Prognosis (
Greek: πρόγνωσις "fore-knowing, foreseeing"; : prognoses) is a medical term for predicting the likelihood or expected development of a
disease
A disease is a particular abnormal condition that adversely affects the structure or function (biology), function of all or part of an organism and is not immediately due to any external injury. Diseases are often known to be medical condi ...
, including whether the
signs and symptoms will improve or worsen (and how quickly) or remain stable over time; expectations of
quality of life
Quality of life (QOL) is defined by the World Health Organization as "an individual's perception of their position in life in the context of the culture and value systems in which they live and in relation to their goals, expectations, standards ...
, such as the ability to carry out daily activities; the potential for complications and associated health issues; and the likelihood of survival (including life expectancy).
A prognosis is made on the basis of the normal course of the diagnosed disease, the individual's physical and mental condition, the available treatments, and additional factors.
A complete prognosis includes the expected duration, function, and description of the course of the disease, such as progressive decline, intermittent crisis, or sudden, unpredictable crisis.
When applied to large
statistical populations, prognostic estimates can be very accurate: for example the statement "45% of patients with severe
septic shock will
die within 28 days" can be made with some confidence, because previous research found that this proportion of patients died. This statistical information does not apply to the prognosis for each individual patient, because patient-specific factors can substantially change the expected course of the disease: additional information is needed to determine whether a patient belongs to the 45% who will die, or to the 55% who survive.
Methodology
Disease and prognostic indicators
Prognostic scoring is also used for cancer outcome predictions. A
Manchester score is an indicator of prognosis for small-cell lung cancer. For
Non-Hodgkin lymphoma, physicians have developed the
International Prognostic Index to predict patient outcome.
Other medical areas where prognostic indicators are used is in Drug-Induced Liver Injury (DILI) (
Hy's law) and use of an
exercise stress test as a prognostic indicator after
myocardial infarction
A myocardial infarction (MI), commonly known as a heart attack, occurs when Ischemia, blood flow decreases or stops in one of the coronary arteries of the heart, causing infarction (tissue death) to the heart muscle. The most common symptom ...
, also used to indicate
multiple myeloma survival rate.
End of life
Studies have found that most doctors are overly optimistic when making a prognosis; they tend to overstate how long a patient might live. For patients who are critically ill, particularly those in an
intensive care unit
An intensive care unit (ICU), also known as an intensive therapy unit or intensive treatment unit (ITU) or critical care unit (CCU), is a special department of a hospital or health care facility that provides intensive care medicine.
An inten ...
, there are numerical prognostic scoring systems that are more accurate. The most famous of these is the
APACHE II scale, which is most accurate when applied in the seven days prior to a patient's predicted death.
Knowing the prognosis helps determine whether it makes more sense to attempt certain treatments or to withhold them, and thus plays an important role in end-of-life decisions and
advanced care planning.
Estimator
Estimators that are commonly used to describe prognoses include:
*''
Progression-free survival'' - the length of time during and after medication or treatment during which the disease being treated (usually cancer) does not get worse.
*''
Survival rate'' – indicating the percentage of people in a study or treatment group who are alive for a given period of time after diagnosis.
*''Survival time'' – the remaining duration of life. If not otherwise specified, it generally starts from the time of diagnosis.
History
One of the earliest written works of medicine is the Book of Prognostics of
Hippocrates
Hippocrates of Kos (; ; ), also known as Hippocrates II, was a Greek physician and philosopher of the Classical Greece, classical period who is considered one of the most outstanding figures in the history of medicine. He is traditionally referr ...
, written around 400 BC. This work opens with the following statement: "It appears to me a most excellent thing for the physician to cultivate Prognosis; for by foreseeing and foretelling, in the presence of the sick, the present, the past, and the future, and explaining the omissions which patients have been guilty of, he will be the more readily believed to be acquainted with the circumstances of the sick; so that men will have confidence to intrust themselves to such a physician."
For 19th-century physicians, particularly those following the French school of medicine, the main aim of medicine was not to cure disease, but rather to give a medical diagnosis and achieve a satisfying ''prognosis'' of the patient's chances.
Only several decades later did the focus of efforts in Western medicine shift to curing disease.
See also
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References
External links
Computer models at prognosis.org
{{Authority control
Medical terminology