Chapter 1. The Practice of Medicine

The Modern-Day Physician No greater opportunity, responsibility, or obligation can fall to the lot of a human being than to become a physician. In the care of the suffering, [the physician] needs technical skill, scientific knowledge, and human understanding. . .. Tact, sympathy, and understanding are expected of the physician, for the patient is no mere collection of symptoms, signs, disordered functions, damaged organs, and disturbed emotions. [The patient] is human, fearful, and hopeful, seeking relief, help, and reassurance. —Harrison's Principles of Internal Medicine, 1950 The practice of medicine has changed in significant ways since the first edition of this book appeared more than 60 years ago. The advent of molecular genetics, molecular biology, and molecular pathophysiology, sophisticated new imaging techniques, and advances in bioinformatics and information technology have contributed to an explosion of scientific information that has fundamentally changed the way physicians define, diagnose, treat, and prevent disease. This growth of scientific knowledge is ongoing and accelerating. The widespread use of electronic medical records and the Internet have altered the way doctors practice medicine and exchange information. As today's physician struggles to integrate copious amounts of scientific knowledge into everyday practice, it is important to remember that the ultimate goal of medicine is to prevent disease and treat sick patients. Despite more than 60 years of scientific advances since the first edition of this text, it is critical to underscore that cultivating the intimate relationship between physician and patient still lies at the heart of successful patient care. The Science and Art of Medicine Deductive reasoning and applied technology form the foundation for the solution to many clinical problems. Spectacular advances in biochemistry, cell biology, and genomics, coupled with newly developed imaging techniques, allow access to the innermost parts of the cell and provide a window to the most remote recesses of the body. Revelations about the nature of genes and single cells have opened the portal for formulating a new molecular basis for the physiology of systems. Increasingly, physicians are learning how subtle changes in many different genes can affect the function of cells and organisms. Researchers are beginning to decipher the complex mechanisms by which genes are regulated. Doctors have developed a new appreciation of the role of stem cells in normal tissue function and in the development of cancer, degenerative disease, and other disorders, as well as their emerging role in the treatment of certain diseases. The knowledge gleaned from the science of medicine has already improved and undoubtedly will further improve physicians' understanding of complex disease processes and provide new approaches to disease treatment and prevention. Yet, skill in the most sophisticated application of laboratory technology and in the use of the latest therapeutic modality alone does not make a good physician. When a patient poses challenging clinical problems, an effective physician must be able to identify the crucial elements in a complex history and physical examination; order the appropriate laboratory, imaging, and diagnostic tests; and extract the key results from the crowded computer printouts of data to determine whether to "treat" or to "watch." Deciding whether a clinical clue is worth pursuing or should be dismissed as a "red herring" and weighing whether a proposed test, preventive measure, or treatment entails a greater risk than the disease itself are essential judgments that a skilled clinician must make many times each day. This combination of medical knowledge, intuition, experience, and judgment defines the art of medicine, which is as necessary to the practice of medicine as is a sound scientific base.

Clinical Skills History-Taking The written history of an illness should include all the facts of medical significance in the life of the patient. Recent events should be given the most attention. The patient should, at some early point, have the opportunity to tell his or her own story of the illness without frequent interruption and, when appropriate, receive expressions of interest, encouragement, and empathy from the physician. Any event related by the patient, however trivial or seemingly irrelevant, may provide the key to solving the medical problem. In general, only patients who feel comfortable with the physician will offer complete information, and thus putting the patient at ease to the greatest extent possible contributes substantially to obtaining an adequate history. An informative history is more than an orderly listing of symptoms; by listening to patients and noting the way in which they describe their symptoms, physicians can gain valuable insight into the problem. Inflections of voice, facial expression, gestures, and attitude, i.e., "body language," may reveal important clues to the meaning of the symptoms to the patient. Because patients vary in their medical sophistication and ability to recall facts, the reported medical history should be corroborated whenever possible. The social history also can provide important insights into the types of diseases that should be considered. The family history not only identifies rare Mendelian disorders within a family but often reveals risk factors for common disorders, such as coronary heart disease, hypertension, and asthma. A thorough family history may require input from multiple relatives to ensure completeness and accuracy, and once recorded, it can be updated readily. The process of history-taking provides an opportunity to observe the patient's behavior and watch for features to be pursued more thoroughly during the physical examination. The very act of eliciting the history provides the physician with an opportunity to establish or enhance the unique bond that forms the basis for the ideal patient-physician relationship. This process helps the physician develop an appreciation of the patient's perception of the illness, the patient's expectations of the physician and the health care system, and the financial and social implications of the illness to the patient. Although current health care settings may impose time constraints on patient visits, it is important not to rush the history-taking since this may lead the patient to believe that what he or she is relating is not of importance to the physician and, therefore, may withhold relevant information. The confidentiality of the patient-physician relationship cannot be overemphasized. Physical Examination The purpose of the physical examination is to identify the physical signs of disease. The significance of these objective indications of disease is enhanced when they confirm a functional or structural change already suggested by the patient's history. At times, however, the physical signs may be the only evidence of disease. The physical examination should be performed methodically and thoroughly, with consideration for the patient's comfort and modesty. Although attention is often directed by the history to the diseased organ or part of the body, the examination of a new patient must extend from head to toe in an objective search for abnormalities. Unless the physical examination is systematic and is performed in a consistent manner from patient to patient, important segments may be omitted inadvertently. The results of the examination, like the details of the history, should be recorded at the time they are elicited, not hours later, when they are subject to the distortions of memory. Skill in physical diagnosis is acquired with experience, but it is not merely technique that determines success in eliciting signs of disease. The detection of a few scattered petechiae, a faint diastolic murmur, or a small mass in the abdomen is not a question of keener eyes and ears or more sensitive fingers but of a mind alert to those findings. Because physical findings can change with time, the physical examination should be repeated as frequently as the clinical situation warrants. Because a large number of highly sensitive diagnostic tests are available, particularly imaging techniques, it may be tempting to put less emphasis on the physical examination. Indeed, many patients are seen for the first time after a series of diagnostic tests have been performed and the results are known. This fact should not deter the physician from performing a thorough physical examination since clinical findings are often present that have "escaped" the barrage of preexamination diagnostic tests. The act of examining (touching) the patient also offers an opportunity for communication and may have reassuring effects that foster the patient-physician relationship. Diagnostic Studies Physicians have become increasingly reliant on a wide array of laboratory tests to solve clinical problems. However, accumulated laboratory data do not relieve the physician from the responsibility of carefully observing, examining, and studying the patient. It is also essential to appreciate the limitations of diagnostic tests. By virtue of their impersonal quality, complexity, and apparent precision, they often gain an aura of authority regardless of the fallibility of the tests, the instruments used in the tests, and the individuals performing or interpreting them. Physicians must weigh the expense involved in the laboratory procedures against the value of the information they are likely to provide. Single laboratory tests are rarely ordered. Instead, physicians generally request "batteries" of multiple tests, which often prove useful. For example, abnormalities of hepatic function may provide the clue to nonspecific symptoms such as generalized weakness and increased fatigability, suggesting the diagnosis of chronic liver disease. Sometimes a single abnormality, such as an elevated serum calcium level, points to a particular disease, such as hyperparathyroidism or an underlying malignancy. The thoughtful use of screening tests such as low-density lipoprotein cholesterol may be quite useful. A group of laboratory determinations can be carried out conveniently on a single specimen at relatively low cost. Screening tests are most informative when directed toward common diseases or disorders and when their results indicate the need for other useful tests or interventions that may be costly to perform. On the one hand, biochemical measurements, together with simple laboratory examinations such as blood count, urinalysis, and sedimentation rate, often provide a major clue to the presence of a pathologic process. On the other hand, the physician must learn to evaluate occasional abnormalities among the screening tests that may not necessarily connote significant disease. An in-depth workup after a report of an isolated laboratory abnormality in a person who is otherwise well is almost invariably wasteful and unproductive. Because so many tests are performed routinely as screening, it would not be unusual for one or two of them to be slightly abnormal. If there is no suspicion of an underlying illness, these tests ordinarily are repeated to ensure that the abnormality does not represent a laboratory error. If an abnormality is confirmed, it is important to consider its potential significance in the context of the patient's condition and other test results. The development of technically improved imaging studies with greater sensitivity and specificity is one of the most rapidly advancing areas of medicine. These tests provide remarkably detailed anatomic information that can be a pivotal factor in medical decision-making. Ultrasonography, a variety of isotopic scans, CT, MRI, and positron emission tomography have benefited patients by supplanting older, more invasive approaches and opening new diagnostic vistas. In light of their capabilities and the rapidity with which they can lead to a diagnosis, it is tempting to order a battery of imaging studies. All physicians have had experiences in which imaging studies turned up findings that led to an unexpected diagnosis. Nonetheless, patients must endure each of these tests, and the added cost of unnecessary testing is substantial. Furthermore, investigation of an unexpected abnormal finding may be associated with risk and/or expense and may lead to the diagnosis of an irrelevant or incidental problem. A skilled physician must learn to use these powerful diagnostic tools judiciously, always considering whether the results will alter management and benefit the patient.

Principles of Patient Care Evidence-Based Medicine Evidence-based medicine refers to the concept that clinical decisions are formally supported by data, preferably data that are derived from prospectively designed, randomized, controlled clinical trials. This approach is in sharp contrast to anecdotal experience, which often may be biased. Unless they are attuned to the importance of using larger, more objective studies for making decisions, even the most experienced physicians can be influenced by recent encounters with selected patients. Evidence-based medicine has become an increasingly important part of the routine practice of medicine and has led to the publication of a number of practice guidelines. Practice Guidelines Professional organizations and government agencies are developing formal clinical-practice guidelines to aid physicians and other caregivers in making diagnostic and therapeutic decisions that are evidence-based, cost-effective, and most appropriate to a particular patient and clinical situation. As the evidence base of medicine increases, guidelines can provide a useful framework for managing patients with particular diagnoses or symptoms. They can protect patients—particularly those with inadequate health care benefits—from receiving substandard care. Guidelines also can protect conscientious caregivers from inappropriate charges of malpractice and society from the excessive costs associated with the overuse of medical resources. There are, however, caveats associated with clinical-practice guidelines since they tend to oversimplify the complexities of medicine. Furthermore, groups with differing perspectives may develop divergent recommendations regarding issues as basic as the need for mammographic screening of women in their forties or a prostate-specific antigen (PSA) assay in the serum of men over age 50. Finally, guidelines do not—and cannot be expected to—account for the uniqueness of each individual and his or her illness. The physician's challenge is to integrate into clinical practice the useful recommendations offered by experts without accepting them blindly or being inappropriately constrained by them. Medical Decision-Making Medical decision-making is an important responsibility of the physician and occurs at each stage of the diagnostic and treatment process. It involves the ordering of additional tests, requests for consults, and decisions regarding treatment and prognosis. This process requires an in-depth understanding of the pathophysiology and natural history of disease. As described above, medical decision-making should be evidence-based so that patients derive the full benefit of the scientific knowledge available to physicians. Formulating a differential diagnosis requires not only a broad knowledge base but also the ability to assess the relative probabilities of various diseases. Application of the scientific method, including hypothesis formation and data collection, is essential to the process of accepting or rejecting a particular diagnosis. Analysis of the differential diagnosis is an iterative process. As new information or test results are acquired, the group of disease processes being considered can be contracted or expanded appropriately. Despite the importance of evidence-based medicine, much of medical decision-making relies on good clinical judgment, a process that is difficult to quantify or even to assess qualitatively. Physicians must use their knowledge and experience as a basis for weighing known factors along with the inevitable uncertainties and the need to use sound judgment; this synthesis of information is particularly important when a relevant evidence base is not available. Several quantitative tools may be invaluable in synthesizing the available information, including diagnostic tests, Bayes' theorem, and multivariate statistical models. Diagnostic tests serve to reduce uncertainty about a diagnosis or prognosis in a particular individual and help the physician decide how best to manage that individual's condition. The battery of diagnostic tests complements the history and the physical examination. The accuracy of a particular test is ascertained by determining its sensitivity (true-positive rate) and specificity (true-negative rate) as well as the predictive value of a positive and a negative result. Bayes' theorem uses information on a test's sensitivity and specificity, in conjunction with the pretest probability of a diagnosis, to determine mathematically the posttest probability of the diagnosis. More complex clinical problems can be approached with multivariable statistical models, which generate highly accurate information even when multiple factors are acting individually or together to affect disease risk, progression, or response to treatment. Studies comparing the performance of statistical models with that of expert clinicians have documented equivalent accuracy, although the models tend to be more consistent. Thus, multivariate statistical models may be particularly helpful to less experienced clinicians. See Chap. 3 for a more thorough discussion of decision-making in clinical medicine. Electronic Medical Records Growing reliance on computers and the strength of information technology are playing an increasingly important role in medicine. Laboratory data are accessed almost universally through computers. Many medical centers now have electronic medical records, computerized order entry, and bar-coded tracking of medications. Some of these systems are interactive and provide reminders or warn of potential medical errors. In many ways, the health care system has lagged behind other industries in the adoption of information technology. Electronic medical records have extraordinary potential for providing rapid access to clinical information, imaging studies, laboratory results, and medications. This type of information is invaluable for ongoing efforts to enhance quality and improve patient safety. Ideally, patient records should be easily transferred across the health care system, providing reliable access to relevant data and historic information. However, technology limitations and concerns about privacy and cost continue to limit a broad-based utilization of electronic health records in most clinical settings. It also should be emphasized that information technology is merely a tool and can never replace the clinical decisions that are best made by the physician. In this regard, clinical knowledge and an understanding of the patient's needs, supplemented by quantitative tools, still seem to represent the best approach to decision-making in the practice of medicine. Evaluation of Outcomes Clinicians generally use objective and readily measurable parameters to judge the outcome of a therapeutic intervention. For example, findings on physical or laboratory examination—such as the blood pressure level, the patency of a coronary artery on an angiogram, or the size of a mass on a radiologic examination—can provide critically important information. However, patients usually seek medical attention for subjective reasons; they wish to obtain relief from pain, preserve or regain function, and enjoy life. The components of a patient's health status or quality of life can include bodily comfort, capacity for physical activity, personal and professional function, sexual function, cognitive function, and overall perception of health. Each of these important areas can be assessed by means of structured interviews or specially designed questionnaires. Such assessments also provide useful parameters by which the physician can judge the patient's subjective view of his or her disability and the response to treatment, particularly in chronic illness. The practice of medicine requires consideration and integration of both objective and subjective outcomes. Women's Health and Disease Although past epidemiologic studies and clinical trials often focused predominantly on men, more recent studies have included more women, and some, like the Women's Health Initiative, have exclusively addressed women's health issues. Significant gender differences exist in diseases that afflict both men and women. Much is still to be learned in this arena, and ongoing studies should enhance physicians' understanding of the mechanisms of gender differences in the course and outcome of certain diseases. For a more complete discussion of women's health, see Chap. 6. Care of the Elderly The relative proportion of elderly individuals in the populations of developed nations has been growing considerably over the last few decades and will continue to grow. In this regard, the practice of medicine will continue to be greatly influenced by the health care needs of this growing elderly population. The physician must understand and appreciate the decline in physiologic reserve associated with aging; the diminished responses of the elderly to vaccinations such as those against influenza; the different responses of the elderly to common diseases; and disorders that occur commonly with aging, such as depression, dementia, frailty, urinary incontinence, and fractures. For a more complete discussion of medical care for the elderly, see Part 5, Chaps. 70, 71, and 72. Errors in the Delivery of Health Care A report from the Institute of Medicine called for an ambitious agenda to reduce medical error rates and improve patient safety by designing and implementing fundamental changes in health care systems. Adverse drug reactions occur in at least 5% of hospitalized patients, and the incidence increases with the use of a large number of drugs. No matter what the clinical situation is, it is the responsibility of the physician to use powerful therapeutic measures wisely, with due regard for their beneficial action, potential dangers, and cost. It is also the responsibility of hospitals and health care organizations to develop systems to reduce risk and ensure patient safety. Medication errors can be reduced through the use of ordering systems that eliminate misreading of handwriting. Implementation of infection control systems, enforcement of hand washing protocols, and careful oversight of antibiotic use can minimize the complications of nosocomial infections. The Role of the Physician in the Informed Consent of the Patient The fundamental principles of medical ethics require physicians to act in the patient's best interest and respect the patient's autonomy. This is particularly relevant to the issue of informed consent. Most patients possess only limited medical knowledge and must rely on their physicians for advice. Physicians must respect their patients' autonomy, fully discussing the alternatives for care and the risks, benefits, and likely consequences of each alternative. Special care should be taken to ensure that a physician seeking a patient's informed consent does not have a real or apparent conflict of interest involving personal gain. Patients are required to sign a consent form for essentially any diagnostic or therapeutic procedure. In such cases, it is particularly important for the patient to understand clearly the risks and benefits of these procedures; this is the definition of informed consent. It is incumbent on the physician to explain the procedures in a clear and understandable manner and to ascertain that the patient comprehends both the nature of the procedure and the attendant risks and benefits. The dread of the unknown, inherent in hospitalization, can be mitigated by such explanations. The Approach to Grave Prognoses and Death No problem is more distressing than the diagnosis of an incurable disease, particularly when premature death is inevitable. What should the patient and family be told? What measures should be taken to maintain life? What can be done to maintain the quality of life? Although some would argue otherwise, there is no ironclad rule that the patient must immediately be told "everything" even if the patient is an adult with substantial family responsibilities. Nevertheless, openness and honesty with the patient is a must. A patient must know the expected course of disease to make appropriate plans and preparations. The patient should participate in decision-making with an understanding of the treatment goals (cure or palliation), the disease effects, and the likely treatment effects. A wise and insightful physician often is guided by an understanding of what a patient wants to know and when he or she wants to know it. The patient's religious beliefs also may be taken into consideration. The patient must be given an opportunity to talk with the physician and ask questions. Patients may find it easier to share their feelings about death with their physician, who is likely to be more objective and less emotional, than with family members. As William Osler wrote, "One thing is certain; it is not for you to don the black cap and, assuming the judicial function, take hope away from any patient." Even when the patient directly inquires, "Am I dying?" the physician must attempt to determine whether this is a request for information or for reassurance. Only open communication between the patient and the physician can resolve this question and guide the physician in what to say and how to say it. The physician should provide or arrange for emotional, physical, and spiritual support and must be compassionate, unhurried, and open. There is much to be gained by the laying on of hands. Pain should be controlled adequately, human dignity maintained, and isolation from family and close friends avoided. These aspects of care tend to be overlooked in hospitals, where the intrusion of life-sustaining apparatus can detract from attention to the whole person and encourage concentration instead on the life-threatening disease, against which the battle ultimately will be lost in any case. In the face of terminal illness, the goal of medicine must shift from cure to care in the broadest sense of the term. Primum succurrere, first hasten to provide help, is a guiding principle. In offering care to a dying patient, a physician must be prepared to provide information to family members and deal with their grief and sometimes their feelings of guilt. It is important for the doctor to assure the family that everything possible has been done. For a more complete discussion of end-of-life care, see Chap. 9.

The Patient-Physician Relationship The significance of the intimate personal relationship between physician and patient cannot be too strongly emphasized, for in an extraordinarily large number of cases both the diagnosis and treatment are directly dependent on it. One of the essential qualities of the clinician is interest in humanity, for the secret of the care of the patient is in caring for the patient. —Francis W. Peabody, 1881–1927 Physicians must never forget that patients are individual human beings with problems that all too often transcend their physical complaints. They are not "cases" or "admissions" or "diseases." Patients do not fail treatments; treatments fail to benefit patients. This point is particularly important in this era of high technology in clinical medicine. Most patients are anxious and fearful. Physicians should instill confidence and should be reassuring but should never be arrogant. A professional attitude, coupled with warmth and openness, can do much to alleviate anxiety and to encourage patients to share all aspects of their medical history. Empathy and compassion are the essential features of a caring physician. Whatever the patient's attitude is, the physician needs to consider the setting in which an illness occurs—in terms not only of the patients themselves but also of their familial, social, and cultural backgrounds. The ideal patient-physician relationship is based on thorough knowledge of the patient, mutual trust, and the ability to communicate. The Dichotomy of Inpatient and Outpatient Internal Medicine The hospital environment has changed dramatically over the last few decades. In more recent times, emergency departments and critical care units have evolved to identify and manage critically ill patients, allowing them to survive formerly fatal diseases. There is increasing pressure to reduce the length of stay in the hospital and to manage complex disorders in the outpatient setting. This transition has been driven not only by efforts to reduce costs but also by the availability of new outpatient technologies, such as imaging and percutaneous infusion catheters for long-term antibiotics or nutrition, minimally invasive surgical procedures, and evidence that outcomes often are improved by minimizing inpatient hospitalization. Hospitals now consist of multiple distinct levels of care, such as the emergency department, procedure rooms, overnight observation units, critical care units, and palliative care units, in addition to traditional medical beds. A consequence of this differentiation has been the emergence of new specialties such as emergency medicine, intensivists, hospitalists, and end-of-life care. Moreover, these systems frequently involve "handoffs" from the outpatient to the inpatient environment, from the critical care unit to a general medicine floor, and from the hospital to the outpatient environment. Clearly, one of the important challenges in internal medicine is to maintain continuity of care and information flow during these transitions, which threaten the traditional one-to-one relationship between patient and physician. In the current environment, teams of physicians, specialists, and other health care professionals often replace the personal interaction between doctor and patient. The patient can benefit greatly from effective collaboration among a number of health care professionals; however, it is the duty of the patient's principal or primary physician to provide cohesive guidance through an illness. To meet this challenge, the primary physician must be familiar with the techniques, skills, and objectives of specialist physicians and allied health professionals. The primary physician must ensure that the patient will benefit from scientific advances and from the expertise of specialists when they are needed while retaining responsibility for the major decisions concerning diagnosis and treatment. Appreciation of the Patient's Hospital Experience The hospital is an intimidating environment for most individuals. Hospitalized patients find themselves surrounded by air jets, buttons, and glaring lights; invaded by tubes and wires; and beset by the numerous members of the health care team—nurses, nurses' aides, physicians' assistants, social workers, technologists, physical therapists, medical students, house officers, attending and consulting physicians, and many others. They may be transported to special laboratories and imaging facilities replete with blinking lights, strange sounds, and unfamiliar personnel; they may be left unattended for periods of time; they may be obliged to share a room with other patients, who have their own health problems. It is little wonder that patients may lose their sense of reality. Physicians who can appreciate the hospital experience from the patient's perspective and make an effort to develop a strong personal relationship with the patient in which they may guide the patient through this experience can make a stressful situation more tolerable. Trends in the Delivery of Health Care: A Challenge to the Humane Physician Many trends in the delivery of health care tend to make medical care impersonal. These trends, some of which have been mentioned already, include  (1) vigorous efforts to reduce the escalating costs of health care;  (2) the growing number of managed-care programs, which are intended to reduce costs but in which the patient may have little choice in selecting a physician or in seeing that physician consistently;  (3) increasing reliance on technological advances and computerization for many aspects of diagnosis and treatment; (4) the need for numerous physicians to be involved in the care of most patients who are seriously ill; and (5) an increased number of malpractice suits, some of which are justifiable because of medical errors but others of which reflect an unrealistic expectation on the part of many patients that their disease will be cured or that complications will not occur during the course of complex illnesses or procedures. In light of these changes in the medical care system, it is a major challenge for physicians to maintain the humane aspects of medical care. The American Board of Internal Medicine, working together with the American College of Physicians–American Society of Internal Medicine and the European Federation of Internal Medicine, has published a Charter on Medical Professionalism that underscores three main principles in physicians' contract with society:  (1) the primacy of patient welfare, (2) patient autonomy, and  (3) social justice. Medical schools appropriately place substantial emphasis on physician professionalism (Fig. 1-1). The humanistic qualities of a physician must encompass integrity, respect, and compassion. Availability, the expression of sincere concern, the willingness to take the time to explain all aspects of the illness, and a nonjudgmental attitude when dealing with patients whose cultures, lifestyles, attitudes, and values differ from those of the physician are just a few of the characteristics of a humane physician. Every physician will, at times, be challenged by patients who evoke strongly negative or positive emotional responses. Physicians should be alert to their own reactions to such patients and situations and consciously monitor and control their behavior so that the patient's best interest remains the principal motivation for their actions at all times.

Figure 1-1

A typical "white coat" ceremony in medical school in which students are introduced to the responsibilities of patient care. (Photo courtesy of Suzanne Camarata Photography; used with permission.)

An important aspect of patient care involves an appreciation of the patient's "quality of life," a subjective assessment of what each patient values most. This assessment requires detailed, sometimes intimate knowledge of the patient, which usually can be obtained only through deliberate, unhurried, and often repeated conversations. Time pressures will always threaten these interactions, but they should not diminish the importance of understanding and seeking to fulfill the priorities of the patient.

The Twenty-First-Century Physician: Expanding Frontiers The era of "omics": genomics, epigenomics, proteomics, microbiomics, metagenomics, metabolomics . . . In the spring of 2003, the complete sequencing of the human genome was announced, officially ushering in the genomic era. However, even before that landmark accomplishment, the practice of medicine had been evolving as a result of the insights gained from an understanding of the human genome as well as the genomes of a wide variety of microbes, whose genetic sequences were becoming widely available as a result of breathtaking advances in sequencing techniques and informatics. An example is the rapid identification of H1N1 influenza as a potentially fatal pandemic illness and the rapid development and dissemination of an effective protective vaccine. Today, gene expression profiles are being used to guide therapy and inform prognosis for a number of diseases, the use of genotyping is providing a new means to assess the risk of certain diseases as well as variation in response to a number of drugs, and physicians are beginning to understand better the role of certain genes in the causality of common conditions such as obesity and allergies. Despite these advances, scientists are still in the infancy of understanding and utilizing the complexities of genomics in the diagnosis, prevention, and treatment of disease. The task of physicians is complicated by the fact that phenotypes generally are determined not by genes alone but by the interplay of genetic and environmental factors. Indeed, researchers have just begun to scratch the surface of possibilities that the era of genomics will provide to the practice of medicine. Rapid progress also is being made in other areas of molecular medicine. Epigenomics is the study of alterations in chromatin and histone proteins and methylation of DNA sequences that influence gene expression. Epigenetic alterations are associated with a number of cancers and other diseases. The study of the entire library of proteins made in a cell or organ and its relationship to disease is called proteomics. Proteomics is now recognized as far more complex than originally considered, enhancing the repertoire of the 30,000 genes in the human genome by alternate splicing and posttranslational processing as well as by an increasing number of posttranslational modifications, many with unique functional consequences. The presence or absence of particular proteins in the circulation or in cells is being explored for diagnostic and disease-screening uses. Microbiomics is the study of the bacterial flora of a person. Interesting research is suggesting that the composition of colonic flora may play a role in obesity and in other diseases. Metagenomics, of which microbiomics is a part, is the genomic study of environmental species that have the potential to influence human biology directly or indirectly. An example is the study of exposures to microorganisms in farm environments that might be responsible for the lower incidence of asthma among farm-raised children. Metabolomics is the study of the range of metabolites in cells or organs and the ways they are altered in disease states. The aging process itself may leave telltale metabolic footprints that allow the prediction (and possibly the prevention) of dysfunction and disease. It seems likely that disease-associated patterns will be sought in lipids, carbohydrates, membranes, mitochondria, and other vital components of cells and tissues. All this new information represents a challenge to the traditional reductionist approach to medical thinking. The variability of results in different patients, together with the large number of variables that can be assessed, creates difficulties in identifying preclinical disease and defining disease states unequivocally. Accordingly, the tools of systems biology are being applied to the myriad information now obtainable from every patient and may provide new approaches to classifying disease. For a more complete discussion of a complex systems approach to human disease, see Chap. e19. The rapidity of these advances may seem overwhelming to the practicing physician. However, he or she has an important role to play in ensuring that these powerful technologies and sources of new information are applied with sensitivity and intelligence to the patient. Since "omics" is such a rapidly evolving field, physicians and other health care professionals must continue to educate themselves so that they can apply this new knowledge to the benefit of their patients' health and well-being. Genetic testing requires wise counsel based on an understanding of the value and limitations of the tests as well as the implications of their results for specific individuals. For a more complete discussion of genetic testing, see Chap. 63. The Globalization of Medicine Physicians should be cognizant of diseases and health care services beyond local boundaries. Global travel has implications for disease spread, and it is not uncommon for diseases endemic to certain regions to be seen in other regions after a patient has traveled to and returned from those regions. Patients have broader access to unique expertise or clinical trials at distant medical centers, and the cost of travel may be offset by the quality of care at those distant locations. As much as any other factor influencing global aspects of medicine, the Internet has transformed the transfer of medical information throughout the world. This change has been accompanied by the transfer of technological skills through telemedicine and international consultation for radiologic images and pathologic specimens. For a complete discussion of global issues, see Chap. 2. Medicine on the Internet On the whole, the Internet has had a very positive effect on the practice of medicine; a wide range of information is available to physicians and patients through personal computers almost instantaneously at any time and from anywhere in the world. This medium holds enormous potential for delivering current information, practice guidelines, state-of-the-art conferences, journal contents, textbooks (including this text), and direct communications with other physicians and specialists, expanding the depth and breadth of information available to the physician about the diagnosis and care of patients. Medical journals are now accessible online, providing rapid sources of new information. This medium also serves to lessen the information gap felt by physicians and health care providers in remote areas by bringing them into direct and timely contact with the latest developments in medical care. Patients, too, are turning to the Internet in increasing numbers to acquire information about their illnesses and therapies and to join Internet-based support groups. Physicians increasingly are faced with the prospect of dealing with patients who arrive with sophisticated information about their illnesses. In this regard, physicians are challenged in a positive way to keep abreast of the latest relevant information while serving as an "editor" for the patients as they navigate this seemingly endless source of information, the accuracy and validity of which are not uniform. A critically important caveat is that virtually anything can be published on the Internet, with easy circumvention of the peer-review process that is an essential feature of academic publications. Physicians or patients who search the Internet for medical information must be aware of this danger. Notwithstanding this limitation, appropriate use of the Internet is revolutionizing information access for physicians and patients and in this regard is a great benefit that was not available to earlier practitioners. Public Expectations and Accountability The level of knowledge and sophistication regarding health issues on the part of the general public has grown rapidly over the last few decades. As a result, expectations of the health care system in general and of physicians in particular have risen. Physicians are expected to master rapidly advancing fields (the science of medicine) while considering their patients' unique needs (the art of medicine). Thus, physicians are held accountable not only for the technical aspects of the care that they provide but also for their patients' satisfaction with the delivery and costs of care. In many parts of the world, physicians increasingly are expected to account for the way in which they practice medicine by meeting certain standards prescribed by federal and local governments. The hospitalization of patients whose health care costs are reimbursed by the government and other third parties is subjected to utilization review. Thus, a physician must defend the cause for and duration of a patient's hospitalization if it falls outside certain "average" standards. Authorization for reimbursement increasingly is based on documentation of the nature and complexity of an illness, as reflected by recorded elements of the history and physical examination. There is a growing "pay for performance" movement that seeks to link reimbursement to quality of care. The goal of this movement is to improve standards of health care and contain spiraling health care costs. Physicians also are expected to give evidence of their continuing competence through mandatory continuing education, patient record audits, maintenance of certification, and relicensing. Medical Ethics and New Technologies The rapid pace of technological advances has profound implications for medical applications far beyond their traditional roles to prevent, treat, and cure disease. Cloning, genetic engineering, gene therapy, human-computer interfaces, nanotechnology, and designer drugs have the potential to modify inherited predispositions to disease, select desired characteristics in embryos, augment "normal" human performance, replace failing tissues, and substantially prolong life span. Because of their unique training, physicians have a responsibility to help shape the debate concerning the appropriate uses of and limits that should be placed on these new techniques. The Physician as Perpetual Student It becomes all too apparent from the time doctors graduate from medical school that as physicians their lot is that of the "perpetual student" and the mosaic of their knowledge and experiences is eternally unfinished. This concept can be at the same time exhilarating and anxiety-provoking. It is exhilarating because doctors will continue to expand knowledge that can be applied to their patients; it is anxiety-provoking because doctors realize that they will never know as much as they want or need to know. At best, doctors will translate this latter feeling into energy to continue to improve themselves and realize their potential as physicians. In this regard, it is the responsibility of a physician to pursue new knowledge continually by reading, attending conferences and courses, and consulting colleagues and the Internet. This is often a difficult task for a busy practitioner; however, such a commitment to continued learning is an integral part of being a physician and must be given the highest priority. The Physician as Citizen Being a physician is a privilege. The capacity to apply one's skills for the benefit of one's fellow human beings is a noble calling. The doctor-patient relationship is inherently unbalanced in the distribution of power. In light of a doctor's influence, he or she must always be aware of the potential impact of what he or she does and says and must always strive to strip away individual biases and preferences to find what is best for the patient. To the extent possible, a physician also should try to act within his or her community to promote health and alleviate suffering. Meeting these goals begins by setting a healthy example and continues in actions that may be taken to deliver needed care even when personal financial compensation may not be available. G. H. T. Kimble wrote: "It is bad enough that a [person] should be ignorant, for this cuts him [or her] off from the commerce of [people's] minds. It is perhaps worse that a [person] should be poor, for this condemns him [or her] to a life of stint and scheming in which there is no time for dreams and no respite from weariness. But what surely is worse is that a [person] should be unwell, for this prevents his [or her] doing anything much about either his [or her] poverty or his [or her] ignorance." A goal for medicine and its practitioners is to strive to provide the means by which the poor can cease to be unwell. Learning Medicine It has been about 100 years since the publication of the Flexner Report, a seminal study that transformed medical education and emphasized the scientific foundations of medicine as well as the acquisition of clinical skills. In an era of burgeoning information and access to medical simulation and informatics, many schools are implementing new curricula that emphasize lifelong learning and the acquisition of competencies in teamwork, communication skills, system-based practice, and professionalism. These and other features of the medical school curriculum provide the foundation for many of the themes highlighted in this chapter and are expected to allow physicians to progress from competency to proficiency to mastery with progressive experience and learning. At a time when the amount of information that one must master to practice medicine continues to expand, increasing pressures both within and outside of medicine have produced strict restrictions on the amount of time a physician in training can spend in the hospital. It was felt that the benefits associated with the continuity of medical care and observation of the patient's progress over time were outstripped by the stresses of long hours on the trainees and the fatigue-related errors they made in caring for patients. Accordingly, physicians in training had limits set on the number of patients they could carry at a time, the number of new patients they could evaluate in a day on call, and the number of hours they could spend in the hospital. In 1980, residents in medicine worked in the hospital more than 90 hours a week on average. In 1989, their hours were restricted to no more than 80 a week. Resident physicians' hours further decreased by about 10% between 1996 and 2008, and in 2010, the Accreditation Council for Graduate Medical Education (ACGME) placed further restrictions on continuing in-hospital duty hours for first year residents (16 hours/shift). The impact of these changes is continuing to be assessed, but the evidence that medical errors have decreased as a consequence is sparse. An unavoidable by-product of fewer hours at work is an increase in the number of "handoffs" of patient responsibility from one physician to another. These transfers often involve a transition from a physician who knows the patient well, having evaluated the patient on admission, to a physician who knows the patient less well. It is imperative that these transitions of responsibility be handled with care and thoroughness with all the relevant information exchanged and acknowledged. The issue of coverage is not limited to physicians in graduate training. The average practicing physician worked 54 hours per week in 1996–1998 and 51 hours per week in 2006–2008. Research, Teaching, and the Practice of Medicine The title doctor is derived from the Latin docere, "to teach," and physicians should share information and medical knowledge with colleagues, students of medicine and related professions, and their patients. The practice of medicine is dependent on the sum total of medical knowledge, which in turn is based on an unending chain of scientific discovery, clinical observation, analysis, and interpretation. Advances in medicine depend on the acquisition of new information through research, and improved medical care requires the transmission of that information. As part of broader societal responsibilities, the physician should encourage patients to participate in ethical and properly approved clinical investigations if they do not impose undue hazard, discomfort, or inconvenience. However, physicians engaged in clinical research must be alert to potential conflicts of interest between their research goals and their obligations to individual patients; the best interests of the patient must always take priority. To wrest from nature the secrets which have perplexed philosophers in all ages, to track to their sources the causes of disease, to correlate the vast stores of knowledge, that they may be quickly available for the prevention and cure of disease—these are our ambitions. —William Osler, 1849–1919