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Response to David Meltzer's paper "Hospitalists and the doctor-patient relationship".

The hospitalist movement, in which a generalist physician assumes the physician-of-record role for hospitalized patients in place of the patients' own primary physician is transforming American hospital care. Studies, including those by David Meltzer, support the premise that hospitalist care is less expensive and possibly of higher quality than inpatient care provided by primary physicians. Meltzer's survey of randomly selected individuals indicates that, although many would prefer that their own physician orchestrate their inpatient care, relatively few would pay more than $100 for this privilege. This indicates that patient dissatisfaction with the hospitalist model is unlikely to impede its widespread implementation. Hospitalists are just the latest example of the ongoing tension between generalism and specialization in American medicine. The hospitalist--unlike most traditional medical specialists--is actually a generalist by nature whose specialty is defined by the the site of the care rather than by organ, disease, patient population, or procedure.

Attitude↗

A new statistical test of fitness set data from reciprocal transplant experiments involving intermediate phenotypes.

Experimental biologists use reciprocal transplant experiments (RTEs) involving divergent forms to test hypotheses about fitness trade-offs across, and local adaptation to, native environments. Additional evolutionary hypotheses about diversifying selection, the evolution of specialization, and the coexistence of specialists and generalists are only testable when the RTE also includes intermediate (or alternatively generalist) forms. Environmental variation makes such RTEs challenging, and so strategies that increase their effectiveness are useful. Here, we focus on improvements to the efficiency of RTEs involving intermediate forms with respect to the experimental design and the analysis of the resulting data. We provide a likelihood ratio-based test that offers increased statistical power and robustness relative to another test involving nonlinear regression, when used both for simulated data sets and for data from a study of two divergent fish species and their hybrids transplanted between two lake habitats. The test can be used with unequal numbers of observations, unequal variances, and binomial-type survival data and other nonnormal data. Simulations suggest that having equal numbers of experimental units in each phenotype-environment combination is reasonable. The intentional pairing of observations between environmental conditions (by using clones, full sibs, or half-sibs) is beneficial when paired observations have fitnesses that are negatively related between conditions but is detrimental with positive relatedness. Our methods can be extended to study more than two divergent forms.

Animals↗

Variation in continuous reaction norms: quantifying directions of biological interest.

Thermal performance curves are an example of continuous reaction norm curves of common shape. Three modes of variation in these curves--vertical shift, horizontal shift, and generalist-specialist trade-offs--are of special interest to evolutionary biologists. Since two of these modes are nonlinear, traditional methods such as principal components analysis fail to decompose the variation into biological modes and to quantify the variation associated with each mode. Here we present the results of a new method, template mode of variation (TMV), that decomposes the variation into predetermined modes of variation for a particular set of thermal performance curves. We illustrate the method using data on thermal sensitivity of growth rate in Pieris rapae caterpillars. The TMV model explains 67% of the variation in thermal performance curves among families; generalist-specialist trade-offs account for 38% of the total between-family variation. The TMV method implemented here is applicable to both differences in mean and patterns of variation, and it can be used with either phenotypic or quantitative genetic data for thermal performance curves or other continuous reaction norms that have a template shape with a single maximum. The TMV approach may also apply to growth trajectories, age-specific life-history traits, and other function-valued traits.

Animals↗

Plant population dynamics, pollinator foraging, and the selection of self-fertilization.

Many flowering plants rely on pollinators, self-fertilization, or both for reproduction. We model the consequences of these features for plant population dynamics and mating system evolution. Our mating systems-based population dynamics model includes an Allee effect. This often leads to an extinction threshold, defined as a density below which population densities decrease. Reliance on generalist pollinators who primarily visit higher density plant species increases the extinction threshold, whereas autonomous modes of selfing decrease and can eliminate the threshold. Generalist pollinators visiting higher density plant species coupled with autonomous selfing may introduce an effect where populations decreasing in density below the extinction threshold may nonetheless persist through selfing. The extinction threshold and selfing at low density result in populations where individuals adopting a single reproductive strategy exhibit mating systems that depend on population density. The ecological and evolutionary analyses provide a mechanism where prior selfing evolves even though inbreeding depression is greater than one-half. Simultaneous consideration of ecological and evolutionary dynamics confirms unusual features (e.g., evolution into extinction or abrupt increases in population density) implicit in our separate consideration of ecological and evolutionary scenarios. Our analysis has consequences for understanding pollen limitation, reproductive assurance, and the evolution of mating systems.

Animals↗

Experimental evolution of Pseudomonas fluorescens in simple and complex environments.

In complex environments that contain several substitutable resources, lineages may become specialized to consume only one or a few of them. Here we investigate the importance of environmental complexity in determining the evolution of niche width over approximately 900 generations in a chemically defined experimental system. We propagated 120 replicate lines of the bacterium Pseudomonas fluorescens in environments of different complexity by using between one and eight carbon substrates in each environment. Genotypes from populations selected in complex environments evolved greater mean and variance in fitness than those from populations selected in simple environments. Thus, lineages were able to adapt to several substrates simultaneously without any appreciable loss of function with respect to other substrates present in the media. There was greater genetic and genotype-by-environment interaction variance for fitness within populations selected in complex environments. It is likely that genetic variance in populations grown on complex media was maintained because the identity of the fittest genotype varied among carbon substrates. Our results suggest that evolution in complex environments will result neither in narrow specialists nor in complete generalists but instead in overlapping imperfect generalists, each of which has become adapted to a certain range of substrates but not to all.

Bacterial Typing Techniques↗

The evolution of resource specialization through frequency-dependent and frequency-independent mechanisms.

Levins's fitness set approach has shaped the intuition of many evolutionary ecologists about resource specialization: if the set of possible phenotypes is convex, a generalist is favored, while either of the two specialists is predicted for concave phenotype sets. An important aspect of Levins's approach is that it explicitly excludes frequency-dependent selection. Frequency dependence emerged in a series of models that studied the degree of character displacement of two consumers coexisting on two resources. Surprisingly, the evolutionary dynamics of a single consumer type under frequency dependence has not been studied in detail. We analyze a model of one evolving consumer feeding on two resources and show that, depending on the trait considered to be subject to evolutionary change, selection is either frequency independent or frequency dependent. This difference is explained by the effects different foraging traits have on the consumer-resource interactions. If selection is frequency dependent, then the population can become dimorphic through evolutionary branching at the trait value of the generalist. Those traits with frequency-independent selection, however, do indeed follow the predictions based on Levins's fitness set approach. This dichotomy in the evolutionary dynamics of traits involved in the same foraging process was not previously recognized.

Conservation of Natural Resources↗

A meta-analysis of genetic correlations between plant resistances to multiple enemies.

Genetic correlations between plant resistances to multiple natural enemies are important because they have the potential to determine the mode of selection that natural enemies impose on a host plant, the structure of herbivore and pathogen communities, and the success of plant breeding for resistance to multiple diseases and pests. We conducted a meta-analysis of 29 published studies of 16 different plant species reporting a total of 467 genetic correlations between resistances to multiple herbivores or pathogens. In general, genetic associations between resistances to multiple natural enemies tended to be positive regardless of the breeding design, type of attacker, and type of host plant. Positive genetic correlations between resistances were stronger when both attackers were pathogens or generalist herbivores and when resistance to different enemies was tested independently, suggesting that generalists may be affected by the same plant resistance traits and that interactions among natural enemies are common. Although the mean associations between resistances were positive, indicating the prevalence of diffuse selection and generalized defenses against multiple enemies, the large variation in both the strength and the direction of the associations suggests a continuum between pairwise and diffuse selection.

Animals↗

Ecological specialization and adaptive decay in digital organisms.

The transition from generalist to specialist may entail the loss of unused traits or abilities, resulting in narrow niche breadth. Here we examine the process of specialization in digital organisms--self-replicating computer programs that mutate, adapt, and evolve. Digital organisms obtain energy by performing computations with numbers they input from their environment. We examined the evolutionary trajectory of generalist organisms in an ecologically narrow environment, where only a single computation yielded energy. We determined the extent to which improvements in this one function were associated with losses of other functions, leading to organisms that were highly specialized to perform only one or a few functions. Our results show that as organisms evolved improved performance of the selected function, they often lost the ability to perform other computations, and these losses resulted most often from the accumulation of neutral and deleterious mutations. Beneficial mutations, although relatively rare, were disproportionately likely to cause losses of function, indicating that antagonistic pleiotropy contributed significantly to niche breadth reductions in this system. Occasionally, unused functions were not lost and even increased in performance. Here we find that understanding how the functions were integrated into the genome was crucial to predictions of their maintenance.

Adaptation, Biological↗

Personality characteristics and expressed career choice of graduating physical therapy students.

We examined the personality characteristics of physical therapy students (N = 45) who had different career goals. We used the Myers-Briggs Type Indicator and a brief demographic information sheet to collect data at the conclusion of the 1982 spring semester. Analyses of variance indicated statistically significant differences (p less than .01) between those who desired careers as generalist clinicians versus specialist clinicians. The specialist group represented adaptive, curious problem solvers; the generalists demonstrated characteristics of precision, order, and preferences for routine procedure. The findings have implications for the job satisfaction of physical therapists and have ramifications for curriculum planning.

Career Choice↗

Training an appropriate mix of physicians to meet the nation's needs.

Although the lack of a national policy on medical manpower has served U.S. medicine well in some ways, it also has created problems, the most important of which is the maldistribution of physicians in the various specialties, with too many specialists and not nearly enough generalists. The author explains why this imbalance is a problem and why it is receiving so much attention, describes three types of forces--economic, practice-related, and scientific--that favor the practice of specialty medicine, and demonstrates that the medical school experience itself may be a critical influence on students' career decisions. He then outlines possible ways to correct the imbalance, both outside and inside academic medicine; for the latter sphere, he proposes five detailed alternative scenarios of how corrective change might come about, which range from doing nothing to making a number of fundamental changes within academic medicine's institutions to having external financial pressures for change brought to bear by the states and the federal government. In conclusion, the author notes that some combination of these scenarios will occur, because spending for medical care in the United States is out of control and cannot be reduced unless the distribution of physicians by specialty is rebalanced to have a much greater percentage of generalists. His hope is that academic medicine will accept this challenge and bring about the best mix of physicians to meet the nation's needs.

Academic Medical Centers↗

Graduate medical education consortia: expectations and experiences.

Graduate medical education (GME) consortia are formal associations of medical schools, teaching hospitals, and other organizations involved in residency training, with central support, direction, and coordination allowing members to function collectively. GME consortia are not well documented in the literature, although they are included in many GME reform proposals. Proponents expect consortia to improve the organizational structure and governance of residency training programs and, through local coordination and possibly the allocation of resources, to help members meet national workforce goals regarding both numbers and practice locations for generalist and specialist physicians. The authors contrast the expectations of educators and policymakers for the future performance of GME consortia with the experiences of 36 functioning consortia, gathered in a 1993 national survey conducted by the Maine Medical Center and the Association of American Medical Colleges. Respondents account for nearly 10% of all residency training programs and 17% of all residents nationwide. The participating consortia differ markedly in their structures, functions, and other features, although nearly 85% have been convened by medical schools and closely affiliated hospitals. Fewer than half function with governing boards; 40% offer a single integrated residency training program in each discipline; and 58% allocate resources. A common concern of consortium members was physician distribution by specialty, but only 31% identified "increasing the number of generalist physicians" as a major accomplishment to date. To improve their performance, consortium participants call for greater commitment and leadership from the medical school and university, better definition of the community's GME needs, more information about the flow of GME funds locally, greater authority to allocate resources, and incentives for shifting allegiances from individual institutions to the consortium community as a whole.

Data Collection↗

Health care reform continues: themes for academic medicine.

The challenge for U.S. academic medicine in this decade is to redesign itself to serve its classic functions--teaching, research, and special service to patients--while filling the needs of what is evolving into a comprehensive integrated system of health care. First, in the absence of federally legislated comprehensive health care reform, the health care community must develop a consensus on the purposes, scope, and content of health care to bring some reason and order to the short-term, market-driven incrementalism that governs today's health care. Specifically, the author proposes that the issues of health care be defined in a broad social context, that the gap between public health and medicine be lessened, and that perspectives of public health and health promotion and disease prevention be more effectively incorporated into medical education. Second, there is an urgent need for new approaches to funding and financial management of teaching, research, and patient care in academic health centers to counter the erosion of traditional sources of support. Third, to sustain generalist physician practices of high quality, a conceptual basis for generalism must be defined in affirmative functional terms, and the generalist's frame of reference and intellectual tools and processes must be formulated. Last, many forces are now acting to reduce the intellectual content of medical practice and teaching. Academic medicine--in teaching and in research--must nurture and promote the intellectual content and standards of all aspects of medicine to sustain the quality of clinical practice over time.(ABSTRACT TRUNCATED AT 250 WORDS)

Academic Medical Centers↗

The kaleidoscope of general internist careers: a challenge for internal medicine training.

As internal medicine residency programs struggle to produce general internists in greater numbers and assure that they are adequately prepared for practice, it is imperative that the graduate medical education system have a clear picture of what competencies will be expected of those entering general internist careers. Feedback from the practicing community and large managed care organizations in Minnesota has made it clear that general internists in that state are functioning in a variety of positions requiring a wide range of skills depending on the practice description, choice of practice setting, and the complement of other primary care providers. General internists functioning in nontraditional careers have special curricular needs. It is imperative that training programs constantly monitor the changing practice environment and stay current on the variety of new generalist career choices to adequately prepare their residents for generalist careers. The graduate medical education enterprise needs to be involved in determining the best teaching strategies for the broad range of ambulatory general medicine competencies and in determining how best to preserve the richness of the medical subspecialty experience critical to the training of excellent general internists.

Career Choice↗

Influence of medical school curriculum on primary care specialty choice: analysis and synthesis of the literature.

There is a growing consensus that the proportion of primary care physicians in the United States is inadequate to meet health care needs. Many graduating medical students continue to choose to subspecialize. The literature on curriculum and specialty choice is fraught with confounders and a lack of randomized trials, and recommendations for strategies to increase the production of generalists have not been based on clear evidence that the interventions will be effective, thus making it difficult for medical schools to react responsibly to these recommendations. To assist educators and policymakers in their efforts to produce more generalists, the author critically reviewed the literature on curriculum and primary care specialty choice from 1982 through April 1993. A literature search was conducted using the MEDLINE, Educational Resources Information Center, and PsychInfo databases. Of more than 150 studies found in the search, 31 were determined to be relevant and to meet inclusion criteria. The results confirm that the determinants of specialty choice are multifactorial and that there are many weaknesses in the published literature, making interpretation difficult. Important trends did emerge, however, providing direction for intervention and recommendations for further investigation. The evidence suggests that three types of curricular experiences may increase interest in primary care: third-year required family medicine clerkships (especially those that are six, rather than four, weeks long), continuity experiences in primary care settings, and, most promising of all, primary care tracks.

Career Choice↗

A national study of the factors influencing men and women physicians' choices of primary care specialties.

BACKGROUND: Despite a recent increase in the percentage of graduating U.S. medical students planning to pursue generalist careers, interest in primary care among students is still far below what it was in the early 1980s and falls well short of the stated goal of the Association of American Medical Colleges that half of all graduates should choose generalist careers. Also during the past decade, the number of women students and physicians has increased. Given the importance of concerns regarding the primary care work force, it is timely to examine the relationship between gender and other factors that influence the decision to enter primary care. METHOD: Totals of 1,038 (65%) men and 558 (35%) women primary care physicians selected from the 1983 and 1984 graduates of all allopathic U.S. medical schools were surveyed in early 1993. Gender comparisons were made on the 19 variables that influenced the physicians' decisions to enter primary care specialties and on the six factor scores derived from a factor analysis of these 19 variables. Also included in the gender comparisons were characteristics of practice, populations served, timing of making the decision to enter primary care, and personal demographic information. RESULTS: Men, more than women, were influenced to become primary care physicians by early role models. Women, more than men, were influenced by personal and family factors. Overall, medical school experience and personal values are two important factors that explained the largest variances of the 19 predictor variables influencing the physicians' choices of primary care disciplines. There was no gender difference in place of origin, family income as a child, timing of the decision to become a primary care physician, or the amount of debt upon graduation. CONCLUSION: This nationwide study of primary care physicians indicates that men and women physicians differ in their perceptions of the relative importances of factors influencing the choice of a primary care specialty. Gender-specific factors should receive more attention in the development of successful strategies to attract more medical students into primary care specialties.

Career Choice↗

Will competition change the physician workforce? Early signals from the market.

Many policymakers and researchers agree that there are problems of physician oversupply and imbalance in specialty mix. Some have argued that these will be resolved as a more competitive health care market develops, predicting that cost-conscious integrated systems will change demands for physician's services. As a result, physicians will experience unemployment or lower incomes, sending a signal to students and educators to change behavior. Although anecdotes abound, there has been no systematic assessment of what changes in the organization and financing of health care are actually doing to the physician labor market. This article considers potential indicators of changes and reviews what these indicators are now showing. Two types of change are assessed: whether increasing demand for generalists is changing specialty mix, and whether the market is creating incentives to train fewer physicians overall. There have been some changes in the market, but it is still too early to know whether they signal a departure from previous trends. Positions in generalist fields are becoming somewhat more attractive, but changes in incomes have been modest and the number of specialists continues to increase. There is also little indication that job opportunities for physicians are contracting.

Career Choice↗

Sustaining the development of primary care in academic medicine. Working Group on Sustaining the Development of Academic Primary Care. Association of American Medical Colleges.

This article is the report of the Working Group on Sustaining the Development of Academic Primary Care, one of the six subgroups of the Advisory Panel on the Mission and Organization of Medical Schools (APMOMS) sponsored by the Association of American Medical Colleges (AAMC). To begin, the group draws a distinction between primary care and generalism. Primary care is a core domain of health care and, in the context of emerging integrated systems, will increasingly be a multidisciplinary shared function. Non-subspecialized physicians, or "generalists," are a key element in the provision of primary care, but do not act alone. Core competencies for primary care are central to the education of all physicians. Therefore, irrespective of workforce goals for generalist physicians, primary care should have a strong, central position in the medical school so that graduates can receive a sound general medical education and can be prepared for any specialty and for lifelong learning in an evolving health care system. For primary care to achieve that position, medical schools must integrate primary care into their missions, strategic plans, operation, organization, academic administrative structures, curriculum development, faculty development (both school- and community-based), resource development, alliances with appropriate clinical services networks, financial policy, and evaluation and educational monitoring systems. The group briefly describes the elements of those changes and also proposes ways that the AAMC and medical school leaders could promote the central role of primary care in medical schools.

Curriculum↗

Debt management and financial planning support for primary care students and residents at Boston University School of Medicine.

Boston University Medical Center created the Office of Residency Planning and Practice Management as part of The Robert Wood Johnson Foundation's Generalist Physician Initiative. Since 1995, the office has improved the medical center's ability to promote and support the generalist career decisions of its students and residents by removing indebtedness as a disincentive. After a brief review of the relationship between indebtedness and specialty selection, the authors delineate the nature and volume of debt-management assistance provided by the office to students and residents through individual counseling sessions, workshops, and other means between April 1995 and March 1998. A case study shows the progression of these services throughout residency training. The medical center also coordinates its debt-management assistance with counseling from physician-oriented financial planning groups. In conclusion, the authors discuss several characteristics of a successful debt-management program for residents.

Boston↗