This statement summarizes the U.S. Preventive Services Task Force recommendations on hormone therapy for the prevention of chronic conditions in postmenopausal women and the supporting scientific evidence, and updates the Task Force's 2002 recommendations on hormone replacement therapy. The updated statement is based on the results of the Women's Health Initiative randomized, controlled trial, as well as the information in the 2002 summary of the evidence on this topic, which is available on the USPSTF Web site (http://www.preventiveservices.ahrq.gov).

The United States has the most expensive health care system in the world, with per capita health expenditures far above those of any other nation. For many years, U.S. health care expenditures have been growing above the overall rate of inflation in the economy. A few experts have argued that high and rising costs are not such a serious problem. Most observers disagree with this view, pointing to the negative impact of employee health care costs on employers, the government budgetary problems caused by rising health care expenditures, and an association between high health care costs and reduced access for individuals needing health services. Several explanations have been offered for high and rising health care costs. These include the perspectives that high and rising costs are created by forces external to the health system, by the weakness of a competitive free market within the health system, by the rapid diffusion of new technologies, by excessive costs of administering the health system, by the absence of strong cost-containment measures, and by undue market power of health care providers. This article, the first in a 4-part series, discusses 3 perspectives on health care: 1) Are high and rising health care costs a serious problem? 2) Are rising costs explained by factors outside the health care system? 3) Does the absence of a free market in health care explain why costs are high and rising? The remaining 3 articles in this series address other perspectives on health care costs.

Microscopic diagnosis of malaria is unreliable outside specialized centers. Rapid tests have become available in recent years, but their accuracy has not been assessed systematically.

Current guidelines for the diagnosis of non-ST-segment elevation myocardial infarction are largely based on an elevated troponin level. While this rapid and sensitive blood test is certainly valuable in the appropriate setting, its widespread use in a variety of clinical scenarios may lead to the detection of troponin elevation in the absence of thrombotic acute coronary syndromes. Many diseases, such as sepsis, hypovolemia, atrial fibrillation, congestive heart failure, pulmonary embolism, myocarditis, myocardial contusion, and renal failure, can be associated with an increase in troponin level. These elevations may arise from various causes other than thrombotic coronary artery occlusion. Given the lack of any supportive data at present, patients with nonthrombotic troponin elevation should not be treated with antithrombotic and antiplatelet agents. Rather, the underlying cause of the troponin elevation should be targeted. However, troponin elevation in the absence of thrombotic acute coronary syndromes still retains prognostic value. Thus, cardiac troponin elevations are common in numerous disease states and do not necessarily indicate the presence of a thrombotic acute coronary syndrome. While troponin is a sensitive biomarker to "rule out" non-ST-segment elevation myocardial infarction, it is less useful to "rule in" this event because it may lack specificity for acute coronary syndromes.

Exercise therapy encompasses a heterogeneous group of interventions. There continues to be uncertainty about the most effective exercise approach in chronic low back pain.

Exercise therapy is widely used as an intervention in low back pain.

Coordinated care is a defining principle of primary care, but it is becoming increasingly difficult to provide as the health care delivery system in the United States becomes more complex. To guide recommendations for research and practice, the evidence about implementation of coordinated care and its benefits must be considered. On the basis of review of the published literature this article makes recommendations concerning needs for a better-developed evidence base to substantiate the value of care coordination, generalist practices to be the hub of care coordination for most patients, improved communication among clinicians, a team approach to achieve coordination, integration of patients and families as partners, and incorporation of medical informatics. Although coordination of care is central to generalist practice, it requires far more effort than physicians alone can deliver. To make policy recommendations, further work is needed to identify essential elements of care coordination and prove its effectiveness at improving health outcomes.

Low back pain limits activity and is the second most frequent reason for physician visits. Previous research shows widespread use of acupuncture for low back pain.

Computed tomographic (CT) colonography, also called virtual colonoscopy, is an evolving technology under evaluation as a new method of screening for colorectal cancer. However, its performance as a test has varied widely across studies, and the reasons for these discrepancies are poorly defined.

Controversy exists regarding the effectiveness of surgery for weight loss and the resulting improvement in health-related outcomes.

In response to the increase in obesity, pharmacologic treatments for weight loss have become more numerous and more commonly used.

This guideline is based on the evidence report and accompanying background papers developed by the Southern California Evidence-Based Practice Center. The American College of Physicians nominated this topic to the Agency for Healthcare Research and Quality Evidence-Based Practice Center program as part of a concerted effort to complement the guidelines of the U.S. Preventive Services Task Force. The College recommends that all clinicians refer to the Task Force recommendations as part of an overall strategy for managing overweight and obesity, which should always include appropriate diet and exercise for all patients who are overweight or obese. The intent of this guideline is to provide recommendations based on a review of the evidence on pharmacologic and surgical treatments of obesity. The target audience is all clinicians caring for obese patients, defined as a body mass index of 30 kg/m2 or greater. This guideline is not intended to be used by commercial weight loss centers or for direct-to-consumer marketing by manufacturers and does not apply to patients with body mass indices below 30 kg/m2.

Surveys have documented the continued popularity of low-dose dopamine to influence renal dysfunction even though few data support it and editorials and reviews have discouraged its use.

No consensus exists on the best methods for diagnosis of intravascular device (IVD)-related bloodstream infection.

The acute porphyrias, 4 inherited disorders of heme biosynthesis, cause life-threatening attacks of neurovisceral symptoms that mimic many other acute medical and psychiatric conditions. Lack of clinical recognition often delays effective treatment, and inappropriate diagnostic tests may lead to misdiagnosis and inappropriate treatment. We review the clinical manifestations, pathophysiology, and genetics of the acute porphyrias and provide recommendations for diagnosis and treatment on the basis of reviews of the literature and clinical experience. An acute porphyria should be considered in many patients with unexplained abdominal pain or other characteristic symptoms. The diagnosis can be rapidly confirmed by demonstration of a markedly increased urinary porphobilinogen level by using a single-void urine specimen. This specimen should also be saved for quantitative measurement of porphobilinogen, 5-aminolevulinic acid, and total porphyrin levels. Intravenous hemin therapy, started as soon as possible, is the most effective treatment. Intravenous glucose alone is appropriate only for mild attacks (mild pain, no paresis or hyponatremia) or until hemin is available. Precipitating factors should be eliminated, and appropriate supportive and symptomatic therapy should be initiated. Prompt diagnosis and treatment greatly improve prognosis and may prevent development of severe or chronic neuropathic symptoms. We recommend identification of at-risk relatives through enzymatic or gene studies.

Aspirin is currently the most cost-effective drug for the secondary prevention of cardiovascular disease, but treatment failures are relatively common. Several factors have been linked to these recurrent vascular events in patients prescribed aspirin, including smoking, drug interactions, nonadherence, comorbid conditions, and aspirin resistance. The term aspirin resistance has been used to describe not only an absence of the expected pharmacologic effects of aspirin on platelets but also poor clinical outcomes, such as recurrent vascular events, in patients treated with aspirin. Aspirin resistance is perhaps more precisely understood as the phenomenon of measurable, persisting platelet activation that occurs in patients prescribed a therapeutic dose of aspirin and may underlie an unknown proportion of aspirin treatment failures. Key challenges for future research are to standardize a definition of aspirin resistance and to compare whether different measures of platelet activation, either alone or in combination, independently predict cardiovascular events. These challenges must be met before researchers conduct studies to assess the clinical utility of testing on patient outcomes and cost-effective prescribing.

Giant-cell arteritis is a diagnostic challenge.

Celiac disease is a common autoimmune disorder that has genetic, environmental, and immunologic components. It is characterized by an immune response to ingested wheat gluten and related proteins of rye and barley that leads to inflammation, villous atrophy, and crypt hyperplasia in the intestine. The disease is closely associated with genes that code for human leukocyte antigens DQ2 and DQ8. Transglutaminase 2 appears to be an important component of the disease, both as a deamidating enzyme that can enhance the immunostimulatory effect of gluten and as a target autoantigen in the immune response. Sensitive and specific serologic tests, including those for anti-transglutaminase antibody, are facilitating fast and noninvasive screening for celiac disease. Thus, they are contributing to a more accurate estimate of the prevalence of the disease and its association with other disorders. Celiac disease is associated with increased rates of anemia, osteoporosis, cancer, neurologic deficits, and additional autoimmune disorders. A gluten-free diet is the mainstay of safe and effective treatment of celiac disease, although its effect on some of the extraintestinal manifestations of the disease remains to be determined.