What is a Prognosis?

Prognosis is derived from Ancient Greek and can translate to foreseeing or foreknowledge. It can sometimes get confused with the word diagnosis, which means to give name to a person’s health condition or decide what ailments they suffer from. When a doctor gives a prognosis, they are typically using the best resources they have like clinical studies and previous experiences treating a disease to tell a patient what they can expect from an illness and the likelihood that they will survive the illness. A prognosis can help patients determine the types of care they should undertake to treat various illnesses.

A prognosis isn’t based solely on empirical scientific data. It’s really the doctor’s best guess, which may be guided in part by how other people have responded to the same illness. When a disease is rare or not frequently studied, determining survivability or outcome isn’t always possible. With fatal diseases, doctors may give ranges of possible dates by which they expect a patient not to be living, and there is some concern about prognoses when diseases might be but aren’t always fatal. If attitude makes a difference in recovery, you don’t want patients assuming they can’t survive a dangerous disease.

When a person receives a prognosis, it’s wise to remember that this is a best guess based on the previous experience or knowledge of the doctor. Like many prediction methods, it has an element of chance and doesn’t fully take into account the way any one person will respond to disease. On the other hand, certain common diseases, especially those that prove fatal may not be subject to that much guessing about eventual outcome.

Doctors do use some scientific tools to predict likelihood of death in people who are critically ill. One scale, the APACHE II scale, is fairly effective in predicting mortality, especially within a week of expected death. This scale may be used as a prognostic device to determine types of treatment that should be given or withheld, and to help inform family that death is likely or imminent.

Even with minor illnesses, a prognosis can prove helpful. A patient with strep throat may be told that their symptoms should resolve in a few days after starting antibiotic treatment. If symptoms persist beyond the point when the doctor predicted the patient would get better, this may indicate that different treatment is needed. When you receive small prognoses like these for small illnesses, it’s a good idea to understand when you expect to get better. This way, you can contact your doctor if treatment doesn’t appear to be working.

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Post 2
@Heavanet: I would say that your father-in-law should discuss the prognosis with his doctor, and perhaps together select a different antibiotic. It sounds like the prognosis, that he will start to feel better on his medication, is correct, but he just hasn't been prescribed the best antibiotic for his infection.
Post 1

Does anyone have any thoughts about how long into a course of antibiotics for a minor infection a patient should question if the treatment is working? My father-in-law is prescribed antibiotics for re-occurring sinus infections, but the prognosis never seems to fit the course of medication. His symptoms seem to linger, and the infection often returns.

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