uncontrolled observational study involving an intervention and
outcome for more than one person
(synonyms: anecdote, case history, single case report)
An uncontrolled observational study involving an intervention
and outcome for a single person.
(synonyms: case referent study, retrospective
A study that starts with identification of people with the
disease or outcome of interest (cases) and a suitable
control group without the disease or outcome. The relationship
of an attribute (intervention, exposure or risk
to the outcome of interest is examined by comparing the frequency
or level of the attribute in the cases and controls. For example,
to determine whether thalidomide caused birth defects
a group of children with birth defects (cases) could be compared
to a group of children without birth defects (controls).
The groups would then be compared with respect to the
proportion exposed to thalidomide through their mothers taking
the tablets. Case-control studies are sometimes described
as being retrospective
as they are always performed looking back in time.
(Compact Disc - Read Only Memory)
A computer storage medium. A CD-ROM can contain a database
of information (e.g. MEDLINE,
or the Cochrane
Controlled Trials Register)
that may be searched either on a personal computer or a computer
linked to a network.
Database of Systematic Reviews.
(Cumulative Index of Nursing and Allied Health Literature)
An electronic database covering the major journals in nursing
and allied health. Years of coverage: 1983 - present.
therapeutic trial, intervention study)
A trial that tests out a drug or other intervention to assess
its effectiveness and safety. This general term encompasses
international organization that aims to help people make well
informed decisions about health by preparing, maintaining and
ensuring the accessibility of systematic reviews of the
benefits and risks of healthcare interventions.
More information on the Cochrane Collaboration is available
from the Cochrane
Cochrane Controlled Trials Register
A database of references to controlled trials in health
care. Cochrane groups and other organizations have been invited
to contribute their specialized registers, and these registers,
together with references to clinical trials identified on MEDLINE,
form the CENTRAL register of studies. Records from CENTRAL,
following quality control to try to ensure that only reports
of definite randomized controlled trials or controlled clinical
trials are included, make up The Cochrane Controlled Trials
Cochrane Database of Systematic Reviews
The major product of the Cochrane Collaboration. It brings
together all the currently available Cochrane Reviews
and is updated quarterly. It also contains information about
the Collaboration. See Cochrane
A collection of databases, published on disk and CD-ROM
and updated quarterly, containing the Cochrane
Database of Systematic Reviews,
Controlled Trials Register,
of Abstracts of Reviews of Effectiveness,
the Cochrane Review Methodology Database, and information about
the Cochrane Collaboration.
(synonyms: follow-up, incidence, longitudinal, prospective
An observational study in which a defined group of people
(the cohort) is followed over time and outcomes are compared
in subsets of the cohort who were exposed or not exposed,
or exposed at different levels, to an intervention or other
factor of interest. Cohorts can be assembled in the present
and followed into the future (a "concurrent cohort study"),
or identified from past records and followed forward from that
time up to the present (a "historical cohort study").
Because random allocation is not used, matching or statistical
adjustment must be used to ensure that the comparison groups
are as similar as possible.
the application of additional diagnostic or therapeutic
procedures to members of either or both the experimental and
the control groups.
process used to prevent foreknowledge of group assignment in
which should be seen as distinct from blinding. The allocation
process should be impervious to any influence by the individual
making the allocation by having the randomization process administered
by someone who is not responsible for recruiting participants;
for example, a hospital pharmacy, or a central office. Using
methods of assignment such as date of birth and case record
numbers (see quasi-random
are open to manipulation. Adequate methods of allocation
concealment include: centralized randomization schemes; randomization
schemes controlled by a pharmacy; numbered or coded containers
in which capsules from identical-looking, numbered bottles are
administered sequentially; on-site computer systems, where allocations
are in a locked unreadable file; and sequentially numbered opaque,
summaries of presentations at conferences. May be published
The range within which the "true" values (e.g.
size of effect of an intervention) is expected to lie
with a given degree of certainty (e.g. 95% or 99%). Note: Confidence
intervals represent the probability of random
but not systematic errors (bias).
situation in which a measure of the effect of an intervention
or exposure is distorted because of the association of
exposure with other factor(s) that influence the outcome under
Someone, who uses, is affected by, or who is entitled or
compelled to use a health related service.
advocate or representative
who is actively involved with other consumers and able to represent
the perspectives and concerns of that broader group of people.
A consumer advocate, or representative, should be linked with
other consumers, accountable to them, and should not have a
conflict of interest in that role.
clinical trials, the inadvertent application of the intervention
being evaluated to people in the control group or inadvertent
failure to apply the intervention to people assigned to the
clinical trials comparing two or more interventions, a control
is a person in the comparison group that receives a placebo,
no intervention, usual care or another form of care.
a control is a person in the comparison group without
the disease or outcome of interest.
statistics control means to adjust for or take into account
extraneous influences or observations.
can also mean programs aimed at reducing or eliminating the
disease when applied to communicable (infectious) diseases.
Controlled clinical trial
Refers to a study that compares one or more intervention
groups to one or more comparison (control)
groups. Whilst not all controlled studies are randomized,
all randomized trials are controlled
economic analysis that converts effects into the same monetary
terms as the costs and compares them.
economic analysis that converts effects into health terms and
describes the costs for some additional health gain (e.g.
cost per additional stroke prevented).
economic analysis that converts effects into personal preferences
(or utilities) and describes how much it costs for some additional
quality gain (e.g. cost per additional quality-adjusted life-year).
process of assessing and interpreting evidence by systematically
considering its validity, results and relevance.
(synonym: prevalence study)
A study that examines the relationship between diseases
(or other health related characteristics) and other variables
of interest as they exist in a defined population at one particular
time. The temporal sequence of cause and effect cannot necessarily
be determined in a cross-sectional study.
type of clinical trial comparing two or more interventions in
which the participants, upon completion of the course
of one treatment are switched to another. For example, for a
comparison of treatments A and B, half the participants are
randomly allocated to receive them in the order A, B and half
to receive them in the order B, A. A problem with this
design is that the effects of the first treatment may carry
over into the period when the second is given.
database that provides access to the tables of contents and
bibliographic data from current issues of the world's leading
scholarly research journals in the sciences, social sciences,
arts and humanities. Over 6,600 journals covered.