- caesarean section
Method of birth where the child is delivered through a cut made in the womb.
- candidiasis
A
disease caused by the fungi of the candida family such as Candida albicans.
Commonly known as thrush.
- capacity
In
discussions of consent for medical treatment, the ability of a person to make a
decision for themselves and understand its implications. Young children, people
who are unconscious and some people with mental health problems may lack
capacity.
- carcinoma
A malignant tumour that may spread throughout the body.
- cardiovascular
Relating to the heart and blood vessels.
- cardiovascular disease
Disease of the heart or blood vessels, such as heart attack and
stroke.
- case report
Describes
the medical history of a single patient.
- case-control study
An
observational study in which a group of people with an infection or condition
(called ‘cases’) are compared with a group of people without the infection or
condition (called ‘controls’). The past events and behaviour of the two groups
are compared. Case-control studies can help us understand the risk factors for
having an infection or a condition. However it is difficult both to accurately
collect information about past events and to eliminate bias from case-control
studies - see ‘confounding’.
- CAT scan
Computerised
axial tomography scan. A type of specialised X-ray that gives a view of a
'slice' through the body, and is used to help detect tumours, infections and
other changes in anatomy.
- catheter
A tube that is implanted with one end within the body and the other remaining outside, to make it easier to get drugs into, or waste products out of the body.
- CD4
A
molecule on the surface of some cells onto which HIV can bind. The CD4 cell
count roughly reflects the state of the immune system.
- CD8
A
molecule on the surface of some white blood cells. Some of these cells can kill
other cells that are infected with foreign organisms.
- central nervous system
The
brain and spinal cord.
- cerebral
Involving
the brain.
- cerebrospinal fluid (CSF)
The
liquid surrounding the brain and spinal cord.
- cerebrovascular
Involving the brain and the blood vessels supplying it.
- cervical intraepithelial neoplasia (CIN)
This means changes to the cervical tissue
which can be seen on visual examination through a colposcope. These are graded
CIN1 to 3 according to whether one-third, two-thirds or all of the normal cells
within the affected area are replaced by pre-cancerous ones. CIN1 is often left
untreated; higher-grade lesions will probably need removing.
- cervix
The neck of the womb, a tight ‘collar’ of tissue that closes off the womb except during childbirth.
Cancerous changes are most likely in the transformation zone where the vaginal
epithelium (lining) and the lining of the womb meet.
- chemotherapy
The
use of drugs to treat an illness, often denotes drugs used to treat cancer.
- chi-squared test
A statistical test used when comparing two proportions
(e.g. percentages with viral load below 50 copies/ml)
- cholesterol
A
waxy substance, mostly made by the body and used to produce steroid hormones.
High levels can be associated with atherosclerosis.
- chronic infection
When somebody has had
an infection for at least six months. See also ‘acute infection’.
- cirrhosis
Scarring of the liver – the structure of the liver is altered. See also
‘fibrosis’, which is moderate scarring. See also ‘compensated cirrhosis’ and
‘decompensated cirrhosis’.
- clinical
A
term referring to the nursing or medical care of patients.
- clinical event
The
occurrence of a physical sign or symptom, rather than an abnormality that can
only be detected by laboratory tests.
- clinical trial
A
research study involving participants, usually to find out how well a new drug
or treatment works in people and how safe it is.
- clinician
A
medical doctor who is active in looking after patients.
- CNS
Central
nervous system.
- codon
A position within a gene.
- cohort study
An
observational study in which a group of people (called a cohort) is followed
over a period of time and their medical history recorded. Cohort studies can
help us understand the risk factors for having an infection or a condition. Prospective
cohort studies (which track participants forward in time) are more reliable
than retrospective cohort studies. However it is difficult to eliminate bias
from cohort studies - see ‘confounding’.
- coinfection
Having
more than one infection at the same time. For example, when a person with HIV
has hepatitis B or C. This can make disease worse and treatment more difficult.
- colitis
Inflammation
of the bowels.
- colonoscopy
Examination of the large bowel using a video camera device.
- colposcopy
Examination of the surface of the cervix under magnification to identify the location and extent of abnormal lesions.
- combination therapy
Using more than one drug at a time.
- compassionate use
The release of an experimental drug by its manufacturer to people who are unable to obtain it in a clinical trial.
- compensated cirrhosis
The earlier stage of
cirrhosis, during which the liver is damaged but still able to perform most of
its functions. See also ‘cirrhosis’ and ‘decompensated cirrhosis’.
- complete early virological response (cEVR)
Hepatitis C RNA viral
load is undetectable by week 12 of treatment. See also ‘partial early
virological response (pEVR)’.
- compliance
An
alternative term for adherence.
- composite endpoint
An endpoint in a trial that includes several component parts; an individual is deemed to have met the criteria for the composite endpoint as soon as they meet the criteria for at least one of the components.
- concentration
The level of a drug
in the blood or other body fluid or tissue.
- confidence interval
A range of values that gives us an indication of how precise an estimate is - if the confidence interval is wide, the estimate is imprecise. The ‘true’ result could be as low or as high as the lower and upper values that are given. A 95% confidence interval suggests that there is a 95% probability that the true result is within the range given. Confidence intervals give similar information to p-values but are easier to interpret.
- confounding
Confounding
exists if the true association between one factor (Factor A) and an outcome is
obscured because there is a second factor (Factor B) which is associated with
both Factor A and the outcome. Confounding is often a problem in observational
studies when the characteristics of people in one group differ from the
characteristics of people in another group. When confounding factors are known
they can be measured and controlled for (see ‘multivariable analysis’), but
some confounding factors are likely to be unknown or unmeasured. This can lead
to biased results. Confounding is not usually a problem in randomised
controlled trials.
- consent
A patient’s agreement to take a test or a treatment. In medical ethics, an adult who has mental capacity always has the right to refuse. See also ‘capacity’ and ‘informed consent’.
- contagious
An
infection that can be spread easily, by casual contact.
- continuous endpoint
An
endpoint in a trial that captures a measurement which can have any value in a
range, e.g. CD4 count.
- contraindication
A
reason why a drug should not be used.
- control group
A
group of participants in a trial who receive standard treatment rather than the
experimental treatment which is being tested.
- coronary heart disease (CHD)
Occurs
when the walls of the coronary arteries become narrowed by a gradual fatty
build-up. Heart attack and angina are main symptoms.
- cost-effective
Cost-effectiveness analyses compare the financial cost of providing health interventions with their health benefit in order to assess whether interventions provide value for money. As well as the cost of providing medical care now, analyses may take into account savings on future health spending (because a person’s health has improved) and the economic contribution a healthy person could make to society.
- creatine kinase
An enzyme (a protein
that speeds up a chemical reaction) found mainly in the heart, brain, and
skeletal muscle. Raised levels can indicate there has been muscle damage.
- cross resistance
The
mechanism by which a virus that has developed resistance to one drug may also be
resistant to other, similar drugs.
- crossover trial
A
clinical trial where participants are switched from one arm to the other part
way through.
- cross-sectional study
A
‘snapshot’ study in which information is collected on people at one point in
time. See also ‘longitudinal’.
- cryoglobulinemia
Increased blood levels of a protein that can cause inflamed blood vessels
and thicken blood.
- cryptococcosis
A
type of fungal infection usually affecting the membrane around the brain,
causing meningitis. It can also affect the lungs and chest.
- cryptosporidiosis
Infection
with the gut parasite Cryptosporidium parvum and other species, causing
severe diarrhoea.
- culture
Laboratory
medium in which microbes can grow.
- cure
When the virus is no
longer present in the body. For hepatitis C, see ‘sustained virological
response’.
- cytokines
Chemical "messengers" exchanged between immune cells that affect the function of
the immune system. Interleukins such as IL-2 are a particular type of
cytokine.
- cytotoxic
Harmful
to cells.
- cytotoxic T-lymphocyte
A
type of white blood cell which kills virus-infected cells.