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JAMAevidence Glossary

Terms are derived from Users' Guides to the Medical Literature: A Manual for Evidence-Based Practice, 2nd Edition, The Rational Clinical Examination: Evidence-Based Clinical Diagnosis and Care at the Close of Life: Evidence and Experience. Updated October 2014.
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S

Sampling error
Error introduced by chance differences between the estimate obtained from the sample and the true value in the population from which the sample was drawn. Sampling error is inherent in the use of sampling methods and is measured by the standard error.

Sanguineous exudate
Exudate, or fluid from a wound, that is bloody.

Schamroth sign
Normal fingers create a diamond-shaped window when the dorsal surfaces of the terminal phalanges of similar fingers are opposed. In the clubbed finger, the diamond becomes obliterated because of the loss of the profile angle and the increase in the soft tissue at the cuticle (Schamroth sign).

Screening
Services designed to detect people at high risk of experiencing a condition associated with a modifiable adverse outcome, offered to persons who have neither symptoms of nor risk factors for a target condition.

Secondary care
Medical care provided to a patient when referred by one health professional to another with more specialized qualifications or interests. There are two levels of referred care: secondary and tertiary. Secondary care is usually provided by a broadly skilled specialist such as a general surgeon, general internist or obstetrician. See also Referred care.

Secondary palliative care
Clinicians, services, and organizations that provide palliative care specialty consultation and care to terminally ill patients.

Secular trends
Changes in the probability of events with time, independent of known predictors of outcome.

Selective screening
Services to be offered to asymptomatic persons with one or more risk factors for a target condition, such as family history of the disease, certain personal behaviors, or membership in a population with increased prevalence of the disease. See also Screening.

Selective serotonin reuptake inhibitors (SSRIs)
A class of medications used as antidepressants and for other indications.

Self-awareness
A combination of self-knowledge and self-empathy and the development of dual-awareness, a stance that permits the clinician to simultaneously attend to and monitor the needs of the patient, the work environment, and his/her own subjective experience.

Self-care
Personal health maintenance.

Sensitivity
The proportion of people with a positive test result among those with the target condition. See also Sensitivity analysis; Specificity; SnNout.

Sensitivity analysis
Any test of the stability of the conclusions of a health care evaluation over a range of probability estimates, value judgments, and assumptions about the structure of the decisions to be made. This may involve the repeated evaluation of a decision model in which one or more of the parameters of interest are varied.

Sentinel effect
The tendency for human performance to improve when participants are aware that their behavior is being evaluated; in contrast to the Hawthorne effect, which refers to behavior change as a result of being observed but not evaluated.

Sequential sample
A sample in which all potentially eligible patients seen over a period of time are enrolled. See also Case series.

Sequential tests
Tests conducted in sequence, rather than simultaneously.

Serous exudate
A type of exudate, or fluid from a wound, that is low in protein content and cells. Typically watery and always clear in appearance.

Sialorrhea
Excessive saliva.

Sign
Any abnormality indicative of disease, discoverable by the clinician at an examination of the patient. It is an objective aspect of a disease.

Sign test
A nonparametric test for comparing two paired groups based on the relative ranking of values between the pairs.

Silo effect
One of the main reasons for considering narrower viewpoints in conducting an economic analysis is to assess the impact of change on the main budget holders because budgets may need to be adjusted before a new intervention can be adopted (the silo effect).

Similarity
A principle that all the trials are broadly similar with respect to populations, trial design, and outcomes. Used interchangeably with the more statistical term “exchangeability.”

Simple regression
Regression when there is only one independent variable under evaluation with respect to a dependent variable. See also Regression.

Simplified Acute Physiology Score (SAPS) II
A classification system used to measure the severity of illness for patients admitted to intensive care units. For more information, see Acute Physiology and Chronic Health Evaluation (APACHE) and the following article for the classification system: Le Gall JR, Lemeshow S, Saulnier F. A new Simplified Acute Physiology Score (SAPS II) based on a European/North American multicenter study. JAMA. 1993;270(24):2957-2963. Erratum in: JAMA 1994;271(17):1321. [PMID: 8254858]

Slitlamp examination
The slitlamp examination requires special equipment. The slitlamp beam is focused behind the crystalline lens into the anterior portion of the vitreous. Having the patient look up, then immediately down, then immediately straight ahead before focusing the light beam on the anterior vitreous improves visualization of vitreous hemorrhage or pigment.

SnNout
When a test with a high Sensitivity is Negative, it effectively rules out the diagnosis of disease. See also Sensitivity.

Snowball sampling
Study participants nominate or refer other potential study participants who meet the study inclusion criteria.

SNP
Abbreviation for single-nucleotide polymorphism, a single base pair change in the DNA sequence at a particular point compared with the “common” or “wild-type” sequence.

Social Dignity Inventory
Inventory of environmental or contextual influences that can affect a patient’s sense of dignity. (See also Chapter 27, Dignity-Conserving Care—A New Model for Palliative Care.)

Specificity
The proportion of people with a negative test result among those without the target condition. See also Sensitivity; SpPin.

Spectrum bias
Ideally, diagnostic test properties will be assessed in a population in which the spectrum of disease in the target-positive patients includes all those in whom clinicians might be uncertain about the diagnosis, and the target-negative patients include all those with conditions easily confused with the target condition. Spectrum bias may occur when the accuracy of a diagnostic test is assessed in a population that differs from this ideal. Examples of spectrum bias include a situation in which a substantial proportion of the target-positive population have advanced disease, and target-negative participants are normal or asymptomatic. Such situations typically occur in diagnostic case-control studies (eg, comparing those with advanced disease to normal individuals). Such studies are liable to yield an overly sanguine estimate of the usefulness of the test. See also Bias.

Speech disorders
Communication disorders in which normal speech is disrupted.

Spider nevi
Arterial lesions with a central red spot from which many small vessels radiate, resembling a spider's legs.

Spinal cord compression
A condition that develops when the spinal cord is compressed and constricted by bone fragments from a vertebral fracture, a tumor, abscess, ruptured intervertebral disk, or other lesion.

Spinal stenosis
Back pain caused by the spinal canal compressing the spinal cord. May include intervertebral disk bulging, ligamentum flavum hypertrophy, and facet joint osteorthritis.

SPIRIT
An acronym for spiritual history taking: S, spiritual belief system; P, personal spirituality; I, integration with a spiritual community; R, ritualized practices and restrictions; I, implications for medical care; T, terminal events planning.

Spirituality
Religious values or other beliefs meant to deepen one’s inner life or connectedness with a larger reality.

SpPin
When a test is highly Specific, a Positive result can rule in the diagnosis. See also Specificity.

Square wrist sign
The anteroposterior dimension of the wrist divided by the mediolateral dimension equals a ratio of greater than 0.70, when measured with calipers at the distal wrist crease.

St Gallen criteria
Since 1978, St Gallen conferences have developed consensus opinions for managing early breast cancer. These guidelines, classifying women with breast cancer as being at minimal/low, intermediate, and high risk, are recognized as the leading European treatment guidelines and in the United States are strongly supported by both the American Society of Clinical Oncology and the National Comprehensive Cancer Network. In particular, St Gallen Breast Cancer Guidelines provide recommendations for adjuvant systemic therapy.

Standard error
The standard deviation of an estimate of a population parameter. The standard error of the mean is the standard deviation of the estimate of the population mean value.

Standard gamble
A direct preference or utility measure that effectively asks respondents to rate their quality of life on a scale from 0 to 1.0, where 0 is death and 1.0 is full health. Respondents choose between a specified time x in their current health state and a gamble in which they have probability P (anywhere from 0 to 0.99) of full health for time x, and a probability 1 – P of immediate death.

Standards
Authoritative statements of minimal levels of acceptable performance or results, excellent levels of performance or results, or the range of acceptable performance or results.

STARI
Southern tick-associated rash illness (Masters disease).

Statistical inference
Statistical methodologies to make deductions about underlying truth. There are two principle functions: (1) To predict or estimate a population parameter from a sample statistic, and (2) to test statistically based hypotheses.

Statistical significance
A term indicating that the results obtained in an analysis of study data are unlikely to have occurred by chance, and the null hypothesis is rejected. When statistically significant, the probability of the observed results, given the null hypothesis, falls below a specified level of probability (most often P < 0.05).

Stereotactic radiosurgery
A treatment that focuses radiation to the shape of the tumor and results in minimal damage to surrounding tissue.

Stomach neoplasms
An abnormal mass of stomach tissue, including both benign gastric tumors (eg, MALTomas) and cancers.

Stopped early trials
Truncated randomized controlled trials (RCTs) are trials stopped early because of apparent harm because the investigators have concluded that they will not be able to demonstrate a treatment effect (futility), or because of apparent benefit. Believing the treatment from RCTs stopped early for benefit will be misleading if the decision to stop the trial resulted from catching the apparent benefit of treatment at a random high.

Stopping rules
These are methodological and statistical guides that inform decisions to stop trials early. They can incorporate issues such as the planned sample size, planned and conducted interim analyses, presence and type of data monitoring including independent research oversight, statistical boundaries, and statistical adjustments for interim analyses and stopping.

Stroke
A stroke occurs when the blood supply is unable to reach a part of the brain.

Stroke, hemorrhagic
A stroke that occurs from bleeding.

Stroke, ischemic
A stroke that occurs from impairment to blood flow by atherosclerosis or emboli.

Structured abstracts
These abstracts often include critical information about research conduct omitted from the original reports. They do not include the introduction or the discussion sections of the original report or the conclusions of the original study.

Study to Understand Prognoses and Preference for Outcomes and Risks of Treatment (SUPPORT)
A 1995 prospective cohort study of outcomes, preferences, and decision making in seriously ill hospitalized adults and their families. (See initial publication: SUPPORT Principal Investigators. A controlled trial to improve care for terminally ill hospitalized patients: the Study to Understand Prognoses and Preferences for Outcomes and Risks of Treatment (SUPPORT). JAMA. 1995;274:1591-1598.) [PMID: 7474243]

Subgroup analysis
The separate analysis of data for subgroups of patients, such as those at different stages of their illness, those with different comorbid conditions, or those of different ages.

Suicide, assisted
Synonym for physician-assisted suicide, the prescribing of lethal medications for patients to self-administer.

Supraventricular tachycardia
A rapid heart rate arrhythmia that originates in the atria.

Surrogate decision makers
Family members or others appointed to make decisions for the patient when he/she is unable to do so.

Surrogate outcomes or endpoints
Outcomes that are not in themselves important to patients but are associated with outcomes that are important to patients (eg, bone density for fracture, cholesterol for myocardial infarction, and blood pressure for stroke). These outcomes would not influence patient behavior if they were the only outcomes that would change with an intervention.

Survey
Observational study that focuses on obtaining information about activities, beliefs, preferences, knowledge, or attitudes from respondents through interviewer-administered or self-administered methods.

Survival analysis
A statistical procedure used to compare the proportion of patients in each group who experience an outcome or endpoint at various time intervals over the duration of the study (eg, death).

Survival curve
A curve that starts at 100% of the study population and shows the percentage of the population still surviving (or free of disease or some other outcome) at successive times for as long as information is available.

Survival rate
The percentage of people in a study or treatment group who are alive for a given period after diagnosis.

Symptom
Any phenomenon or departure from the normal in function, appearance, or sensation reported by the patient and suggestive or indicative of disease. Symptoms are considered subjective.

Syncope
Fainting; a temporary loss of consciousness, usually as a result of impaired blood flow to the brain.

Syndrome
A collection of signs and/or symptoms and/or physiological abnormalities.

Syndrome diagnosis
When no reference standards exist, investigators' degree of diagnostic certainty is much lower. In these situations, known sometimes as syndrome diagnosis, diagnostic criteria usually rely on a list of clinical features required for the diagnosis. See also Syndrome.

Synonymous SNP
A SNP that does not lead to a change in the amino acid sequence compared with the common or wild-type sequence. Compare to nonsynonymous, in which there is a change in the amino acid sequence as a result of the SNP.

Synovial fluid
Fluid found in the cavities of synovial joints.

Systematic review
1. The consolidation of research evidence that incorporates a critical assessment and evaluation of the research (not simply a summary) and addresses a focused clinical question using methods designed to reduce the likelihood of bias. 2. The identification, selection, appraisal, and summary of primary studies addressing a focused clinical question using methods to reduce the likelihood of bias.

Systemic inflammatory response syndrome (SIRS)
SIRS is a severe, whole-body reaction to an event such as trauma or infection. It is often a characteristic of sepsis and may be useful in determining the likelihood of bacteremia. See also Bacteremia.
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