intrinsic value for policy makers interested in the three professions, but much of the interest by health policy makers in these statistics comes from understanding how the indices are related to the numbers of practitioners in the three professions and, ultimately, to access to patient care, especially for underserved populations.

This chapter examines several hypotheses related to the professional practice indices for NPs, PAs, and CNMs, the numbers of professionals per capita for the three professions in the 50 States, and several measures related to access to and the delivery of care. Given the changes that have taken place in health care and the health workforce in the 1990s, three general patterns were hypothesized with respect to each of the three professions.

• The legal scopes of practice (as measured by the indices described above) increased significantly between 1992 and 2000 across the 50 States, indicating increasing acceptance of the professions by physicians, the public, and government regulators.
• Variations in the professional practice declined between 1992 and 2000, indicating a general convergence or standardization of professional practice environments across the States.
• Positive relationships (i.e., correlations) exist between the professional practice indices and the relative supply of practitioners for the three professions (as measured by practitioner per capita ratios).

In addition to these three key hypotheses, the authors performed supplementary analyses of the relationships between the three professions and physicians (i.e., PAs with all physicians, NPs with all physicians, and CNMs with ob-gyns). Of particular interest is whether or not the three professions and physicians have a complimentary relationship or a substitutive relationship with one another.

Analyses were also performed to assess the extent of relationships between the professional practice indices and other measures of the health care system and the health status of the population. These include HMO penetration in the States and the percentages of States’ populations living in Health Professions Shortage Areas (HPSAs).

Data and Methods

The data set compiled for this study includes a number of variables summarized in Table 7-1. The original index for 2000 was developed by identifying specific criteria and weighting schemes that would permit replication of the 1992 indices, and then applying these criteria and weights to conditions in 2000. Because some of the historical files related to the earlier study were not available, it was not possible to identify criteria that permitted replication all of the1992 scores. Several of the criteria used by Sekscenski required application of judgment about points assigned for certain conditions, and the authors were unable to devise a single weighting scheme that would successfully replicate the earlier indices for all the States. Also, the authors did not have complete copies of all statutes and regulations in force in the 50 States in 1992, which complicated the task of assigning scores for specific elements of the indices. Despite these limitations, it was possible to replicate the 1992 scores for 45 of the 50 States.

The data presented in Table 7-2 summarize the original index scores as reported in their NEJM article, along with the results of applying the authors’ best choice of criteria uniformly for all 50 States for 2000. Thus, State scores for 1992 are based on internally consistent criteria and definitions, as are the State scores for 2000. While there is some question about the validity of comparisons of 1992 and 2000 indices, the fact that the authors were able to replicate 90 percent of the State scores of 1992—and that in the cases where replication was not possible the differences were negative—provides a basis for confidence in the comparisons.

The practitioner counts for 1992 were estimated from the article by Sekscenski et al. Counts for later years were obtained from other sources that appear to be the most reliable as indicated in Table 7-1. The data for PAs is believed to be generally accurate and comparable over time. The data for NPs and CNMs, while improving in recent years, have gaps in the early 1990s that will require attention before reliable year-to-year comparisons can be made for this time period.

The primary analysis tool used in this study was Spearman’s rank order correlation. This permits comparisons with Sekscenski et al [1994] which also used this technique. The paired t-test was used to compare average values of the Sekscenski indices for 1992 and 2000. In addition, the F-test was used to compare the variances of the Sekscenski indices in 1992 and 2000. In all cases, an alpha level of 0.05 was used to test statistical significance. All tests were performed using SPSS for Windows version 11.0.

Results

Trends in Professional Practice Indices from 1992 to 2000

Table 7-2 summarizes the information in Tables 4-1, 5-1, and 6-1. It shows clearly that on average the 50 States experienced statistically significant increases in the original practice environment indices for all three professions. This is a clear indication that the professional practice options for all three professions expanded between 1992 and 2000.

Table 7-2 also shows that the standard deviation of the original scores across the States was smaller in 2000 than in 1992 for all three professions, and that the difference was statistically significant for NPs and PAs. This is an indication that there has been a general convergence of the professional practice across the 50 States between 1992 and 2000, especially for NPs and PAs.

Table 7-3 presents the three major components (legal status, reimbursement, and prescriptive authority) of the new professional practice indices for NPs, PAs, and CNMs for all 50 States and the District of Columbia for the year 2000. This reveals insights about why one State may have a larger or smaller index for a profession than another State. The table shows that the average overall new index scores for NPs, PAs, and CNMs for 2000 were 74.7, 74.1, and 69.6, respectively, out of a possible total of 100. These scores are significantly lower than the respective original index scores, reflecting the fact that additional options and criteria have been included in the new indices. Readers interested in more detail about the new scope calculations for NPs, PAs, or CNMs may refer to Appendix E, D, or F, respectively.

Comparisons of scores across the three professions, either on average or for individual States are not appropriate. The three indices are based on different criteria and weighting schemes and are not designed to serve as a standard for comparing the professions.

The gaps between the “optimal” scores and the average scores reveal that opportunities for States to increase the index scores for the three professions are generally greatest for prescriptive authority and legal status, and least for reimbursement. The lower a component score for a State below the “optimal”, the greater the opportunity to increase the index through appropriate adjustment in the corresponding criteria.

The standard deviations of the component scores for the new indices show greater variability in scores across the States for prescriptive authority than for legal status and reimbursement. Comparisons of the standard deviations for the components of the three original indices were not made because of difficulties in replicating the 1992 indices for five States.

Numbers of Practitioners

Table 7-4 shows the increases in the numbers of NPs, PAs, and CNMs per 100,000 population    that occurred between 1992 and 2000. Despite some data limitations for the earlier years, the estimates show that the growth has been dramatic, with NPs per capita growing by 190 percent, PAs per capita growing by 70 percent, and CNMs per capita growing by 65 percent over the 8 year period.

Relationships Between the Professional Practice Indices and Numbers of Practitioners

An analysis of the relationship between the three components of each index for the three professions (legal status, prescriptive authority, and reimbursement) across the professions showed positive correlations among the components professional practice indices across States in 2000 (Table 7-5). States with favorable prescriptive authority for PAs also had favorable prescriptive authority for NPs and CNMs. For legal status and reimbursement, NP scores were significantly correlated with CNM scores, while PA scores were not significantly correlated with either NP scores or CNM scores.

Table 7-5

Correlations of Components of the Professional Practice Indices Across the Three Professions
(Coefficients are Spearman rank-order correlations across the 50 states.)

*  = significant at the 0.05 level
** = significant at the 0.01 level

Sekscenski et al found that favorable practice environments, as measured by their practice environment indices, were strongly positively correlated with numbers of the corresponding professionals. This study confirmed this relation for both 1992 and 2000 for all three professions. Table 7-6 shows the Spearman rank order correlations between the 1992 scope indices and 1992 practitioners per 100,000 population, and between the 2000 scope indices and 2000 practitioners per 100,000 population. These correlations confirm that higher professional practice indices are associated with greater numbers of practitioners per capita for all three professions.

Table 7-6 also shows that the professional practice indices are not significantly correlated with the numbers of physicians per 100,000 population for the corresponding years. This is an indication that states with relatively large (or small) numbers of physicians per capita do not have unusually high (or low) professional practice indices.

Table 7-6
Correlations Between Original Professional Practice Indices and Professionals per Capita, 1992 and 2000
(Coefficients are Spearman rank-order correlations across states.)

1992

2000

 ⁺  = Sekscenski index from the original study
 *  = significant at the .05 level
 ** = significant at the .01 level

Relationships Between the Three Professions and Physicians

The nature of the relationship between the three professions and their physician counterparts typically involves some level of dependency on the part of the three professions. PAs work under the supervision of physicians, and most NPs and CNMs work under some formal collaborative or supervisory agreement with physicians. These supervisory and collaborative working relationships suggest a positive correlation between the numbers of physicians and the numbers of the three professions.

There are a variety of factors that influence these relationships, including organizational arrangements, reimbursement policies, historical trends, etc. When the changes in the professions are as dramatic as they have been for NPs, PAs, and CNMs, some of the usual patterns and relationships may be altered. Nevertheless, this preliminary analysis appears to support the presence of a supportive relationship between the three profession and physicians.

If a substitutive relationship existed, one would expect a negative correlation between the physicians per capita and practitioners per capita for that profession, i.e., that States with relatively fewer physicians per capita had relatively more NPs, PAs, or CNMs per capita. Table 7-7 shows no evidence of such a substitution effect. In fact, the data show a statistically significant positive correlation between NPs per capita and physicians per capita, and between CNMs per  capita and Ob-Gyns per  capita in 2000.

Table 7-7

Correlations Between NPs, PAs, and CNMs per Capita and Their Counterpart Physicians per Capita, 2000
(Coefficients are Spearman Rank-Order Correlations)

*  = significant at the .05 level
** = significant at the .01 level

Other Patterns and Relationships

Relationship of Professional Practice Indices to Access to Care

Since one of the stated goals of the programs that originally launched both the PA and NP professions was to increase access to care, it is of interest to assess the extent to which these goals have been achieved. Unfortunately, current national data systems are not able to assign members of the three professions to services provided to underserved populations or to geographic regions identified as shortage areas. The best that can be done at present for all 50 States is to compute correlations between the percentages of  population residing in Health Professions Shortage Areas (HPSAs) and the scope indices and the numbers of practitioners per capita for the respective States.

* Correlation is significant at the .05 level (2-tailed).
** Correlation is significant at the .01 level (2-tailed).

** Correlation is significant at the .01 level (2-tailed).

General Acceptance of Non-Physician Clinicians.

To get a sense of the extent to which different States have accepted the professions which work closely with physicians, a composite index (equal to the sum of the three new index numbers for 2000) was created. This new index, which is based on all three professions, is not meant to relate to professional practice. It is meant solely to reflect the general acceptance of the professions by government regulators. Oregon had the highest score on this composite index, and South Carolina had the lowest.

This composite index was then translated into a five point scale that rated the general acceptance levels of these non-physician clinicians in the 50 States and the District of Columbia from high acceptance to low acceptance. The results of the translation into the five point scale are displayed in the map in Figure 7-1. The States with the highest general acceptance for the three professions were scattered around the country with higher representation in the Northeast and Northwest, while the lowest general acceptance of the three professions was focused in the Southeast.

[D]

Professional Practice Component Scores

Table 7-10 presents the scores for the three broad components of the new professional practice indices for the three professions in each of  the fifty States and the District of Columbia. Interested readers can use these data to better understand the nature of the practice environments for the three professions in specific States.