Difference Between Diagnosis and Prognosis

In the field of medicine, healthcare providers use different terms and jargons to communicate information about a patient's health status. Two of the most commonly used terms in medical practice are diagnosis and prognosis. Although these two terms might seem similar, they have different meanings and implications for patient care. Understanding the difference between diagnosis and prognosis is important for both patients and healthcare providers.

What is Diagnosis?

Diagnosis is the process of identifying a medical condition or disease by analyzing a patient's symptoms, medical history, and results from diagnostic tests. The goal of diagnosis is to determine the underlying cause of a patient's symptoms and to provide a label or name for the condition. A diagnosis can be made based on physical examination, laboratory tests, imaging studies, or a combination of these methods. Once a diagnosis is made, healthcare providers can develop a treatment plan tailored to the patient's needs.

For example, if a patient presents with a fever, cough, and chest pain, a healthcare provider might order a chest x-ray and blood tests to look for signs of pneumonia. If the results show evidence of bacterial infection, the healthcare provider might diagnose the patient with pneumonia and prescribe antibiotics to treat the infection.

What is Prognosis?

prognosis refers to the likely course and outcome of a disease or medical condition. Prognosis takes into account a patient's individual factors, such as age, sex, overall health status, and the severity of the disease. Healthcare providers use prognosis to help patients understand what they can expect in terms of their health outcomes and to make informed decisions about their care.

For example, if a patient is diagnosed with stage IV lung cancer, the healthcare provider might discuss the prognosis with the patient and their family. They might explain that the prognosis for stage IV lung cancer is generally poor, but that treatment options are available to improve quality of life and extend survival. The healthcare provider might also discuss the potential side effects of treatment and the patient's personal values and goals to develop a treatment plan that aligns with the patient's wishes.

A complete prognosis includes the expected duration, outcome, and description of the development of the disease (progressive improvement, progressive worsening, sudden, unpredictable crisis, etc.).

The prognoses are accurate for a large number of patients, but the statistical information is not enough when it comes to an individual patient. For example, if 70% of the patients recover fully after a certain disease, a specific prognosis is needed for every individual patient to determine whether she/he belongs to this 70% or not.

Differences: Diagnosis and Prognosis

The following table highlights the major differences between Diagnosis and Prognosis −





Diagnosis: Diagnosis is a medical term for the determination of the patient’s disease from its signs and symptoms.

Prognosis: Prognosis is a scientific prediction of the likely development of a disease and its outcome.


Diagnosis: The diagnosis is based on patient’s medical history, a clinical examination and if necessary – on special studies.

Prognosis: The prognosis is based on the knowledge of the typical course of a certain disease, the physical and mental state of the patient, the accompanying diseases (if any), the prescribed treatment, and other case- dependent factors.

Time frame

Diagnosis: The diagnosis concerns the current condition of the patient.

Prognosis: The prognosis concerns the future development of the patient’s condition.


In summary, diagnosis and prognosis are two important concepts in medicine that are often used interchangeably, but they have distinct meanings and implications for patient care. Diagnosis refers to the process of identifying a medical condition or disease, while prognosis refers to the likely course and outcome of the disease. Understanding the difference between diagnosis and prognosis is crucial for effective patient care, communication, and decision-making.

Updated on: 04-Apr-2023


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