Page 15 - 15Diarrhoeaandvomiting

Diarrhoea and vomiting caused by gastroenteritis in children under 5 years

Controlled clinical trial A clinical trial testing a specific drug or other treatment involving two (or more)
(CCT) groups of patients with the same disease. One (the experimental group) receives
the treatment that is being tested, and the other (the comparison or control
group) receives an alternative treatment, a placebo (dummy treatment) or no
treatment. The two groups are followed up to compare differences in outcomes
to see how effective the experimental treatment was. A CCT where patients are
randomly allocated to treatment and comparison groups is called a randomised
controlled trial.
Cost–benefit analysis A type of economic evaluation where both costs and benefits of healthcare
treatment are measured in the same monetary units. If benefits exceed costs, the
evaluation would recommend providing the treatment.
Cost-effectiveness Value for money. A specific healthcare treatment is said to be ‘cost-effective’ if
it gives a greater health gain than could be achieved by using the resources in
other ways.
Cost-effectiveness analysis A type of economic evaluation comparing the costs and the effects on health
of different treatments. Health effects are measured in ‘health-related units’, for
example, the cost of preventing one additional heart attack.
Cost–utility analysis A special form of cost-effectiveness analysis where health effects are measured
in quality-adjusted life years (QALYs). A treatment is assessed in terms of its
ability to both extend life and to improve the quality of life.
Crohn’s disease A form of chronic inflammatory bowel disease.
Cross-sectional study A type of observational study where information is collected from a defined set
of people at a single point in time or time period – a snapshot. (This type of study
contrasts with a longitudinal study, which follows the same set of people over a
period of time.)
Crystalloid fluids Substances that form a true solution and pass freely through a semi-permeable
membrane. They contain water and electrolytes and stay in the intravascular
compartment for a shorter time than colloids. Around 2–3 times more crystalloid
than colloid is needed to achieve an equivalent haemodynamic response.
Crystalloids are useful in maintaining fluid balance. The type of crystalloid given
as fluid maintenance needs to be tailored to the need of the patient and has to
take into account the daily requirement, insensible losses and measured losses
of fluid and electrolytes. Types of crystalloid include normal saline, dextrose 5%
and Hartmann’s solution (sodium lactate).
Cytotoxin A drug that damages or destroys cells.
Decision analysis Decision analysis is the study of how people make decisions or how they should
make decisions. There are several methods that decision analysts use to help
people to make better decisions, including decision trees.
Decision tree A decision tree is a method for helping people to make better decisions in
situations of uncertainty. It illustrates the decision as a succession of possible
actions and outcomes. It consists of the probabilities, costs and health
consequences associated with each option. The overall effectiveness or overall
cost-effectiveness of different actions can then be compared.
Declaration of interest A process by which members of a working group or committee ‘declare’ any
personal or professional involvement with a company (or related to a technology)
that might affect their objectivity, for example if their position or department is
funded by a pharmaceutical company.
Dehydration A state arising from loss of extracellular fluids and/or intracellular fluid.
Diagnostic study A study to assess the effectiveness of a test or measurement in terms of its ability
to accurately detect or exclude a specific disease, rather than to assess patient-
related outcomes. The accuracy of the test is compared with some method
(which is also known as the reference standard) of determining the true disease
status.
Dominance A term used in health economics describing when an option for treatment is
both less clinically effective and more costly than an alternative option. The less
effective and more costly option is said to be ‘dominated’.

xii