This Article
* Abstract
* Submit a response to this article
Services
* E-mail this article to a friend
* Alert me to new issues of the journal
Weiner Web Exclusive


W O R K F O R C E P O L I C Y :
P G P S T A F F I N G
W E B E X C L U S I V E
4 February 2004 Prepaid Group Practice Staffing
And U.S. Physician Supply:
Lessons For Workforce Policy

What can we learn from examining the staffing levels of some
of the country’s largest organized delivery systems?


By
Jonathan P. Weiner



ABSTRACT:

This paper describes staffing at eight large prepaid group practices (PGPs) serving more than eight million enrollees at Kaiser Permanente and two other health maintenance organizations (HMOs). Even after characteristics of the patient populations and outside referrals are accounted for, these PGPs have a physician-to-population ratio that is 22–37 percent below the national rate. Two decades of historical data at Kaiser Permanente indicate that its rate of specialist growth was far higher than that of primary care. The study suggests that efficient systems of care can readily meet the demands of patient populations with workforce staffing ratios below current U.S. levels.


Prepaid group practices (PGPs) are highly structured, multispecialty medical groups that are reimbursed by capitation to serve the enrollees of a health maintenance organization (HMO). When PGPs were founded in the mid-twentieth century, the strategies they adopted were unique. They emphasized primary, preventive, and ambulatory care and were among the first to welcome nonphysician providers (NPPs) such as nurse practitioners (NPs) and physician assistants (PAs). PGPs were also among the first to develop coordinated approaches to care delivery. Many of these innovations have been disseminated widely within the U.S. health care system. Other staffing and organizational approaches used by PGPs still set them apart from the less structured fee-for-service (FFS)–oriented U.S. health care system.

Even though PGPs are a relatively small segment of U.S. practice, managers and policymakers have looked to them since their inception as an example of how best to “staff up” to provide care for defined populations. Within the disaggregated U.S. health care system, there are few other instances where a “numerator” of providers and a “denominator” of consumers/patients are so clearly demarcated.

Over the past four decades, policymakers, labor planners, and clinic managers have used staffing ratios derived from PGPs to help determine whether the supply of providers in a particular geographic area or within a particular care delivery organization is “adequate.”1 In addition, national and regional workforce planners have assessed the potential impact of PGPs as they, and other organizations patterned to some degree after them (such as independent practice association, or IPA/network-model HMOs), have become more widespread. Specifically, in the late 1980s and early 1990s, when national health reform based on competitive integrated delivery systems was being seriously considered, there was intense interest in staff/group-model HMOs as one prototype.2

Although such government-led reformation did not come to pass, other changes did occur: Corporate-controlled “managed care” became ubiquitous. But after a decade of mainly for-profit, loosely organized plans in the mainstream, a widespread “backlash” ensued, leading to the current environment in which policymakers, consumers, and clinicians are seeking alternatives to managed care. PGPs, with their unique roots in both the social welfare and cost containment movements, represent one such alternative.

In this paper I provide a detailed case study describing how eight large PGPs have structured their workforces to deliver care to consumers enrolled in Kaiser Permanente (KP) and two other HMOs: the Group Health Cooperative (GHC) of Puget Sound in Seattle, and HealthPartners (HP) in the Minnesota Twin Cities. This study documents staffing for six distinct regions of the Permanente Medical Group. The focus of this paper is allopathic (MD) and osteopathic (DO) physicians. Also included are PAs, NPs, and other nurse specialists (such as midwives and nurse anesthetists) who can be viewed to some extent as physician substitutes. The paper also documents the PGPs’ employment of certain non-MD/DO doctors (such as optometrists, psychologists, and podiatrists) and independent mental health therapists.

One objective is to identify the unique approaches that each PGP has chosen to meet the needs/demands of its patient population. To allow readers to assess how the PGPs compare with current U.S. patterns of practice, throughout the paper comparisons are made with current U.S. medical workforce supply ratios. The paper greatly expands upon previous work in this area. In addition to collating recent data, it provides detailed information for ambulatory and hospital-based physician specialties, out-of-group contracted care, and NPPs.

Study Sites And Methods

The PGP providers documented in this study practice at more than 350 clinic sites and 33 hospitals owned and staffed by HMOs. The PGPs serve a population of more than eight million consumers residing in nine states and the District of Columbia. The KP enrollees represent about 93 percent of this total; the two California regions (Northern and Southern California), about 75 percent. Combined, the California PGPs serve more than six million enrollees who obtain care from more than 140 ambulatory sites and 28 fully staffed inpatient facilities. No other private medical group (prepaid or otherwise) approaches this size and level of comprehensiveness. The GHC and HP organizations also own and staff their own hospitals; however, they make greater use of nonemployed contracting physicians to serve the medical needs of their members than the KP sites do. All PGPs in this study provide most mental health services on site and do not contract with a “carve-out” behavioral health plan.

Two of KP’s eight regions (Ohio and Georgia), accounting for about 8 percent of KP’s national enrollment, were excluded from this study. A sizable proportion of the services there were provided by physicians who were not part of a Permanente Medical Group, and the data describing out-of-plan contracting were less complete than desired for this study. For similar reasons, only the western Washington region of GHC was included, excluding eastern Washington and Idaho.

The patient populations included in this analysis represented only those enrollees who were registered with primary care sites staffed by the PGP. Enrollees served by the plans’ independent physician networks were not included. For KP and GHC, the percentage of enrollees thus excluded was fairly modest (less than 10 percent); however, about half of all HP enrollees are served by contracting group practices across the region. Plans provided the information used in this analysis during mid-2002 for a reporting period of late 2001 or early 2002.

Relevant characteristics of the practices, by study site, are shown in Exhibit 1, which also presents estimates of the percentage of all hospitalizations provided in HMO-owned hospitals and the proportion of covered physician services that are delivered by providers not employed by the health plan’s collaborating PGP.

Exhibit 1.

View larger version

[in this window]
[in a new window]

 

 

 



Study Results

Exhibit 2 presents a comprehensive specialty-specific description of the PGP-employed physicians in more than forty specialties.3 The rates are expressed in terms of employed full-time-equivalent (FTE) patient care MDs and DOs on the staff per 100,000 people enrolled at each site.

Exhibit 2.

View larger version

[in this window]
[in a new window]



 

 


To enable a comparison with the current overall U.S. medical workforce, the most recent data on the availability and characteristics of physicians were obtained from American Medical Association (AMA) and American Osteopathic Association (AOA) “masterfile” sources. For comparability, all “U.S. supply” rates presented in this paper include only nonfederal, nontrainee providers who are actively involved in patient care. Thus, about 18 percent of the current active (non-retired) U.S. physician supply—which equals approximately 280 MDs/DOs per 100,000—is excluded from the comparison. Although this approach is standard among workforce analyses, it conservatively underestimates the true availability of clinically active providers in the United States.

Physicians employed by the group provide the majority of care at each PGP. However, for sites other than the two extremely large California KP sites, the staffing rates for the tertiary and hospital-based specialties documented in Exhibit 2 (and in an expanded Exhibit 2 online; see Note 3) are likely to be incomplete. At the other sites, nonemployed contracting physicians provide many specialized services; I return to this point later.

At some PGPs, medical directors and other administrative physicians who are actively involved in managing care are reported within their respective medical specialties. Others include these physicians in a separate “medical director” category. The proportion of employed physician time spent on nonclinical activities (such as research) was excluded from the reported staffing rates at all sites.

Exhibit 3 presents a breakdown of NPs/PAs and other NPPs who deliver services that in other settings are typically delivered by physicians. Some of the sites (notably GHC and several KP sites) made considerable use of nurses (generally registered nurses without NP training) to staff round-the-clock triage “call centers.” Although this is an innovative use of clinicians, these nurses, along with other ambulatory care nurses such as clinic nurses or case managers, and other inpatient nurses were excluded from this physician services–oriented analysis.

Exhibit 3.

View larger version

[in this window]
[in a new window]










Exhibit 4 provides a site-specific summary of the rate of overall employed providers, including both MDs/DOs and NPs/PAs before any adjustments are applied. The physician figures are broken down by primary care and specialty care.

Exhibit 4.

View larger version

[in this window]
[in a new window]










Before we attempt to use these PGP staffing rates as a benchmark for other populations, a series of adjustments must be made.4 These include adjustments for difference between the demographics of HMO enrollees and the U.S. population; the extent to which nonemployed physicians provide covered care; and the proportion of providers’ time spent on patients who are not enrolled with the PGP.

Exhibit 5 offers estimates of these three sets of adjustment factors for each PGP. (Non-California KP sites are combined as “other.”) All of the factors noted in this exhibit are multiplicative, which means that they should be multiplied by the employed provider rates in previous exhibits to account for each factor noted.

Exhibit 5.

View larger version

[in this window]
[in a new window]










The first row of Exhibit 5 presents an approximate demographic adjustment. This is based on a comparison of the demographic characteristics of each PGP’s enrollees with the characteristics of the U.S. population as of 2000. An indirect standardization method was applied using age- and sex-specific ambulatory physician contacts derived from a national HMO survey.5 All three PGPs have a significantly higher proportion of elderly enrollees than the U.S. HMO average and thus have age distributions similar to that of the U.S. population. Therefore, little adjustment of the reported staffing rates is needed to account for demographic mix.

Even though the PGPs in this study are among the largest in the country, community-based physicians not employed by the plan deliver some members’ care. Outside providers are reimbursed primarily by FFS. Two of the sites (GHC and HP) could share specialty-specific information of this type. Using a method developed at GHC, national group practice annual billing averages by specialty were used to estimate the FTE rates (in terms of physicians per 100,000 members) of the outside services provided by contracting physicians.6 KP, which makes less use of such physicians, provided estimates based on historical experience.

Exhibit 5 presents “external contract provider” adjustment factors by major specialty group. These factors, like the others in the exhibit, are multiplicative. For example, overall at GHC, 87 percent of the care is provided by the PGP’s employed providers and the remaining 13 percent by community doctors. Therefore, an adjustment factor of 1.15 should be multiplied by the employed staff rates presented previously, to approximate the total number of FTEs serving the HMO enrollees.

All of the PGPs in this study primarily serve the members of their affiliated HMOs. They are paid a capitated fee for these services. But in certain circumstances, the PGP providers care for patients from outside the enrollee denominators described in Exhibit 1. This might include emergency care to nonmembers; “reciprocal” coverage for members of another HMO; services to members of the PGP’s partner HMO enrolled with an external IPA; or care for members insured under a separate policy (such as workers’ compensation). The “nonenrollee care” adjustment factors, based on actual recent history at each site, are presented in the last row of Exhibit 5. They indicate the approximate downward adjustment of employed FTEs that is necessary before they can serve as external benchmarks.

Exhibit 6 provides an overview of “adjusted” provider supply at the PGPs after applying the three sets of factors described in Exhibit 5. U.S. rates are also presented as a point of reference. Exhibit 6 provides estimates of physician supply per 100,000 enrollees after the “outflow” (that is, enrollees leaving the group for care) and “inflow” (that is, nonenrollees getting care from group providers) are taken into account. These figures represent this paper’s “bottom line” in terms of how the overall provider staffing in PGPs compares with the current U.S. provider supply, once all adjustments are taken into account.

Exhibit 6.

View larger version

[in this window]
[in a new window]










An analysis similar to this one was published in 1989, using 1983 KP data. Using these data, with augmentations from other sources for NPPs, it was possible to do an eighteen-year trend analysis at KP. These 1983–2001 trends are then compared with the underlying U.S. supply trends over approximately the same time period (1980–2000). Exhibit 7 presents these two sets of figures by specialty class and separately for physicians, NPPs, and both combined. The KP data in this exhibit have not been adjusted; they reflect employed FTEs. To account for the slightly different number of years included in the two data sets, annualized trends are presented in the rightmost column.


Exhibit 7.

View larger version

[in this window]
[in a new window]









Discussion And Policy Implications


Summary of findings. Across the PGPs, overall adjusted physician staffing ranges from about 144 to 176 per 100,000 enrollees, compared with a national ratio of about 229 per 100,000.7 When both physicians and NPPs are combined, the overall adjusted supply ranges from about 174 to 202, compared with about 270 per 100,000 nationally. This is equivalent to about 1 provider for every 490 enrolled people at GHC, 1 per 495 at HP, and 1 per 575 at KP. The nation’s overall (nontrainee, nonfederal) provider-to-patient ratio is about 1 per 370.

Staffing levels at the three PGPs (and the six KP regions) fall within a fairly tight range. But beyond this aggregate level, a number of interesting variations are noteworthy and show the alternative approaches these organizations have taken to meet the needs of their populations.

The proportion of primary care physicians at each site ranges from about 40 percent to 46 percent after adjustments are made for contracting providers. This compares with about 41 percent of primary care MDs/DOs nationally. Percentages may be misleading, however; the U.S. primary care physician supply is about 93 per 100,000, whereas the adjusted primary care supply in the PGPs ranges from 58 to 80 per 100,000. At HP, 10 percent of primary care providers are NPs or PAs; at KP the non-MD/DO proportion is 17 percent, and at GHC it is 25 percent. Nationally, about 14 percent of primary care providers are nonphysicians.

NP/PA staffing, in total, ranges across the PGPs from about 26 to 38 per 100,000 (compared with approximately 41 per 100,000 nationally). It appears that the practices of PAs and NP/APNs (which for this analysis include midwives and nurse anesthetists) are concentrated in the specialty care areas at HP and KP (65 percent and 60 percent, respectively). In contrast, the NPP focus at GHC is predominantly (60 percent) primary care. When other types of NPPs (beyond NPs and PAs) are taken into consideration, the deployment across the three PGPs is fairly similar, in the range of 48–53 providers per 100,000 enrollees. No comparable national rates are readily available for this expanded NPP definition.

The eighteen-year KP trend analysis suggests that its rate of annual growth in the overall physician-to-population ratio (1.4 percent) is not too dissimilar from the national increase of 1.7 percent during roughly the same period. However, this trend obscures a noteworthy finding. Most of KP’s growth has been among non– primary care physicians; there was a 2.4 percent annual increase in specialists at KP and only a 0.3 percent annual increase in primary care physicians. This compares with 1.2 percent for specialists and 2.4 percent for primary care nationally.

For nonphysicians at KP, the specialist-oriented trend was even more pronounced; specialty care NPs/PAs grew 6.9 percent annually, but there was zero growth for primary care NPs/PAs. This lopsided situation mirrors the national picture: Specialty care NPPs grew 13.6 percent annually, compared with a 1.8 percent annual increase in primary care NPPs.

Limitations and generalizability. The PGP workforce statistics presented in this paper are arguably the most comprehensive and accurate of this type ever compiled, and certainly the most up-to-date available in the public domain. However, a number of limitations should be noted, particularly as they relate to the generalizability of these workforce levels beyond the PGP setting. When collating data from the multiple practice sites, I used common definitions and data collection frameworks whenever feasible. But, of necessity, there was considerable reliance on local definitions and existing management databases at the PGPs.

When one is considering the implications of the staffing patterns reported in this paper, it is important to acknowledge the context from which they were drawn. That is, the physician and NPP rates must be understood from within the framework of the overall organization, its administrative support staff, and its philosophies. While many aspects of the PGPs’ practices—including approaches to medical staffing—can be emulated in non-PGP settings, in certain instances it may be difficult to adopt just part of the “package.”

Although the PGPs studied here provide care to a broad cross-section of members, their enrolled populations are not representative of all Americans. In addition to the empirical adjustments described previously, a series of other comparability issues has been recommended for consideration before PGP staffing ratios such as those presented here are extrapolated to other organizations or locales.

One issue that must be considered for national planning purposes is the degree to which people enrolled in HMOs choose to get care on their own outside of the plan (from neither PGP-employed nor contracting providers). Because services at these PGPs are so comprehensive, this external use rate is not expected to be very high (estimates have suggested that it is less than 5 percent).8

Another interesting issue, and one that is difficult to measure, is the degree to which PGPs experience “adverse” or “positive” selection bias. That is, are their enrollees sicker or healthier than non-PGP patients, and could they be expected to require more or less care? The national studies on this issue are mixed, but those emphasizing PGPs (rather than HMOs more generically) have suggested that PGP-model HMO populations are not healthier than community-based patients.9 Adding to this national observation was a local analysis at HP suggesting that the morbidity burden (based on the ambulatory care group, or ACG, case-mix measure) among the PGP patient cohort was approximately 10 percent greater than for people in the HMO’s IPA network.

Another issue of comparability relates to potential need for “socioeconomic” adjustments. These PGPs have Medicaid memberships that range from 0.7 percent to 13 percent of their populations, and they have no uninsured patients. This compares with 11 percent and 13 percent, respectively, for these special-need population cohorts within the larger U.S. population. The evidence is mixed on whether an upward or downward adjustment would be needed if the PGP patient populations included a proportional representation of these special-need patients.10

The issue of geographic distribution also deserves comment. The PGPs in this study serve consumers in nine states and the District of Columbia. However, they are based primarily in the West and Midwest and do not have much presence in rural areas. Practice patterns in the study locales could be different than in the United States overall, although there is no evidence that the medical needs of the populations in the underrepresented geographic areas would be higher or lower than those of consumers in the study PGPs.

As much a conceptual issue as one of PGP/non-PGP comparability is the complicated and controversial issue of how to define provider “productivity” and “full-time equivalency”: Does one FTE physician at the PGP equal one FTE outside of the PGP? Further adding to the controversial nature of this discussion is its relationship to the provider’s sex.

AMA surveys and other sources have documented differences in terms of number of patients seen per year by “private practice” physicians compared with PGP-employed physicians. FFS doctors, on average, see 15–20 percent more patients annually than those in more structured settings such as PGPs.11 Therefore, some have suggested that it takes fewer FFS physicians to provide comparable amounts of care. These surveys do not attempt to assess comparability or efficiency associated with patient-physician interactions, simply the number of hours per year spent seeing patients in different settings.

Another related issue is the number of people it takes to constitute one FTE. Because of the structure of PGPs, it is believed that a sizable proportion of physicians work part time in such settings. For example, KP Northern California reports that 20 percent of all permanent physicians on staff work less than 90 percent of what the organization considers to be a full-time schedule. Although comparable national data are not available, based on a 2000 national survey, the AMA reports that only about 10 percent of physicians worked fewer than twenty hours per week or described themselves as not fully active.

There has been a documented tendency for female physicians to work fewer hours per year than their male counterparts. This has been cited by some analysts as being an important factor in understanding national supply and requirement patterns as more women enter the medical profession.12 Numbers of male and female physicians at KP who practice part time are not available, but medical managers at the plan believe that more women than men work part time.

PGPs appear to be appealing to female physicians, likely because of the supportive and flexible nature of their practice environment. Although only 22 percent of U.S. physicians (post-training) are female, 31–47 percent of physicians across the six KP sites in this study were female. This rate is quite similar to where the United States is expected to be in a decade or two.

The net result of part-time status issues is that each FTE reported here represents more than a single person: It can be estimated that every 1.00 reported FTEs reflects 1.10 to 1.20 employed practitioners. Nationally, the comparable rate falls in an estimated range of 1.05–1.10. The full-time equivalency and PGP versus non-PGP productivity issues should be the subject of further inquiry.

Implications for workforce policy. This paper presents workforce supply ratios for large populations served by several very large “closed” integrated delivery systems (IDSs). These staffing ratios are likely to have direct implications for human resource planners in other large IDSs as they seek benchmarks for “staffing up” to meet the needs of their consumer/patients. These other structured systems include not only PGPs but also well-integrated physician-hospital organizations, large non-PGPs with geographically defined patient bases, government providers such as the military, and the structured delivery systems found in other countries.13

What are the implications of the provider staffing rates described here, beyond other structured practice settings? Are PGPs’ workforce levels appropriate benchmarks for the majority of Americans who do not receive care from PGPs or other organized delivery systems?

Determining whether a given provider-to-patient ratio is too low, too high, or just about right is both technically and conceptually difficult. Over the years, alternative methodological approaches have been used to set medical workforce “requirement” benchmarks. The approaches have generally embraced one of three theoretical frameworks: economic demand, clinical need, or HMO staffing. The latter approach has been a relatively common method for setting workforce adequacy reference points because of its intuitive appeal and its relatively modest data requirements.

I did not set out to review the advantages and disadvantages of the alternative methodologies used to set workforce availability standards. Nor did I set out to apply the PGP staffing data in this paper to evaluate the adequacy of the current or projected U.S. physician supply. Rather, in terms of policy impact, my intent was to offer fresh information to support the formal workforce planning activities now under way within both the public and private sectors (for example, the federally sponsored Council on Graduate Medical Education, or COGME, and the efforts of the Association of American Medical Colleges, or AAMC).

This study provides evidence that organized PGPs in urban and suburban areas provide high-quality, cost-effective care to a diverse insured population with considerably fewer physicians than are now available in the nation at large. After adjustments are made to take differences in U.S.-to-PGP enrollee demographics and use of providers not employed by the PGP into consideration, the physician-to-population ratios at the three PGPs is approximately 22–37 percent lower than the overall U.S. ratio. When NPs and PAs are added to the mix, the PGPs’ total provider supply rate is about 24–36 percent lower than the national rate.
When the U.S./PGP provider supply differences are assessed separately for primary and specialty care, an interesting situation comes to light. Two PGPs’ primary care provider staffing levels are closer to the national average than their specialty care rates are. At GHC and HP, the primary care provider rate is 15–18 percent lower than the national rate; their specialty rate is about 30 percent lower. At KP, both the primary and specialty care supplies are about 35 percent lower than the national supply. One issue that may affect the comparability of PGP and U.S. practice is worth noting here. At the well-organized PGPs, it is likely that internal medicine subspecialists (and certain other non–primary care physicians) are serving as true referral specialists, while in FFS practice, a mix of specialty and general care is not uncommon for these providers.

Starting from a base of about half of all providers in the primary care specialties, the trend analysis at KP suggests that this organization (and potentially other PGPs) has been playing catch-up with regard to national specialist staffing. Ironically, this PGP specialist growth seems to have occurred at roughly the same time the national supply of generalists has approached the relatively high proportion seen within PGPs a few decades earlier. While the causes and consequences of these obverse trends are not entirely clear, they do lend support to the premise that the nation must carefully reassess the appropriate balance between primary and specialty care.

Over the past few years, interest in assessing the “adequacy” of the U.S. medical workforce has increased dramatically. Key parties are calling for a reappraisal of our current and future national physician and NPP workforce. A recent high-profile paper suggested that because of aging of the population and expansion of economic and social expectations, consumers’ demand for physicians, particularly for specialists, is likely to grow.14 Accordingly, among some camps there is a growing call for an expansion in medical training programs. Other analysts believe that the future situation will involve not so much a shortage, but an inappropriate distribution of what by many yardsticks will be an adequate or even abundant supply of providers.15

Although the PGP staffing levels reported here might not translate directly into benchmarks for the United States as a whole, the findings of this paper indicate that U.S. policymakers should deliberate carefully before concluding that expansion of medical training programs is warranted, especially given the huge taxpayer subsidy associated with supporting the training of each new medical professional.

Another potential implication for medical workforce planners is the finding that a sizable proportion of NPPs at the PGPs are practicing outside of primary care. This suggests that the commonly accepted notion that PGPs rely on NPPs mainly for primary care is not necessarily accurate. It is also noteworthy that the total supply of NPs/PAs (26–38 per 100,000) at the PGPs was at or below the current U.S. overall supply ratios (41 per 100,000). This suggests that increased use of NPPs at the PGPs was not the main reason for the lower physician staffing rates. This analysis suggests the need for increased attention to the role of NPPs and their impact on both patients and physicians.

On the surface, workforce planning and forecasting appears to be largely a statistical undertaking—fueled by data, shrouded by minutiae, and confounded by countervailing assumptions. But at its heart, the process is not a technical enterprise. Rather, determining what a nation’s workforce should, could, or would look like ten to twenty years hence is fraught with conceptual, political, and even moral challenges and choices. But this is not to say that these difficult decisions should be made without using any evidence. Analyses such as this one must provide policymakers with information that supports rational decision making. When policymakers are choosing from among the many alternative options, this is the only way that benefits to society can be maximized, whatever the desired (or feasible) level of resource commitment. PGPs have devoted considerable energy to the pursuit of the delicate balance between benefits and costs. Therefore, it seems only fitting that we look to them as a source of guidance as we chart our course toward a more optimal medical workforce.

This project would not have been possible without the full cooperation of the three prepaid group practices that freely “opened their books” for the purpose of this analysis. The author thanks the leadership of both the medical groups and health plans at Kaiser Permanente, Group Health Cooperative, and HealthPartners for this unprecedented support. He also thanks the knowledgeable and cooperative staffs at these organizations that provided administrative data from many parts of their organizations, including Glen Hentges at Kaiser Permanente, Philip Mealand at Group Health Cooperative, and Maureen Peterson and Tammie Lindquist at HealthPartners. Jennifer Neisner of the Kaiser Permanente Institute for Health Policy and Cheryl Kaplowitz at the Johns Hopkins University also played important roles in facilitating this paper at many levels. The editorial assistance of Tracy Lieberman at Johns Hopkins is also gratefully acknowledged. This work was supported in part by a grant from the Kaiser Foundation Health Plan. This work is an independent effort of the author and does not reflect the position of that organization. The paper was derived in part from a chapter by the author in A. Enthoven and L. Tollen, eds., Improving Health Care: The Contributions and Promise of Prepaid Group Practice (Jossey-Bass, forthcoming).

NOTES

1. U.S. Congress, Office of Technology Assessment, Forecasts of Physician Supply and Requirement, Pub. no. USGPO-052-003-00746-1 (Washington: U.S. Government Printing Office, 1980); D. Steinwachs et al., “A Comparison of the Requirements for Primary Care Physicians in HMOs with Projections Made by the GMENAC,” New England Journal of Medicine 314, no. 4 (1986): 217–222; T. Dial et al., “Clinical Staffing in Staff- and Group-Model HMOs,” Health Affairs (Summer 1995): 169–180; D. Goodman et al., “Benchmarking the U.S. Physician Workforce: An Alternative to Needs-Based or Demand-Based Planning,” Journal of the American Medical Association 276, no. 22 (1996): 1811–1844; and H.R. Mason, “Manpower Needs by Specialty,” Journal of the American Medical Association 219, no. 12 (1972): 1621–1626.
2. R. Kronick et al., “The Marketplace in Health Care Reform: The Demographic Limitations of Managed Competition,” New England Journal of Medicine 328, no. 12 (1993): 148–152; J. Weiner, “Forecasting the Effects of Health Reform on U.S. Physician Workforce Requirement: Evidence from HMO Staffing Patterns,” Journal of the American Medical Association 272, no. 3 (1994): 222–230; and A. Tarlov, “HMO Growth and Physicians: The Third Compartment,” Health Affairs (Spring 1986): 23–35.
3. An expanded Exhibit 2, with the specialty-specific physician staffing rates for each of the six Kaiser Permanente regions, is available online at content.healthaffairs.org/cgi/content/full/hlthaff.w4.43v1/DC2.
4. Weiner, “Forecasting the Effects”; J. Weiner, C. McLaughlin, and S. Gamliel, “Extrapolating HMO Staffing to the Population at Large,” in The U.S. Health Workforce: Power, Politics and Policy, ed. M. Osterweis et al. (Washington: Association of Academic Health Centers, 1996), 311–326; and L.G. Hart et al., “Physician Staffing Ratios in Staff-Model HMOs: A Cautionary Tale,” Health Affairs (Jan/Feb 1997): 55–70.
5. Weiner et al., “Extrapolating HMO Staffing to the Population at Large.” This methodology helped to account for potential differences across the two populations within the 65–74 and 75 and older age bands. It did not account for any potential PGP/U.S. population differences in older age groups.
6. Hart et al., “Physician Staffing Ratios.”
7. In the states where the three study sites are located, the rates of physicians per 100,000 population are approximately as follows: Minnesota, 232; Washington, 217; and California, 218. In the metropolitan areas where most of the plans’ enrollees reside, the supply is considerably higher than these state-level rates.
8. Weiner, “Forecasting the Effects.”
9. E. Schaefer and J. Reschovsky, “Are HMO Enrollees Healthier than Others? Results from the Community Tracking Study,” Health Affairs (May/June 2002): 249–259; and F. Hellinger and H. Wong, “Selection Bias in HMOs: A Review of the Evidence,” Medical Care Research and Review 57, no. 4 (2000): 405–439.
10. J. Weiner, “The Demand for Physicians in a Changing Health Care System: A Synthesis,” Medical Care Review 50, no. 4 (1993): 411–449.
11. American Medical Association, Socioeconomic Patterns of Medical Practice in the U.S., 2002/2003 (Chicago: AMA, 2002).
12. P.R. Kletke et al., “The Growing Proportion of Female Physicians: Implications for U.S. Physician Supply,” American Journal of Public Health 80, no. 3 (1990): 300–303.
13. R. Feachem, N. Sekhri, and K. White, “Getting More for Their Dollar: A Comparison of the NHS with California’s Kaiser Permanente,” British Medical Journal 324, no. 19 (2002): 135–143.
14. R. Cooper et al., “Economic and Demographic Trends Signal an Impending Physician Shortage,” Health Affairs (Jan/Feb 2002): 140–154.
15. K. Grumbach, “Fighting Hand to Hand over Physician Workforce Policy,” Health Affairs (Sep/Oct 2002): 13–27; and J. Weiner, “A Shortage of Physicians or a Surplus of Assumptions?” Health Affairs (Jan/Feb 2002): 160–162.

Jonathan Weiner (jweiner{at}jhsph.edu) is a professor and deputy director of the Health Services Research and Development Center, Johns Hopkins Bloomberg School of Public Health, in Baltimore, Maryland.

Please click on the author's names to read related papers by Francis Crosson, W. Bruce Fye, David C. Goodman, Fitzhugh Mullan, Edward Salsberg and Gaetano Forte, and Stephen C. Schoenbaum.


DOI: 10.1377/hlthaff.W4.43
©2004 Project HOPE–The People-to-People Health Foundation, Inc.