Diagnosing Disease: The Process of Identifying the Causes of Illness - History Of A Patient's Health And Illness

Obtaining a complete and accurate medical history is the first step in the diagnostic process. In fact, many health care practitioners (physicians, nurses, and allied health professionals) believe that the patient's medical history is the key to diagnosis and that the physical examination and results of any diagnostic testing (laboratory analyses of blood or urine, x-rays, or other imaging studies) simply serve to confirm the diagnosis made on the basis of the medical history.

A medical history is developed using data collected during the health care practitioner's interview with the patient. The medical history also may include data from a health history form or health questionnaire completed by the patient before the visit with the practitioner. The objectives of taking a medical history are as follows:

• Obtain, develop, and document (create a written record) a clear, accurate, chronological account of the individual's medical history (including a family history, employment history, social history, and other relevant information) and current medical problems.
• List, describe, and assign priority to each symptom, complaint, and problem presented.
• Observe the patient's emotional state as reflected in voice, posture, and demeanor.
• Establish and enhance communication, trust, understanding, and comfort in the physician–patient (or nurse–patient) relationship

In addition to eliciting a history of all of the patient's previous medical problems and illnesses, the health care practitioner asks questions to learn about the history of the present illness or complaint—how and when it began, the nature of symptoms, aggravating and relieving factors, its effect on function, and any self-care measures the patient has taken.

The medical history also includes a review of physiological systems—such as the cardiovascular (related to heart and circulation), gastrointestinal (GI; digestive disorders), psychiatric (mental and emotional health), and neurologic systems (brain and nerve disorders)—through which the patient may experience symptoms of disease. The review of systems frequently helps the practitioner obtain information to help assess the severity of the present problem and confirm the diagnosis.

Because it relies on the patient's assessment of the severity, duration, and other characteristics of symptoms, as well as the patient's memories and interpretation of past illnesses, the medical history provides the practitioner with subjective information. Together with the objective findings of the physical examination and other diagnostic tests, it helps practitioners to identify disease correctly.