The second stage involved a meeting to reach group consensus. 3. The third stage involvedindependent judgments based on the results of the group session ...
Nurse Practitioner and Physician Assistant Practices in Three HMOs: Implications for Future US Health Manpower Needs JONATHAN P. WEINER, DRPH, DONALD M. STEINWACHS, PHD, AND JOHN W. WILLIAMSON, MD Abstract: This study empirically examines the practices of non-physician providers (NPPs) within three large competitive health maintenance organizations (HMOs), as well as the physicians' and NPPs' views regarding the ideal role of NPPs. These roles are compared with NPP delegation patterns incorporated in the modeling methodology developed by the Graduate Medical Education National Advisory Committee (GMENAC). GMENAC recommended relatively high levels of delegation by physicians to NPPs. One of the
HMO sites made use of NPPs at rates even higher than GMENAC's national ideals, while the rates at the other two were lower. The normative ideals for pediatric NPPs developed at each HMO were consistently higher than their actual roles. Concerns with acceptance and the role of NPPs are clearly no longer issues. Instead, the limits on NPP involvement appear to relate to considerations of costs, availability, and the increasing numbers of physicians competing for similar opportunities. (Am J Public Health 1986; 76:507-511.)
Introduction
The approach used by GMENAC to determine requirements was based largely on biological need, in which parameters of the model were estimated normatively for individual morbidities. The basic components of the model for each diagnostic group included: * incidence/prevalence of the condition in 1990; * the percentage of affected people requiring care; * the percentage of patients who should be treated by each specialty; * the ideal number of visits per episode, or per year; and * the percentage of all visits that should be "delegated" to NPPs. Summing across all conditions for the entire population, the total national requirement for physicians was estimated by dividing the needed number of physician (non-delegated) visits by the expected productivity per physician. After the individual Delphi panels provided their "realistic-yet-idealistic"judgments on a morbidity-specific basis, the GMENAC modeling subcommittee made changes to the Delphi estimates where they felt "adjustments to reflect reality" were needed. A relevant case in point is the issue ofvisit delegation to NPPs. When the individual specialty panels completed their idealjudgments regarding the use of NPPs, in aggregate, over twice as many NPPs as forecasted to be available in 1990 (70,000) would be needed. Because of the problems of doubling NPP supply, when a surplus of physicians is projected, the delegation rates were reduced to a level consistent with full utilization of the projected 1990 NPP
The future of nurse practitioners (NPs) and physician assistants (PAs) has never before been confronted with as much uncertainty as in today's rapidly evolving health system.'" There are those who would argue that the role for "physician substitutes" is minimal in an era of increasingly abundant physicians. Alternatively, others suggest that nonphysician providers (NPPs) are entering a potential heyday, as organized and prepaid group practices-which have relied more heavily on NPPs in the past-become a major organizational form of health care delivery. How these and other opposing pressures impact upon NPPs will unfold in the next few years. The purpose of this article is to examine evidence regarding the actual and normative roles of NPPs in three Health Maintenance Organization (HMO) practice settings. The impact of these findings, for future United States NPP and physician requirements will be explored using the modeling framework developed by the Graduate Medical Education National Advisory Committee (GMENAC), which projected 1990 physician requirements and the extent of a physician surplus. Implications of the findings for future roles of NPPs are discussed. The GMENAC was chartered in 1976 by the Secretary of Health, Education, and Welfare and reported its findings in 1980.56 The Committee was charged with developing recommendations regarding future physician requirements for the US. The group generated what many consider to be the most extensive set of models ever developed for the purpose of health manpower forecasting. To calculate the requirement, or need side of the model, GMENAC relied heavily on normative expert judgments derived by expert panels using a Delphi group process. These specialty-specific panels included practicing and academic physicians, with one or two NPs or PAs participating in most groups. In addition, a separate panel was convened to provide overall guidance on issues relating to NPPs.5 From the Health Services Research and Development Center, Johns Hopkins University, School of Hygiene and Public Health. Address reprnt requests to Jonathan P. Weiner, DrPH, Assistant Professor of Health Policy, Health Services Research and Development Center, Department of Health Policy and Management, School of Hygiene and Public Health, Johns Hopkins University, 624 N. Broadway, Room 605, Baltimore, MD 21205. Dr. Williamson is currently Director of the HSR&D Field Program at the VA Medical Center, Salt Lake City, Utah. This paper, submitted to the Journal September 5, 1985, was revised and accepted for publication December 2, 1985. Editor's Note: See also related editorial p 493 this issue. C 1986 American Journal of Public Health 0090-0036/86$1.50
AJPH May 1986, Vol. 76, No. 5
supply. GMENAC forecasted shortages in five relatively small physician specialties, surpluses in most surgical specialties and the medical sub-specialties, and "near balance" in the primary care specialties. Overall, however, the committee portends a surplus of one in every five physicians by the year 2000. The report of GMENAC has generated considerable controversy regarding its implications for the US health care system.7 Probably no group was more concerned than the NP and PA professional societies and training programs. The issue the NPP groups most often cited in criticism of the GMENAC requirements model was the subjectivity of its parameters, especially with regard to delegation. The data reported here derive from a larger study whose purpose was to assess the normative requirement models developed by GMENAC for eight major specialty groups: adult medicine (general internal medicine and family practice), general pediatrics, obstetrics/gynecology, general surgery, orthopedic surgery, dermatology, hematology/oncolo507
WEINER, ET AL.
gy, and gastroentology. GMENAC's methods were evaluated by developing empirical practice data from three HMOs in a format consistent with the original Delphi panel derived data. These data were then used to recalculate GMENAC's requirement model. In addition, for pediatrics, a replication of the national Delphi panel was convened at each HMO to develop local "ideal" judgments similar to those used by GMENAC. Therefore, this study allows for comparisons of models based on three data sources: * GMENAC's normative (Delphi derived) findings and the HMO's empirical (practice derived) findings (for eight
specialties); * GMENAC's normative findings and the HMO's normative findings (for pediatrics); * The HMO's empirical findings and the HMO's normative findings (for pediatrics). The reader is referred elsewhere8'9 for a discussion of the implications of the project for the physician specialties. Only the results that relate to delegation to NPPs will be presented
here. Methods
Study Sites
The three HMOs participating in the study were selected based on considerations of population size, comprehensiveness of care, geographic dispersion, demographic characteristics of enrolled populations, and adequacy of data systems. In selecting the three, an effort was made to identify HMOs that varied in their use of non-physician providers. The study's observations cover a one-year period during 1980 and 1981; characteristics of each study site, at that time, are described briefly. The Harvard Community Health Plan (HCHP) is a staff model HMO with over 100,000 enrollees in the Boston area and few fee-for-service patients. The practice makes extensive use of NPs and PAs with approximately one NPP for each physician. It uses an automated medical record system, known as COSTAR,10 which was the source of data for this study. The MedCenters Health Plan (MCHP) is a group practice HMO with over 100,000 enrollees in the Minneapolis area. The HMO complements a large fee-for-service practice that accounts for approximately the same number of visits as the HMO. Physician payment is related to patient care charges generated, for both enrollees and fee-for-service patients. Some nurse practitioners are employed, with an approximate ratio of one NPP per 9.5 physicians. The source of data for this study came from a management information system that captures data on every visit, including diagnosis and information necessary for billing. Maxicare (MAX) is a network-IPA (independent practice association) HMO with over 100,000 enrollees in the Los Angeles area. One large medical group within the network participated in this study. Similar to MCHP, there is also a substantial fee-for-service practice and physician payment is related to charges generated. NPs were used on a limited basis with one NPP for every 17 physicians. The source of data is a management information system similar to MCHP. At each HMO, a population of approximately 40,000 persons was selected. These individuals represented all persons who were continuously enrolled at the largest practice locations within each plan for at least 18 months. All health care utilization of these 120,000 individuals was empirically observed for the entire period. Each of the HMO sites used a different diagnostic coding system and for two 508
sites, it was necessary to recode diagnoses into ICDA-8 categories consistent with those used by GMENAC. The characteristics of the study populations are similar for the most part. They include relatively few elderly and few poor (Medicaid) or near poor families. Minority representation, including Blacks and Latinos, is limited at HCHP and MCHP but accounts for approximately one-third of the MAX study population. HMO Delphi Panels
At each of the three sites, Delphi panels were constituted from the practicing clinicians in general pediatrics. The individuals selected at each plan represented either the entire pediatric team at the HMO's collaborating practice location, or a sample of practitioners deemed to be representative by the head of the pediatric unit. At HCHP, five pediatricians and three nurse practitioners participated; at MCHP there were four pediatricians, one family physician, and one nurse practitioner; at MAX there were three pediatricians and one family physician. The panels were convened in 1982. Four stages were involved in the modified Delphi process used to develop local standards (defined as "reasonable ideals that would be acceptable as standards of practice"): 1. The first stage involved independent judgments. The panel members received the same material as did the original national Delphi panel. The scope of diagnoses dealt with by the reconvened panel was more limited, however. 2. The second stage involved a meeting to reach group consensus. 3. The third stage involved independent judgments based on the results of the group session and actual empirical practice data derived from their own practices (at the original GMENAC panel, national practice data were made available to panel members). 4. The fourth stage involved a second face-to-face meeting to reach group consensus based on the results at the third (independent) stage. Although the methodology applied during the HMO Delphi process was slightly different from that of GMENAC, the outcome of each HMO panel was believed to represent a normative consensus of the local practitioners in a format comparable to that developed by the national panel of experts. Results For over a hundred morbidities (accounting for at least 50 per cent of each specialty's workload), NPP visit rates were documented at each HMO. The delegation rate was based upon the percentage of all visits to each specialty seen by NPPs. A visit was considered to have been delegated if the HMO's encounter data system identified the NPP as the principal provider. Some visits where the NPP saw the patient first, after which the patient was also seen by an MD, were therefore included in this category. Table 1 presents GMENAC's suggested delegation rates for major selected conditions seen by six specialties along with the observed delegation rates at each HMO. Note that for most conditions, for all specialties, the HCHP rates surpass or equal those of GMENAC's panels. For adult medicine, the delegation at the other two HMOs is lower, although still significant. For OB/GYN, delegation rates of two of the three HMOs (HCHP, MCHP) appear to be equal to, or higher than, GMENAC's. Table 2 shows the percentage of ambulatory visits classified by specialty that were seen by NPPs at each HMO. AJPH May 1986, Vol. 76, No. 5
NON-PHYSICIAN PROVIDERS IN THREE HMOs TABLE 1-GMENAC's Ideal NPP Deleton RatforSelcted Condftons Compared to Oberved Ratee at Three HMO
TABLE 3-4mpact of Actual and kIeal HMO Delegation Rates on GMENAC Physician Requirment Forecaat* HMO "Delphi"
Per Cent of All Ambulatory Visits Seen by NPPs
Actual
Specialty/Condition
GMENAC Delphi Panel
MAX
MCHP
HCHP
25 25 10 30 8 15
2 2 17 15 21 34
3 1 6 17 5 5
39 37 35 76 68 61
28 10 25 43 12 20
0 0 0 0 0 0
1 7 12 10 5 5
10 16 19 34 36 30
48 18 32 21
15 2 27 25
64 26 30 59
43 32 59 77
18 18 18 18
0 0 0 0
0 0 0 0
59 50 60 51
0 0 0 0
0 0 0 0
0 0 0 0
25 3 100 66
0 0 0 0
0 0 0 0
0 0 0 0
25 19 25 77
Adult Medicine Hypertension Diabetes Asthma URI UTI Well Care General Pediatrics Asthma Pneumonia Otitis URI UTI Well Care OB/GYN UTI Menstrual Disorders Pro-Post Natal Family Planning Dermatology Dermatophytosis Benign Neoplasms Exczema Acne General Surgery* Skin Neoplasms Gallbladder Disease
Sprains Contusions Orthopedic Surgery* Osteoarthritis Back Problems Fracture of Clavicle Fracture of Arm
*GMENAC did not develop explicit delegation rates for these specialties. NPP = Non-physician provider. URI = Upper respiratory infection. UTI = Urinary tract Infection.
TABLE 2-Comparlson of Oveall Ambulatory WsI tIon Rae at Three HMOs wlth GMENAC's Rate by Specialty
Per Cent of All Visits Delegated to NPP
Normative*
Specialty Adult Medicine General Pediatrics OB/GYN Dermatology General Surgery"
Orthopedic Surgery"
Empirical
GMENAC Delphi "Idealistic"
GMENAC Adjusted "Realistic"
22 27 43 23 0 0
12 15 18 18
0 0
MAX
MCHP
HCHP
15 0 21 0 0 0
6 7 41 0 0 0
47 26 56 60 49 44
*Idealistic normative rates were developed by Delphi paneIs on a morbidity spocific basis. Realistic rates developed by "modeling" panel on overall, non-morbidity basis. **No explicit rates were developed by GMENAC for these specalties.
For comparison, the two sets of ideal delegation rates developed by GMENAC are listed. The first normative GMENAC figure represents the "ideal" rate reached by consensus of the expert Delphi panels. The second rate was the one eventually adopted by GMENAC to account for the AJPH May 1986, Vol. 76, No. 5
Specialty (# Physkicans) Adult Medicine (147,067) General Pediatrics (29,974)
Panel
GMENAC Delphi Panel MAX MCHP HCHP MAX MCHP HCHP 100
126
133
73
-
-
-
100
137
125
104
76
73
55
*Al figures rpsent esimats of 190 physan requirements expressed in terms of the per cent of GMENAC's original estimates. Each estimate is based on a model that uses all of GMENAC's orIginal Delphi-based parameters, except the NPP delegation rate, which is derIved from the HMO as indicated.
fact that there would not be enough NPPs available in 1990 to meet the panels' initially suggested delegation rates. The Table indicates that for all specialties the ideal GMENAC rates are achievable as evidenced by the practices at one or more HMOs. However, the actual patterns at the different plans are far from universal; only for one specialtyOB/GYN-did the delegation rate at all three facilities equal or exceed GMENAC's "realistic rate". It is interesting to note that for the two surgical specialties, about half of all ambulatory visits were delegated at HCHP (many to surgically oriented PAs), although GMENAC's original panels did not explicitly incorporate any delegation rates into its model of surgical manpower requirements (although they may have done so implicitly). To assess the implications of the empirically observed NPP visit rates on national physician requirements, a sensitivity analysis was performed. This analysis incorporated the HMO delegation rates into GMENAC's requirement model for the two major primary care specialties. In other words, the original parameters used to derive the GMENAC model were left intact, excepting the delegation rates, where HMO figures were used rather than those developed by the national expert panel. In Table 3, a comparison is presented between the national 1990 physician (MD/DO) requirements for adult medicine and general pediatrics based on the HMO's actual delegation rates and GMENAC's delegation rates. For example, if one assumes Maxicare's overall adult medicine delegation rate (15 per cent) rather than GMENAC's ideal Delphi panel rate (22 per cent), the resulting 1990 MD/DO requirement would be 126 per cent of the number of physicians originally arrived upon using the Delphi panel's rates (i.e., 185,304 MD/DOs vs 147,067). For adult medicine, if two ofthe HMO's delegation rates were adopted as standards, the number of physicians needed would surpass the number arrived upon using the original normative rates. For pediatrics, the actual delegation rates at all three HMOs would lead to a higher MD/DO requirement than the national ideals. Note that this Table compares the HMO rate to the GMENAC's Delphi panel rates; it was not possible to develop a detailed comparison with the "adjusted" delegation rate model (i.e., after the rates were lowered). However, when the actual HMO-based model is compared to the adjusted GMENAC model, a higher adult medicine MD/DO requirement than GMENAC is suggested in one out of three HMOs and a higher pediatric MD/DO requirement in two out of three. The pediatric Delphi panels convened at each HMO allowed for an assessment of the differences between actual 509
WEINER, ET AL. TABLE 4-Comparison of Ideal vs Actual NPP Dehgation Rats for Pediatric Ambulatory Viits Ideal*
US Approximate 1985*** GMENAC Delphi ("Idealistic") GMENAC Adjusted ("Realistic") HMOs MAX MCHP HCHP
-
Actual*" 8
27 15
39 43 61
0 7 26
*Ideal rates determined by Delphi panels (per cent of visits seen by NPPs). "*Determined at HMOs by empirical observation of pracfice (per cent of visits seen by NPPs). ***Based on current supply and productivity of pediatric NPPs and physicians. This figure represents the estfmated percentage of all current pediatric ambulatory encounters that are provided by NPPs.
practices and the "reasonable ideals" (i.e., standards by which the providers in each HMO would be willing to abide). Morbidity specific delegation rates were developed by the physician-dominated panels. With few exceptions, the rates suggested by these groups were consistently higher than the ideal rates suggested by GMENAC's national experts. It is interesting to note that even after the HMO panels were exposed to data on their actual (far more limited) delegation rates, they did not substantially lower their "ideal" rates. Table 4 compares the GMENAC and current US total delegation rates to both the HMO ideal (Delphi) and actual rate. Note that for each HMO, the locally developed ideal rates are far higher than either their own experience or the national standards. The HMO Delphi delegation rates are proportionally higher, where the actual rates are higher. However, even at MAX, with a 0 per cent pediatric delegation rate, an all MD panel suggested an ideal NPP use rate of 39 per cent. To assess the potential effect on GMENAC's original normative-based pediatrician requirement, a sensitivity analysis was performed where the HMO-Delphi delegation rates were input into the model. The far right column, lower row in Table 3 presents the percentage of GMENAC's original MD/DO requirement that would be "needed" if the HMO ideal rates were accepted for pediatrics. In all three cases, accepting the HMO ideal rates would lead to a physician requirement far lower than adopted by GMENAC. Discussion The research sites were selected, in part, because they represent three different types of HMOs (staff, group, and IPA/network), and they have taken different approaches to manpower staffing. The results of this study are not necessarily generalizable to the more than 300 HMOs and other alternative health plans in the nation. However, because of the wide range of delegation observed in the three study HMOs, the practices of most organized settings are quite likely to fall within this range. Although the use of NPPs varies considerably across the three HMOs, it is evident that the delegation rates suggested by GMENAC's experts are clinically feasible. For each specialty, at least one HMO makes use of NPPs at a rate equal to or surpassing the normative. On the other hand, for the two major primary care specialties, the actual NPP use rates at two of the three HMOs are lower than suggested by GMENAC and, if adopted nationally, would necessitate a 510
significant increase in GMENAC's physician requirement forecast to compensate for this lower use. A second notable finding of this study is the substantial difference between the actual use of NPPs at each site and the self-determined ideal standards of providers at that site. While the actual pediatric NPP delegation rates ranged from 0 to 26 per cent, the normative rates ranged from 39 to 61 per cent. This difference suggests the degree to which higher delegation rates are possible at least from the perspective of these three groups of practicing pediatric clinicians. Although the providers at the HMOs did not suggest rates approaching the 90 per cent pediatric NPP substitution suggested by Record and others," it is clear that considerable expansion past GMENAC's moderate standards would be acceptable to these groups of practicing physicians, two of which had only limited exposure to NPPs. Before discussing the implications ofthis study for future NPP and MD/DO requirements, it would be appropriate to briefly review the history and mission of the NP and PA professions. Both types of practitioners owe their genesis to the initiatives of the federal government, and others, to improve the care received by many Americans during the 1960s.t2 This perceived inadequacy was due, in part, to a physician shortage at that time. With heavy reliance on government training subsidies, NPs and PAs were expected to improve access to care in rural and inner-city areas, increase the availability of primary care in all areas, produce a health provider team that would be more cost effective than the solo physician, and improve quality of care by augmenting and enhancing the roles of physicians. While still the subject of some debate, the measurable evidence is fairly supportive of the NPPs. As of 1985, there were approximately 26,000 NPs (including midwives) and approximately 19,000 PAs.'3 Moreover, the nation's 208 NP programs and 54 PA programs are turning out annual cohorts of approximately 2,500 and 1,500 respectively. As promised, they have entered the primary care specialties-90 per cent of all NPs and 75 per cent of all PAs-and they are accepted as providing care of high quality. 13"14 While they have located themselves in rural and inner-city areas at a rate somewhat higher than physicians, only a small percentage of NPPs practice in underserved areas. The cost-effectiveness of NPP-MD teams over MDs alone has been supported by research; however, these findings are not without caveats. Some studies have shown only a modest cost savings due to the considerable difference between the productivity rate of NPPs and MDs (MDs see almost twice as many patients per hour). In addition, some concerns have been expressed that actual cost savings experienced by NPP-MD delivered care, may not always be passed through to patients and payers, particularly when services are delivered on a fee-for-service basis. Evidenced in several studies is the fact that cost-savings to patients are highest in prepaid organizations, where strong incentives exist to substitute lower priced practitioners where possi-
ble.'4
Most support for the NPP movement has been garnered
during an era of physician shortage, during which all medical manpower training programs (including NPPs) received heavy subsidies. As recently as 1984, about half of all NPP programs received substantial federal capitation payments which, in total, was equivalent to more than $4,000 per student per year for the entire NPP graduating class (including all programs).'3 It is unlikely that such government support will continue. AJPH May 1986, Vol. 76, No. 5
NON-PHYSICIAN PROVIDERS IN THREE HMOs
As the increasing physician supply leads to a diffusion of practitioners into previously underserved areas, this may undercut the need for NPPs. On the other hand, it is doubtful whether the least desirable regions of the US will ever attract an adequate complement of physicians. From the results of this study, it is clear that a very significant percentage of the needs in these areas could be delegated to NPPs. The pressures to hire NPPs as physician "substitutes" is likely to decrease, especially given that MDs are capable of treating a wider scope of patients and conditions in a more independent manner. The issue of quality of care, however, remains a difficult and controversial one. Some evidence has been developed to suggest that rather than mere "substitutes", NPPs can deliver some types of care (e.g., preventive care) better than physicians alone.'4 The professed cost-effectiveness goal of the NPP movement was usually placed "last on the list" in the access conscious era of the 1960s and 1970s. In today's costcontainment era, however, the cost efficiency of NPPs is likely to be critical. To the extent that care delivered with NPPs is more efficient than care given without NPPs, demand for NPPs would be expected to increase. The fact that large numbers of NPPs are employed by group practices and HMOs paid under capitation arrangements lends support to this argument. In the future, a favorable cost-effect ratio could be altered by further differences in NPP-MD productivity and the possibility that market forces may drive up the NPP salary, or lower that of physicians. Moreover, the inclusion of quality adjustments could potentially affect this ratio either to the detriment or advantage of the NPP professions. From this and other studies, it is evident that organized practices can rely on NPPs to provide very significant amounts of care. In these settings, NPPs are involved in the treatment of a variety of conditions in both primary and specialty care. If the growth of HMOs and other alternative plans continues, if cost pressures do lead to an increased desire to substitute NPPs for physicians, and if an increased supply of NPPs could be rapidly trained to meet this demand, then, the MD "surplus" would probably surpass even GMENAC's forecast. However, even assuming that an adequate supply of NPPs could be produced in the absence of federal subsidies, this study suggests that this scenario is far from certain. Two of the three observed HMOs, both successful in highly competitive environments (Minneapolis and Los Angeles), made only limited use of NPPs. The reasons for this are not clear, especially since a representative group of practitioners at those sites indicated that they would accept a significant increase in NPP use. If such organizational reticence to incorporate NPPs becomes commonplace among the expanding health plans, an increased role for NPPs would seem unlikely. It is even possible that such trends could lead to a physician surplus less severe than
AJPH May 1986, Vol. 76, No. 5
expected by GMENAC in order to compensate for a lower than anticipated use of NPPs. Whether or not the health care organizations created by the 1980s expand or contract their reliance on the practitioners created by the 1960s, will soon become evident. ACKNOWLEDGMENTS
The cooperation of the three collaborating HMOs is gratefully acknowledged. Dan Ershoff, DrPH, at Maxicare; J. Paul O'Connor, Paul Batalden, MD, and Jackie Vos at the MedCenters Health Plan; Kathryn Coltin and Dan Geer at the Harvard Community Health Plan; and Jerald Katzoff at the USDHHS, Bureau of Health Professions (Division of Medicine) assisted in various phases of the project. Sam Shapiro, David Levine, MD, Barbara Starfield, MD, Maureen Fahey, and Charlotte Gomez, from the JHU Health Services Research and Development Center, were also members of the research team. The involvement of the pediatric clinicians at the HMOs participating in the Delphi panels is also acknowledged. This work was supported in part under contract HRA-232-81-0035 with the Bureau of Health Professions, USDHHS. The opinions expressed herein are those of the authors and should not be construed as representing the policy of the USDHHS. An earlier version of this paper was presented at the 111th annual meeting of the American Public Health Association, in Dalias, Texas, November 1983.
REFERENCES
1. Spitzer WO: The nurse practitioner revisited: slow death of a good idea. N Engl J Med 1984; 310:1049-1051. 2. Cawley JF, Golden AS: Non-physicians in the US: manpower policy in primary care. J Public Health Policy 1982; 4:69-82. 3. Cawley JF: The physician assistant profession: current status and future trends. J Public Health Policy 1985; 6:78-99. 4. Ford LC: Nurse practitioners: history of a new idea and predictions for the future, In: Aiken L (ed): Nursing in the 1980s. Philadelphia: J.B. Lippincott, 1982. 5. GMENAC (1980): The report of the graduate medical education national advisory committee. Vols I-VII. USDHHS, Pub Nos. (HRA) 81-651 to 81-657. Washington, DC: Govt Printing Office, 1980. 6. McNutt D: GMENAC. Its manpower forecasting framework. Am J Public Health 1981; 71:1116-1124. 7. Bowman M, Walsh W: Perspectives on the GMENAC report. Health Affairs 1982; 1:55-66. 8. Steinwachs DM, Shapiro S, Weiner JP: An Application of the GMENAC physician requirement model to empirical data derived from three HMOs. USDHHS Contract (HRA-232-81-0035), Johns Hopkins University, Health Services Research and Development Center 1983. (Available from NTIS, No. HRP.0905883.) 9. Steinwachs DM, Weiner JP, Shapiro S, et al: A comparison of the requirements for primary care physicians in HMOs with projections made by the Graduate Medical Education National Advisory Committee. N Engl J Med 1986; 314:217-22. 10. Barnett 0: Computer-stored ambulatory record (COSTAR). US Dept of Health, Education, and Welfare. Pub. No. (HRA)76-3145. Washington, DC: Govt Printing Office, 1976. 11. Record JC, McCally M, Schweitzer SO, Blomquist RM, Berger BD: New health professionals after a decade and a half: delegation, productivity and costs in primary care. J Health Politics, Policy and Law 1980; 5:470-497. 12. Yankauer A, Sullivan J: The new health professionals: three examples. Ann Rev Public Health 1982; 3:249-276. 13. USDHHS, Bureau of Health Professions: Report to the President and Congress on the Status of Health Personnel in the US, 1984. USDHHS Pub. No. HRS-P-OD 84-4. Washington, DC: Govt Printing Office, 1984. 14. LeRoy L: The Costs and Effectiveness of Nurse Practitioners. US Congress, Office of Technology Assessment July 1981; Case Study #16. Washington, DC: OTA, 1981.
511
