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Abstract.  

Edward H. Livingston

in AMA Manual of Style: A Guide for Authors and Editors (11th edn)

Print Publication Year: 
Feb 2020
Published Online: 
Feb 2020
DOI: 
10.1093/jama/9780190246556.003.0019.022.0002
Item type: 
section
Many readers will read only the abstract of a research article, so it should include as precise a summary of the content as possible. In addition, because readers may decide to review the entire article based on information in the abstract, it should be well written and carefully constructed....

Case Series.  

Edward H. Livingston

in AMA Manual of Style: A Guide for Authors and Editors (11th edn)

Print Publication Year: 
Feb 2020
Published Online: 
Feb 2020
DOI: 
10.1093/jama/9780190246556.003.0019.022.0017
Item type: 
section
In a case series study, observations are made on a series of individuals, before and after they have received the same intervention, exposure, or diagnosis but have no control group. Case series describe characteristics of a group of patients or participants with a particular disease, disorder, signs, or symptoms or a group of patients or participants who have undergone a particular procedure or experienced a specific exposure or event. A case series may also examine larger units, such as groups of hospitals or municipalities. Case series can be useful to formulate a case definition of a disease or describe the experience of an individual or institution in treating a disease or performing a type of procedure. Case series should comprise consecutive patients or observations seen by the individual or institution to minimize ...

Case-Control Studies.  

Edward H. Livingston

in AMA Manual of Style: A Guide for Authors and Editors (11th edn)

Print Publication Year: 
Feb 2020
Published Online: 
Feb 2020
DOI: 
10.1093/jama/9780190246556.003.0019.022.0015
Item type: 
section
Case-control studies , which are always retrospective, compare those who have had an outcome or event ( cases ) with those who have not ( controls ). Cases and controls are then evaluated for exposure to various risk factors and thus should not be selected on the basis of their exposure to the risk factors under investigation. Cases and controls generally are matched according to specific characteristics (eg, age, sex, duration of disease) to reduce ...

Clinical Trials.  

Edward H. Livingston

in AMA Manual of Style: A Guide for Authors and Editors (11th edn)

Print Publication Year: 
Feb 2020
Published Online: 
Feb 2020
DOI: 
10.1093/jama/9780190246556.003.0019.021.0003
Item type: 
section
The International Committee of Medical Journal Editors (ICMJE) defines a clinical trial as “any research project that prospectively assigns human participants to intervention, with or without concurrent comparison or control groups, to study the relationship between a health-related intervention and a health outcome.”6 All clinical trials must be registered at an appropriate online public registry. Interventions include but are not limited to drugs, surgical procedures, devices, behavioral treatments, educational programs, dietary interventions, quality improvement interventions, process-of-care changes, and the like....

Cluster Trials.  

Edward H. Livingston

in AMA Manual of Style: A Guide for Authors and Editors (11th edn)

Print Publication Year: 
Feb 2020
Published Online: 
Feb 2020
DOI: 
10.1093/jama/9780190246556.003.0019.022.0011
Item type: 
section
Cluster randomization is undertaken when performance of the intervention risks contamination of the control group. Imagine a multifaceted intervention that involves sedation protocols and measures of arousal levels and readiness for weaning from a mechanical ventilator in a trial of extubation.25 In this scenario, intensive care unit (ICU) personnel performing these functions may be influenced by the effectiveness of the interventions and consciously or unconsciously use them on patients assigned to the control group. In cases such as this, it is best to perform the intervention in one ICU and apply the control intervention in a separate ICU. Instead of randomizing individual patients to intervention or control groups, ICUs are randomized. Each ICU is considered a cluster of patients....

Cohort Studies.  

Edward H. Livingston

in AMA Manual of Style: A Guide for Authors and Editors (11th edn)

Print Publication Year: 
Feb 2020
Published Online: 
Feb 2020
DOI: 
10.1093/jama/9780190246556.003.0019.022.0014
Item type: 
section
In a cohort study , a defined group of people (the cohort) is followed up over time to examine associations between different interventions and subsequent interventions. Cohort studies may be concurrent (prospective) or nonconcurrent (retrospective). A prospective cohort study follows up a group, or cohort , of individuals who are initially free of the outcome of interest. Individuals in a cohort generally share some underlying characteristic, such as age, sex, or exposure to a ...

Comparative Effectiveness Studies.  

Edward H. Livingston

in AMA Manual of Style: A Guide for Authors and Editors (11th edn)

Print Publication Year: 
Feb 2020
Published Online: 
Feb 2020
DOI: 
10.1093/jama/9780190246556.003.0019.022.0018
Item type: 
section
A comparative effectiveness study compares different interventions or strategies to prevent, diagnose, treat, and monitor health conditions to determine which work best for which patients and under what circumstances and which are associated with the greatest benefits and harms. Comparative effectiveness studies evaluate how effective existing therapies are in achieving various clinical outcomes. The outcomes may be tested by conducting RCTs or by observational analysis of existing data. Thus, from a study design perspective, they differ little from conventional studies of clinical efficacy....

Cross-sectional Studies.  

Edward H. Livingston

in AMA Manual of Style: A Guide for Authors and Editors (11th edn)

Print Publication Year: 
Feb 2020
Published Online: 
Feb 2020
DOI: 
10.1093/jama/9780190246556.003.0019.022.0016
Item type: 
section
Cross-sectional studies observe individuals at a single point or during a specific interval, in which exposure and outcome are ascertained simultaneously. Such studies may be helpful for suggesting associations among variables but cannot address whether one condition may precede or follow another. Thus, cross-sectional studies cannot establish ...

Crossover Trials.  

Edward H. Livingston

in AMA Manual of Style: A Guide for Authors and Editors (11th edn)

Print Publication Year: 
Feb 2020
Published Online: 
Feb 2020
DOI: 
10.1093/jama/9780190246556.003.0019.022.0009
Item type: 
section
In a crossover trial, participants receive more than 1 of the treatments under investigation, usually in a randomly determined sequence and with a prespecified amount of time (a washout period ) between sequential treatments. The participants and the investigators are generally blinded to the treatment assignment (double-blinded). This experimental design is often used for evaluating drug treatments. Each participant serves as his or her own control, thereby eliminating variability when comparing treatment effects and reducing the sample size needed to detect a statistically ...

Discussion.  

Edward H. Livingston

in AMA Manual of Style: A Guide for Authors and Editors (11th edn)

Print Publication Year: 
Feb 2020
Published Online: 
Feb 2020
DOI: 
10.1093/jama/9780190246556.003.0019.022.0006
Item type: 
section
Authors should address whether the hypothesis was supported or refuted by the study results or how the study question was answered. The study result should be placed in the context of published literature. The limitations of the study should be discussed, especially possible sources of ...

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