Importance of Medical History in Diagnosis

The medical history of a patient is the most useful and important element in making an accurate diagnosis, much more valuable than either physical examinations or diagnostic tests. 

'Listen to your patient they are telling you the diagnosis' is a much quoted aphorism

On Majority of occasions diagnosis is revealed in the patient's history.

The medical interview is the process of gathering data that will lead to an understanding of the disease and the underlying physiological process.

History taking is a skill which every Doctor has to learn, the basis of History taking is good communication between doctor and patient. The history is a sharing of experience between patient and doctor.

It is important for doctors to acquire good consultation skills which go beyond prescriptive history taking learned as part of the comprehensive and systematic clerking process outlined in textbooks. A good history is one which reveals the patient's ideas, concerns and expectations as well as any accompanying diagnosis. The doctor's agenda, incorporating lists of detailed questions, should not dominate the history taking. Listening is at the heart of good history taking. 

Often the history alone does reveal a diagnosis. Sometimes it is all that is required to make the diagnosis. A good example is with the complaint of headache where the diagnosis can be made from the description of the headache and perhaps some further questions. For example, in cluster headache the history is very characteristic and reveals the diagnosis without the need for examination or investigations.

A complete medical history consists of an account of: (1) the present illness; (2) past medical history; (3) family history; (4) occupational background; (5) psychosocial history; and (6) a review of body systems.

1.     An account of the present illness, which includes the circumstances surrounding the onset of recent health changes and the chronology of subsequent events that have led the patient to seek medical care, is essential to understanding the course of the disease process. Medications are listed in the medical history because they may play a role in the current illness.

2.     The past medical history is an overall view of the patient’s health prior to the present illness. It should include previous hospitalizations, injuries, operations, and any significant illness that may not have required hospitalization. Allergies are included here if not listed separately.

3.     Included in a family history are the age and state of health of each immediate family member as well as the cause of death of any parents, grandparents, and other close relatives. Of particular importance are genetic or environmental diseases that have known risks. If a close relative such as a father died of aheart attack (acute myocardial infarction) before age 60, all his children are at greater risk of suffering an early heart attack. This risk increases if other factors such as hypertension (high blood pressure) or elevated serum cholesterol are present. Similarly, a history of some cancers (e.g., colorectal cancer) increases the risk that offspring will develop that type of cancer. The development of lung cancer in a person provides even greater impetus for close relatives to avoid smoking. Examples of other diseases that may have hereditary roots are diabetes mellitus, schizophrenia and other forms of mental illness, and arthritis. In fact, any disease that arises in two or more members of a family suggests a possible predisposing factor, and the patient should be considered to be at increased risk for this condition.

4.     The occupational history is important because the workplace may be a source of toxins, such as chemicals, asbestos fibres, or cigarette smoke, that place one at higher risk of cancer or other diseases.

5.     The psychosocial history—information on education, lifestyle, marital status, and religious beliefs—may influence future medical decisions, as may the patient’s smoking history, alcohol intake, and use of controlled substances, such as marijuana or cocaine.

6.     The review of body systems allows the physician to identify any other symptoms that have not been noted previously and that may influence the patient’s current state of health or provide subtle clues to the diagnosis. All major body systems are reviewed in an orderly manner, usually from the head down to the extremities. The intent is to uncover any past illnesses or problems that have not been previously identified and that may now or later influence the patient’s health. For example, the patient may describe leg pain while walking, which could be an early indication of blood vessel occlusion and increase the physician’s concern about possible coronary artery disease that otherwise may not have been suspected.