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Feverish illness in children
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NNT is to 1, the better the treatment is. Analogous to the NNT is the number
needed to harm (NNH), which is the number of patients that would need to
receive a treatment to cause one additional adverse event. For example, if the
NNH = 4, then four patients would have to be treated for one bad outcome to
occur.
Objective measure A measurement that follows a standardised procedure that is less open to
subjective interpretation by potentially biased observers and study participants.
Observation Observation is a research technique used to help understand complex
situations. It involves watching, listening to and recording behaviours, actions,
activities and interactions. The settings are usually natural, but they can be
laboratory settings, as in psychological research.
Observational study In research about diseases or treatments, this refers to a study in which nature
is allowed to take its course. Changes or differences in one characteristic (e.g.
whether or not people received a specific treatment or intervention) are studied
in relation to changes or differences in other(s) (e.g. whether or not they died),
without the intervention of the investigator. There is a greater risk of selection
bias than in experimental studies.
Odds ratio (OR) Odds are a way of representing probability, especially familiar for betting. In
recent years odds ratios have become widely used in reports of clinical studies.
They provide an estimate (usually with a confidence interval) for the effect of a
treatment. Odds are used to convey the idea of ‘risk’ and an odds ratio of 1
between two treatment groups would imply that the risks of an adverse
outcome were the same in each group. For rare events the odds ratio and the
relative risk (which uses actual risks and not odds) will be very similar. See also
relative risk, risk ratio.
Off-label prescribing When a drug or device is prescribed outside its specific indication, to treat a
condition or disease for which it is not specifically licensed.
Osteomyelitis Infection of bone and bone marrow. Osteomyelitis is usually caused by
bacteria. It can cause a chronic infection and disability if not treated
appropriately.
Outcome The end result of care and treatment and/or rehabilitation. In other words, the
change in health, functional ability, symptoms or situation of a person, which
can be used to measure the effectiveness of care/treatment/rehabilitation.
Researchers should decide what outcomes to measure before a study begins;
outcomes are then assessed at the end of the study.
P value If a study is done to compare two treatments then the P value is the probability
of obtaining the results of that study, or something more extreme, if there really
was no difference between treatments. (The assumption that there really is no
difference between treatments is called the ‘null hypothesis’.) Suppose the P
value was P = 0.03. What this means is that if there really was no difference
between treatments then there would only be a 3% chance of getting the kind
of results obtained. Since this chance seems quite low we should question the
validity of the assumption that there really is no difference between treatments.
We would conclude that there probably is a difference between treatments. By
convention, where the value of P is below 0.05 (i.e. less than 5%) the result is
seen as statistically significant. Where the value of P is 0.001 or less, the result
is seen as highly significant. P values just tell us whether an effect can be
regarded as statistically significant or not. In no way do they relate to how big
the effect might be, for which we need the confidence interval.
Paediatric specialist The term paediatric specialist refers to a healthcare professional who has had
specific training or has recognised expertise in the management of children and
their illnesses. Examples include paediatricians, or healthcare professionals
working in children’s emergency departments.