DataWatch. A Profile Of Anesthesia Practice Patterns by Margo L. Rosenbach and Jerry Cromwell

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1 DataWatch A Profile Of Anesthesia Practice Patterns by Margo L. Rosenbach and Jerry Cromwell Unlike many other areas of health care delivery in the United States, anesthesia care is provided by both physicians and nonphysicians, primarily certified registered nurse anesthetists (CRNAs). Although licensure and certification laws require that CRNAs work under the supervision of a physician, direction by an anesthesiologist generally is not required. 1 In many hospitals, CRNAs are the primary anesthesia providers and are supervised by surgeons in the absence of anesthesiologists. 2 The cost differential between the two providers is substantial. CRNAs earn $39,000 annually (excluding fringe benefits but including income from overtime and on-call work) compared to an average net income of $145,000 for anesthesiologists. 3 For every hour spent with a patient (adjusting for differences in work effort), CRNAs earn just 37 percent of what anesthesiologists earn. Thus, significant cost savings can result from policies that encourage the substitution of less costly CRNA time for more costly anesthesiologist time. In this DataWatch, we will demonstrate that CRNAs are indeed very close substitutes for anesthesiologists. As part of a larger study of payment options for CRNAs under Medicare, we gathered information from numerous secondary data sources on the geographic distribution of CRNAs and anesthesiologists, supply trends, and hospital affiliations. We also conducted a survey of 500 CRNAs and 500 anesthesiologists nationwide to gather primary data on work effort, practice arrangements, usual activities, and patient load. Supply Trends Two trends in the supply of anesthesia providers can be documented: a steady increase in the availability of physicians specially trained in anesthesiology, and a leveling off in the number of CRNAs. Whereas in Margo Rostmbach is a senior analyst at the Center for Health Economics Research in Needham, Massachusetts. Jerry Cromwell is vice-president of the center, which was founded in 1980.

2 DATAWATCH there were 13,400 CRNAs and 8,800 anesthesiologists, in 1986 there were 22,500 CRNAs and 19,000 anesthesiologists (Exhibit l). 4 Over this twenty-year period, the number of CRNAs has increased by 68 percent versus a 116 percent increase for anesthesiologists. The Graduate Medical Education National Advisory Committee (GMENAC) declared that anesthesiology would be a shortage specialty in 1990, thus justifying an increase in the number of anesthesiologists. 5 However, both the original GMENAC estimates and subsequent supply forecasts assumed only minimal reliance on the team approach. 6 Although the median Delphi panel concluded that team care should be sig nificantly increased, the advisory panel rejected the Delphi estimates of the prevalence of team care because the number of CRNAs was unlikely to increase sufficiently. Instead, the panel recommended that the number of anesthesiologists be increased to meet the projected shortfall in anesthesia personnel. The number of CRNAs has remained relatively constant since 1984, Exhibit 1 Number Of Anesthesia Providers, United States, Sources: Josephine Heimler, Membership Director, American Association of Nurse Anesthetists, personal communication, December 1986; and Committee on Manpower, American Society of Anesthesiologists, Annual Report, September a These figures represent the number of members in the American Association of Nurse Anesthetists, excluding nurse anesthesia students. b These figures represent the number of members in the American Society of Anesthesiologists, excluding anesthesiology residents.

3 120 HEALTH AFFAIRS Fall 1988 fluctuating between 22,300 and 22,700. One explanation is that accredited nurse anesthesia programs have dropped by over 50 percent from 1980 to 1986, with a 40 percent reduction in the number of graduates. 7 Programs have closed because of the withdrawal of support from anesthesiologists, particularly in academic medical centers with coexisting residency programs. Concerns within some hospitals over program costs, effect of Medicare s prospective payment system (PPS) on hospitals fiscal stability, and potential reductions in the graduate medical education passthrough under PPS have closed programs as well. 8 On the other hand, the number of residents trained in the United States has more than tripled since 1966 and has increased by more than 50 percent since 1980 (Exhibit 2). 9 Concurrently, the proportion of residents receiving their undergraduate training in foreign countries has declined precipitously, from 58 percent in 1972 to 11 percent in These supply trends should concern policymakers for two reasons: the lower cost of CRNAs, and the broad substitutability of CRNAs for anesthesiologists. To the extent that the increasing supply of anesthesiologists will result in the displacement of some CRNAs, anesthesia costs are likely to escalate in the current fee-for-service environment. Exhibit 2 Number Of Anesthesiology Residents And Percentage Foreign Trained, Year Number of residents Percent foreign trained , % , , , , , , , , , , , , , , , , , , , Source: Committee on Manpower, American Society of Anesthesiologists, Annual Report, September 1986.

4 DATAWATCH 121 Geographic Distribution The substitutability of CRNAs for anesthesiologists is demonstrated on a large-scale level in the geographic distribution of the two providers. Exhibit 3 ranks the states according to the rate of CRNAs per capita, ranging from two CRNAs per 10,000 population in South Dakota to 0.22 in Indiana. In absolute terms, the largest numbers of CRNAs are found in Pennsylvania (1,800) and Texas (1,400), accounting for 16 percent of the total. Whereas seventeen states have at least one CRNA per 10,000 population, only one state (Massachusetts) has achieved that rate for anesthesiologists. The lowest per capita rate is found in South Dakota (0.27). Three states California, New York, and Texas account for 28 percent of anesthesiologists, with 13 percent residing in California alone. Exhibit 4 lists the states according to the relative availability of the two providers compared to the national median. For CRNAs the median rate is 0.84 and for anesthesiologists, 0.61 per 10,000 population. In eighteen states, the availability of CRNAs per capita is above the median, but the anesthesiologist rate is below the median. Nine of these states are in the South and six in the North Central region where, in the absence of anesthesiologists, hospitals historically have relied on CRNAs working under a surgeon s supervision. 10 Another eighteen states have an above-average rate of anesthesiologists and a below-average rate of CRNAs. These same states tend to have high physician/ population ratios overall. 11 For example, Massachusetts is number one in anesthesiologists per capita and number three overall in physicians per capita. In only twelve states (all in this category) is the rate of anesthesiologists per capita higher than the rate of CRNAs per capita. We might presume that anesthesiologists (and residents) are substituting for CRNAs, particularly in the academic medical centers. Seven states are above the national median rates for both providers. These states tend to have urban areas that may employ the anesthesia care team concept, as well as rural areas that may rely to a larger extent on CRNAs. In addition, all of these states have large anesthesiology residency programs as well as university- or hospital-based training programs in nurse anesthesia. 12 Finally, at the other extreme, eight states are below the median rates for both CRNAs and anesthesiologists. All of these states have large rural areas and tend to have a below-average rate of hospital beds per capita. 13 Hospital Affiliation The distribution of CRNAs and anesthesiologists varies not only

5 122 HEALTH AFFAIRS Fall 1988 Exhibit 3 Geographic Distribution Of Anesthesia Providers, Ranked BY CRNAs Per Capita a Certified registered nurse anesthetists. b Active members in the American Association of Nurse Anesthetists, as of August c Population figures for 1985, from the Bureau of the Census, Boston Regional Office. d Active members in the American Society of Anesthesiologists, as of December 31, 1986.

6 DATAWATCH 123 Exhibit 4 Distribution Of Anesthesiologists And CRNAs Per 10,000 Population, By State, 1986 Anesthesiologists below median, CRNAS at or above median Alabama Michigan Arkansas Mississippi Delaware Missouri Georgia Nebraska Hawaii North Carolina Idaho North Dakota Kansas South Carolina Louisiana South Dakota Maine West Virginia Anesthesiologists at or above median, CRNAs below median Arizona New Jersey California New York Colorado Oregon Florida Rhode Island Indiana Texas Maryland Utah Massachusetts Vermont Montana Washington Nevada Wisconsin Anesthesiologists at or above median, CRNAs at or above median Connecticut Pennsylvania District of Columbia Tennessee Minnesota Virginia Ohio Anesthesiologists below median, CRNAs below median Alaska New Hampshire Illinois New Mexico Iowa Oklahoma Kentucky Wyoming Source: American Association of Nurse Anesthetists, American Society of Anesthesiologists; and U.S. Bureau of the Census. Note: Median per capita rate for CRNAs is.84 CRNAs per 10,000 population; median per capita rate for anesthesiologists is.61 anesthesiologists per 10,000 population. across states, but also across hospital types, providing more direct evidence of the substitutability of CRNAs for anesthesiologists. Exhibit 5 shows striking differences between hospitals with CRNAs or anesthesiologists working alone and those with a team approach. CRNAs who work alone are located in rural areas, in hospitals averaging fewer than 100 beds, with occupancy rates barely above 50 percent, and with fewer than four operations per day. The facilities are more likely to be publicly owned and less likely to be accredited by the Joint Commission on Accreditation of Healthcare Organizations (JCAHO). In general, the hospital profile for anesthesiologists does not vary according to whether they work alone or with CRNAs except that the team approach is found in hospitals with more beds and more operations per week.

7 124 HEALTH AFFAIRS Fall 1988 Exhibit 5 Hospital Affiliation Of Anesthesia Providers Hospital characteristics Ownership Public, nonfederal Private, not for profit Investor-owned Federal bed size 6-49 beds beds beds 400 or more beds CRNAs working alone 36.7% 13.0% Anesthesiologists and CRNAs Anesthesiologists working alone 7.8% % 1.1% 3.6% Average number of beds JCAHO accreditation 55.1% 95.9% 99.3% Occupancy rate (average) 56.1% 71.8% 68.6% Surgical operations per week (average) Inpatient Outpatient Source: Center for Health Economics Research Anesthesia Practice Survey, 1986; and 1984 American Hospital Association Annual Survey of Hospitals. Usual Activities To what extent do CRNAs substitute for anesthesiologists in performing selected tasks? As part of our survey, we asked CRNAs and anesthesiologists the frequency with which they personally performed certain required activities. Of the four selected pre- and postoperative tasks, both anesthesiologists and CRNAs were most likely to assess patient risk factors or discuss the anesthesia care plan with the patient or family, two components of preanesthetic evaluation (Exhibit 6). Nevertheless, anesthesiologists far outnumbered CRNAs in the proportion regularly performing these tasks. Similar differences were noted in the proportion regularly evaluating the patient in recovery. Many hospitals require an anesthesiologist to discharge the patient from postoperative care. Some hospitals may allow CRNAs to discharge patients with no complications, based on a postoperative scoring system. Neither group obtained informed consent on a regular basis, probably because many anesthesia departments have not yet instituted their own informed consent procedures. Instead, formal anesthesia consent is often part of the surgical consent process. With increasing concerns about anesthetic liability and risk management, separate anesthesia consent procedures are being developed. In the absence of formal anesthesia

8 DATAWATCH 125 Exhibit 6 Regular Performance Of Selected Tasks Task CRNAs Anesthesiologists Evaluate patient risk factors 51.1% a 88.7% a Discuss anesthesia care plan with patient or family Obtain informed consent Evaluate patient in recovery Administer regional anesthesia Insert arterial lines Insert central venous pressure lines Insert Swan-Ganz catheters Source: Center for Health Economics Research Anesthesia Practice Survey, a Percentage of sample reporting that they frequently perform each activity. consent procedures, the anesthetist would note in the medical record that he or she had discussed the proposed anesthesia plan with the patient (including the risks and alternatives) and that the patient had agreed to the plan. About two-thirds of anesthesiologists but less than one-third of CRNAs regularly administer regional blocks. Nearly two-thirds of the CRNAs rarely or never perform regional anesthesia. The delegation of regional anesthesia to CRNAs is opposed by the American Society of Anesthesiologists (ASA), but this may be due to economic rather than quality-of-care concerns. 14 Another controversial area is the placement of invasive monitoring devices by CRNAS. 15 If CRNAs have any role in this area, it is in the insertion of arterial lines. Few CRNAs insert central venous pressure lines or Swan-Ganz catheters. While invasive monitoring is not a frequent activity for either group, clearly anesthesiologists assume the major responsibility. It is important to note that most of these tasks (except invasive monitoring) are more often performed by CRNAs who work alone than by CRNAs who work in a team with anesthesiologists. Simply stated, when a CRNA works alone there is no other anesthetist to perform the task, but when an anesthesiologist is involved less delegation occurs. Moreover, CRNAs who have entered the profession within the past twenty years appear to have more responsibility than their older colleagues in such tasks as administering regional anesthesia, inserting invasive monitoring devices, and evaluating patients in recovery. This may be related to the upgrading of many academic programs from certificate to degree programs. Interestingly, an anesthesiologist s years of experience are also inversely related to performance of certain tasks, notably

9 126 HEALTH AFFAIRS Fall 1988 invasive monitoring. Thus, advances in anesthesia have affected CRNAs and anesthesiologists alike. Patient Mix Anesthesiologists are more likely to perform certain technical tasks on a case, but do they also concentrate more than CRNAs on more complex patients? Our survey gathered information on cases seen during the provider s most recent shift. Each case was classified according to the mix of anesthesia providers, with one-fifth involving a CRNA only, onethird an anesthesiologist only, and one-half including both a CRNA and an anesthesiologist. Exhibit 7 shows selected characteristics by provider type. In summary: (1) patient age averages forty-three to forty-five years regardless of provider type. (2) The average ASA physical status score is higher for the cases in which the two providers work together, compared to cases where they work alone. (3) CRNAs working alone see a higher proportion of emergency cases than the other two groups. This may result from the role of CRNAs in providing in-house anesthesia coverage during evening and weekend hours when anesthesiologists are on call. (4) CRNAs working alone have a larger outpatient surgical caseload (relative to the two groups) and, on average, are involved in shorter procedures, consistent with a greater emphasis on less complex outpatient surgery. Surgical Mix Surgical complexity was compared across the three provider groups by assigning a score to each case based on the type of procedure and patient risk factors. 16 On average, CRNAs working alone performed significantly less complex procedures, with an average complexity of 5.18 versus 5.85 for cases involving an anesthesiologist. These case-mix differences were Exhibit 7 Case-Mix Characteristics CRNA only Anesthesiologist and CRNA Average patient age Average ASA status Emergency cases 16.8% 11.2% 10.7% Outpatient cases 42.5% 39.9% 34.3% Average length of procedure (minutes) Source: Center for Health Economics Research Anesthesia Practice Survey, Anesthesiologist only

10 DATAWATCH 127 found across both obstetric and nonobstetric cases. However, no complexity differences were found between the cases involving an anesthesiologist alone and in a team with CRNAs. Exhibit 8 shows the distribution of cases by surgical complexity. At one extreme, all three groups performed roughly the same proportion of the least complex cases: level three procedures (such as dilation and curettage, circumcisions, and breast biopsies) accounted for 19 to 20 percent of caseloads across the three groups. Anesthesiologists working alone were as likely to perform a level three procedure as CRNAs working alone. When CRNAs collaborated with an anesthesiologist, they were as likely as anesthesiologists working alone to be involved in the more complex cases 6 percent of the cases were over ten anesthesia base units and modifier units (a measure of complexity based on the CPT-4 surgical procedure code and on the patient s age and physical status). In fact, the case-mix distribution was identical for anesthesiologists working alone or in a team with CRNAs. CRNAs working alone were involved in few complex cases, with only 1 percent over ten units and none over sixteen units. This may be due in part to the surgical facilities at hospitals with only CRNAs, as well as the need for more than one anesthetist in very complex cases. Exhibit 8 Complexity Of Procedures, By Type Of Anesthesia Provider Source: Center for Health Economics Research Anesthesia Practice Survey. a Procedure complexity reflects the number of base units assigned to a procedure plus modifiers that take into account extremes of age (below age one, above age seventy) and poor physical status (ASA status of 3, 4, or 5). 3 is least complex, 23 is most complex.

11 128 HEALTH AFFAIRS Fall 1988 Quality Of Care Does CRNAs involvement in anesthesia care have a discernible impact on anesthesia outcomes? In reviewing the literature, we found three studies that examined anesthesia outcomes by provider type. None detected significant differences in anesthesia outcomes among CRNAs versus anesthesiologists. What do we conclude from this finding of no difference? One possible conclusion is that the three studies, taken together, prove that the two groups provide equal quality of care, despite vast differences in training. l8 An alternative explanation is that the two groups do not provide equal quality of care, but methodological flaws in the three studies mask the difference. In particular, the studies may inadequately control for differences in patient severity or may not fully quantify each provider s role in delivering anesthesia care. However, we believe the most persuasive explanation for this null finding is that institutional safeguards assure the quality of anesthesia care, regardless of the provider mix. These mechanisms are extensive. First, licensure and certification assure the qualifications of both provider groups. Second, the JCAHO sets standards for hospital-based anesthesia services, imposing requirements for quality assurance activities as well as supervision of CRNAs. Consistent with JCAHO standards, the two professional societies and many state licensure laws require that facilities develop written guidelines delineating the scope of CRNA practice and the nature of physician supervision. Moreover, anesthesia departments may develop informal triage processes according to an anesthetist s competence (for both CRNAs and anesthesiologists). This could be accomplished overtly through limits on clinical privileges or more subtly through scheduling and assignment of cases. Triage also occurs across hospitals, such that more difficult cases would be referred to tertiary care centers and would be more likely to involve an anesthesiologist, working either with a CRNA, with a resident, or alone. No one would argue that the training of CRNAs and anesthesiologists is comparable, but, in our view, an extensive array of institutional mechanisms exists to enhance the overall quality of anesthesia care. One final piece of evidence is drawn from a case study of the Kaiser- Southern California system. We found extensive heterogeneity in the anesthesia staffing patterns across the nine hospitals. The ratio of CRNAs to anesthesiologists ranged from one to one in one hospital to four to one in two hospitals. The staffing patterns did not appear to be a function of case-mix since the tertiary care facility had a three-to-one ratio. Instead, program differences (such as the presence of an obstetrics epidural program), historical precedent, future expansion plans, and

12 DATAWATCH 129 philosophy of the chief anesthesiologists seemed to account for the differences. Also, Kaiser hospitals are unique in California in using CRNAs as extensively as they do, given the plentiful supply of anesthesiologists. Implications With the growing supply of anesthesiologists and the leveling off of the number of CRNAs, the cost of anesthesia services is likely to increase rapidly in the fee-for-service environment. Patients are not price-sensitive for two reasons: first, they rarely choose their anesthetist, and second, health insurance coverage is quite broad. We have shown that CRNAs do indeed substitute for anesthesiologists, both on the large-scale level across states as well as on the case level across a wide range of procedures and patients. The most important factor influencing CRNA delegation by anesthesiologists is the relative availability of the two providers. 19 However, our evidence also indicates limits on their substitutability. CRNAs do not work alone on the most complex of procedures, nor do they perform the most technical of tasks when an anesthesiologist is involved. Third-party payers should provide strong incentives for the appropriate delegation of anesthesia services using a team approach, that is, CRNAs medically directed by anesthesiologists. Increased delegation results not only in substantial cost savings, but also in profound productivity increases. Supervising nurse anesthetists is estimated to raise anesthesiologists productivity by 20 percent or more, allowing for downtime and scheduling problems. Greater delegation could save approximately $500 million annually in anesthesiologist costs, even allowing for an increase in CRNA costs. 20 However, CRNA delegation can be increased only by reducing payments to anesthesiologists who choose to practice alone, particularly on the least complex cases. Moreover, while productivity gains for effective CRNA delegation should be rewarded, they should not be compensated to the extent that they currently are paying anesthesiologists as if they were fully involved in every case. These two payment reforms, taken together, are a step toward promoting a more efficient mix in the delivery of anesthesia services in this country. This research was supported by Cooperative Agreement No. 18-C-98759/ 1-02 from the Health care Financing Administration. The views and opinions are the authors, and no endorsement by HCFA or the Department of Health and Human Services is intended or should be inferred.

13 130 HEALTH AFFAIRS Fall 1988 NOTES 1. Based on a review of practice statutes in fifty states and the District of Columbia. The authors are indebted to staff of the American Association of Nurse Anesthetists (AANA) for making these statutes available for our study. 2. American Society of Anesthesiologists, Committee on Manpower, The Geographical Distribution of Anesthesia Care Providers in the United States (Chicago: ASA, 1983). 3. Data for CRNAs were obtained from the 1984 annual survey of CRNAs conducted by the AANA. Data for anesthesiologists were obtained from American Medical Association, Socioeconomic Characteristics of Medical Practice 1985 (Chicago: AMA, 1985). 4. Figures for CRNAs obtained from J. Heimler, Membership Director, American Association of Nurse Anesthetists. Figures for anesthesiologists from the American Society of Anesthesiologists, Committee on Manpower, Annual Report (Chicago: ASA, September 1986). 5. Graduate Medical Education National Advisory Committee, Summary Report, Vol. 1, U.S. Department of Health and Human Services Publication no. (HRA)81-651, April M.A. Bowman et al., Estimates of Physician Requirements for 1990 for the Specialties of Neurology, Anesthesiology, Nuclear Medicine, Pathology, Physical Medicine and Rehabilitation, and Radiology, Journal of the American Medical Association 250, no. 19 (1983): C. Zambricki and R.G. Ouellette, Guest Editorial: On Matters of Concern about Nurse Anesthesia Education, Journal of the American Association of Nurse Anesthetists (December 1987): Zambricki and Ouellette, Nurse Anesthesia Education. 9. ASA Manpower Committee, Annual Report. 10. ASA, Geographical Distribution of Anesthesia Providers. 11. American Medical Association, Physician Characteristics and Distribution in the U.S., 1987 ed. (Chicago: AMA, 1987). 12. American Medical Association, Directory of Graduate Medical Education Programs (Chicago: AMA, 1987); and Council of Accreditation of Nurse Anesthesia Educational Programs/ Schools, List of Recognized Educational Programs with Revisions (Current Status as of December 1985), Journal of the American Association of Nurse Anesthetists (December 1985): Ratios of hospital beds per capita were calculated for 1984 based on data from U.S. Department of Commerce, Statistical Abstract of the United States, 1987, 107th ed. (Washington, D.C., 1986). 14. American Society of Anesthesiologists, Position Paper on Regional Anesthesia, 1986 Directory of Members (Chicago: ASA, 1986); and G.W. Ostheimer, Should Regional Anesthesia Be Performed by CRNAs? Regional Anesthesia 8 (1983): Arterial lines are used when blood pressure measurement is required more often than once every minute. Central venous pressure (CVP) lines are used to monitor the adequacy of circulating blood volume to ascertain the need for fluid replacement. Swan-Ganz catheters are used when left heart failure is present or when onset may occur during anesthesia. Insertion of the balloon catheter is delicate, as pulmonary ischemia or infarction may result from improper placement. The Anesthesia Practice Survey asked specifically about the insertion of Swan-Ganz catheters, but it is possible that some anesthetists apply this term generically to pulmonary artery catheters. 16. Anesthesia base units were assigned to each procedure based on the CPT-4 surgical procedure code. Modifier units were added to the base units to take into account extremes of patient age (one unit for under age one or age seventy or older), as well as

14 DATAWATCH 131 poor physical status (one, two, or three units for ASA physical status scores of three, four, or five, respectively). 17. See A.A. Bechtoldt, Committee on Anesthesia Study of Anesthetic-Related Deaths: , North Carolina Medical Journal 42 (1981): ; W.H. Forrest, Outcome The Effect of the Provider, in R.A. Hirsh et al., eds., Health Care Delivery in Anesthesia (Philadelphia: George F. Stickley Co., 1980), ; and J. Gilbert, Outcome Experience and Training of the Anesthetist, in Hirsh et al., eds., Health Care Delivery in Anesthesia, CRNAs typically train for four to six years in certificate or degree programs. Anesthesiologists receive eleven to twelve years of education, including residency training. 19. M. Rosenbach and J. Cromwell, When Do Anesthesiologists Delegate? Discussion Paper (Needham, Mass.: Center for Health Economics Research, 1988). 20. J. Cromwell and M. Rosenbach, The Impact of Nurse Anesthetists on Anesthesiologist Productivity, Discussion Paper (Needham, Mass.: Center for Health Economics Research, 1988).