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Prognosis Vs. Diagnosis: Know the Differences

Prognosis Vs. Diagnosis
Prognosis and diagnosis are medical terms that tend to sound similar, however, are not. It is necessary to know what these terms mean in the medical field, in order to differentiate between the two. This post helps you with the same.
Praseeda Shirodkar
Last Updated: Apr 9, 2018
Did You Know?
There are numerical prognostic scoring systems for adults who are severely ill (or those in the intensive care unit), which are believed to give accurate information about how long the affected person might live. APACHE II scale is one such severity-of-disease classification system that is quite famous. This system is believed to be the most accurate when applied 7 days before the predicted death. This system is not allowed for use in children or those under 16 years of age.
Prognosis and diagnosis are terms used in the medical field. Many are aware of the term 'diagnosis'. The term 'prognosis' is relatively less known. It is often mistaken to be synonymous with 'diagnosis'. Thus, it becomes necessary to understand what these two terms mean. Both the terms 'prognosis' (pro meaning 'before' and gignoskein meaning 'come to know') and 'diagnosis' (dia meaning 'apart' and gignoskein meaning 'come to know') have originated from Greek words. Prognosis literally means 'foreknowing' and diagnosis means 'recognizing'.
Prognosis Vs. Diagnosis
Patient receiving MRI scan
In medical terms, diagnosis can be referred to as the detection or identification of a medical condition whereas prognosis is the course or probable outcome of the condition.
  • If the diagnosed medical condition in an affected person is common cold, then it would have a good prognosis i.e. the person would not have to suffer for long, as this condition is self-limiting.
  • If an individual is diagnosed with a condition such as last stage of breast cancer, the prognosis is the outcome or chance of recovery with the help of treatment in order to live longer.

Here is a detailed explanation of the two terms for a better understanding.
What is Diagnosis?
Doctor with x-ray plate
Diagnosis can be defined as a medical term for detecting the nature or cause of a medical condition. In other words, it is the conclusion that is made by the doctor about the medical condition that an individual is affected by.
➺ An affected person would have certain symptoms that the doctor uses, in order to identify the medical condition. On examining the person, the doctor may further decide whether additional tests are required. Then, the doctor names the condition. This explains diagnosis.

➺ The term 'diagnosis' is used in other fields such as logic and analytics as well.
What is Prognosis?
Doctor with senior patient
Prognosis can be defined as a medical term for predicting the course or probable outcome of an individual's medical condition. It includes the individual's recovery aspect and how the medical condition that he/she has been diagnosed with will progress.
➺ Once an individual is diagnosed with a medical condition (knowing its nature and cause), the appropriate treatment or a treatment program would be recommended. Further, the doctor would discuss what progression can be expected from this treatment. This would involve a description of the medical condition, the duration that is expected, whether complete recovery is expected with proper treatment, whether the condition will progress over time or not, how it will affect the individual, the complications it may lead to, etc. The whole discussion would mainly depend on the type of medical condition and its severity. That's because it would decide what impact the condition would have on one's lifestyle and the type of assistance required. Once the progression, duration, limitations, and other information is understood, a better decision for a treatment or care program can be made.

➺ Furthermore, the prognosis made is also said to depend on various factors such as the doctor's understanding of the condition, age of the affected individual, his/her physical condition, the success rate of a particular treatment, etc.

➺ The term prognosis can also be used to make predictive estimates for large statistical populations (in those diagnosed with a certain medical condition).
As much as early diagnosis of a medical condition is important for prompt treatment and complete recovery, knowing the prognosis helps to decide whether certain treatments are required or should be held back.