Osteoporosis is a highly heritable trait. Many candidate genes have been proposed as being involved in regulating bone mineral density (BMD). Few of these findings have been replicated in independent studies.

C-reactive protein (CRP) may help to refine global risk assessment for coronary heart disease (CHD), particularly among persons who are at intermediate risk on the basis of traditional risk factors alone.

Radiation therapy with charged particles can potentially deliver maximum doses while minimizing irradiation of surrounding tissues, and it may be more effective or less harmful than other forms of radiation therapy.

Computed tomography (CT), magnetic resonance imaging (MRI), and adrenal vein sampling (AVS) are used to distinguish unilateral from bilateral increased aldosterone secretion as a cause of primary aldosteronism. This distinction is crucial because unilateral primary aldosteronism can be treated surgically, whereas bilateral primary aldosteronism should be treated medically.

The rates of induction of labor and elective induction of labor are increasing. Whether elective induction of labor improves outcomes or simply leads to greater complications and health care costs is commonly debated in the literature.

Neuraminidase inhibitors (NAIs) are stockpiled internationally for extended use in an influenza pandemic.

Systematic reviews and meta-analyses are essential to summarize evidence relating to efficacy and safety of health care interventions accurately and reliably. The clarity and transparency of these reports, however, is not optimal. Poor reporting of systematic reviews diminishes their value to clinicians, policy makers, and other users. Since the development of the QUOROM (QUality Of Reporting Of Meta-analysis) Statement-a reporting guideline published in 1999-there have been several conceptual, methodological, and practical advances regarding the conduct and reporting of systematic reviews and meta-analyses. Also, reviews of published systematic reviews have found that key information about these studies is often poorly reported. Realizing these issues, an international group that included experienced authors and methodologists developed PRISMA (Preferred Reporting Items for Systematic reviews and Meta-Analyses) as an evolution of the original QUOROM guideline for systematic reviews and meta-analyses of evaluations of health care interventions. The PRISMA Statement consists of a 27-item checklist and a four-phase flow diagram. The checklist includes items deemed essential for transparent reporting of a systematic review. In this Explanation and Elaboration document, we explain the meaning and rationale for each checklist item. For each item, we include an example of good reporting and, where possible, references to relevant empirical studies and methodological literature. The PRISMA Statement, this document, and the associated Web site (www.prisma-statement.org) should be helpful resources to improve reporting of systematic reviews and meta-analyses.

Results from clinical trials examining the effect of intensive glucose control on cardiovascular disease have been conflicting.

Atrial fibrillation is the most common sustained arrhythmia. Medical treatment often fails to control symptoms.

Screening for hepatitis B virus (HBV) infection in pregnant women to identify newborns who will require prophylaxis against perinatal infection is a well-established, evidence-based standard of current medical practice. In 2004, the U.S. Preventive Services Task Force (USPSTF) recommended universal screening of pregnant women for HBV infection at the first prenatal visit.

Measures of low-density lipoprotein (LDL) subfractions have been proposed as an independent risk factor for cardiovascular disease.

The Centers for Medicare & Medicaid Services limit coverage of cancer drugs for off-label indications to indications listed in specified compendia.

Chronic hepatitis B infection can lead to liver failure, hepatocellular carcinoma, and death.

Despite advances in prevention and treatment, sexually transmitted infections (STIs) remain an important cause of morbidity and mortality in the United States.

The optimal duration of anticoagulation for a first episode of unprovoked venous thromboembolism (VTE) is uncertain. Methods for predicting risk for recurrence may identify low-risk patients who are less likely to benefit from prolonged anticoagulation.

In 2002, the U.S. Preventive Services Task Force (USPSTF) recommended colorectal cancer screening for adults 50 years of age or older but concluded that evidence was insufficient to prioritize among screening tests or evaluate newer tests, such as computed tomographic (CT) colonography.

Evidence comparing premixed insulin analogues (a mixture of rapid-acting and intermediate-acting insulin analogues) with other antidiabetic agents is urgently required to guide appropriate therapy.

Identifying previously undiagnosed cancer in patients with newly diagnosed venous thromboembolism (VTE) is important. Screening for malignant conditions can potentially diagnose more cases of cancer and at earlier stages, thereby preventing cancer-associated morbidity and perhaps mortality.

Seeding trials, clinical studies conducted by pharmaceutical companies that are designed to seem as if they answer a scientific question but primarily fulfill marketing objectives, have not been described in detail.

Despite the increasing prevalence of drug-resistant tuberculosis, most low- and middle-income countries use standardized regimens, without assessment of drug susceptibility.