ESTABLISHING THE DIAGNOSIS

In some circumstances, the diagnosis (ie, an explanation for the patient’s symptoms and identification of other significant disease process) may be self-evident. When clinical data are more complex, the diagnosis may be established by
1. reviewing the patient’s history and physical, radiographic, and laboratory examination data;
2. listing those items that either clearly indicate an abnormality or that suggest the possibility of a significant health problem requiring further evaluation;
3. grouping these items into primary versus secondary symptoms, acute versus chronic problems, and high versus low priority for treatment; and

4. categorizing and labeling these grouped items according to a standardized system for the classification of disease.
The rapidity and accuracy with which a diagnosis or set of diagnoses can be achieved depends on the history and examination data that have been collected and on the clinician’s knowledge and ability to match these clinical data with a conceptual representation of one or more disease processes. In general, experienced clinicians have an extensive knowledge of human physiology and disease etiology, as well as recollections of past clinical experiences, and this enables them to establish the correct diagnosis fairly rapidly. Such “mental models” of disease syndromes also increase the efficiency with which experienced clinicians gather and evaluate clinical data and focus supplemental questioning and testing at all stages of the diagnostic process.
For effective treatment as well as for health insurance and medicolegal reasons, it is important that a diagnosis (or diagnostic summary) is entered into the patient’s record after the detailed history and physical, radiographic, and laboratory examination data. The patient (or a responsible family member or guardian) should also be informed of the diagnosis. When more than one health problem is identified, the diagnosis for the primary complaint (ie, the stated problem for which the patient sought medical or dental advice) is usually listed first, followed by subsidiary diagnoses of concurrent problems. Previously diagnosed conditions that remain as actual or potential problems are also included, with the qualification “by history,” “previously diagnosed,” or “treated” to indicate their status. Problems that were identified but not clearly diagnosed during the current evaluation can also be listed with the comment “to be ruled out.” Because oral medicine is concerned with regional problems that may or may not be modified by concurrent systemic disease, it is common for the list of diagnoses to include both oral lesions and systemic problems of actual or potential significance in the etiology or management of the oral lesion. Items in the medical history that do not relate to the current problem and that are not of major health significance usually are not included in the diagnostic summary. For example, a diagnosis might read as follows:
(i) Alveolar abscess, lower left first molar; (ii) Rampant dental caries secondary to radiation-induced salivary hypofunction; (iii) Carcinoma of tonsillar fossa, by history, excised and treated with 6.5 Gy 2 years ago; (iv) Cirrhosis and prolonged bleeding time, by history; (v) Hyperglycemia, R/O (rule out) diabetes.
A definite diagnosis cannot always be made, despite a careful review of all history, clinical, and laboratory data. In such cases, a descriptive term (rather than a formal diagnosis) may be used for the patient’s symptoms or lesion, with the added word “idiopathic,”“unexplained,” or (in the case of symptoms without apparent physical abnormality) “functional” or “symptomatic.” The clinician must decide what terminology to use in conversing with the patient and whether to clearly identify this diagnosis as “undetermined.” Irrespective of that decision, it is important to recognize the equivocal nature of the patient’s problem and to schedule additional evaluation, by referral to another consultant, additional testing, or placement of the patient on recall for follow-up studies.
Unfortunately, there is no generally accepted system for identifying and classifying diseases, and diagnoses are often written with concerns related to third-party reimbursement and to medicolegal and local peer review as well as for the purpose of accurate description and communication of the patient’s disease status.

Most practitioners probably follow the systems of disease classification and nomenclature that they were taught during their training since these usually serve as the framework for the mental models of disease syndromes on which they base their diagnoses.
Some standardization of diagnoses has been achieved in the United States as a result of the introduction (in the 1980s) of the diagnosis-related group (DRG) system as an obligatory cost-containment measure for the reimbursement of hospitals for inpatient care

and the more recent requirement that all requests for Medicare reimbursement for both inpatient and outpatient care include a diagnosis coded according to the lists contained in the International Classification of Diseases, 9th Revision, Clinical Modification (ICD-9-CM) codes, prepared under the auspices of the World Health Organization.

The DRG system

consists of 470 categories derived from multivariate analysis of data from a million hospitalized patients, including age, the patient’s International Classification of Diseases (ICD) diagnosis, surgical procedures, intrahospital complications, and length of hospital stay. Although scientifically derived, the DRG system is designed for fiscal use rather than as a system for the accurate classification of disease. It also emphasizes procedures rather than diseases and has a number of serious flaws in its classification and coding system.
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The ICD system, by contrast, was developed from attempts at establishing an internationally accepted list of causes of death and has undergone numerous revisions in the past 150 years, related to the various emphases placed on clinical, anatomic, biochemical, and perceived etiologic classification of disease at different times and different locations. There is still no official set of operational criteria for assigning the various diagnoses included in the ICD (even though many specialities

have attempted to match ICD codes with well-defined criteria for the differentiation of diseases affecting a given organ system), and codes are probably assigned in fairly arbitrary fashion in many circumstances. In addition, the categories for symptoms, lesions, and procedures applicable to disease of the oral cavity are limited and often outdated. Medicare and other thirdparty reimbursers are usually concerned only with diagnoses of those conditions that were actively diagnosed or treated at a given visit; concurrent problems not specifically addressed at that visit are omitted from the reimbursement diagnosis, even if they are of major health significance. The clinician, therefore, must address a number of concerns in formulating a diagnosis, selecting appropriate language for recording diagnoses on the chart and documenting requests for third-party reimbursement.
Patients must also be informed of their diagnoses as well as the results of the various examinations and tests carried out, they correlate with the patient’s signs and symptoms and they clearly establish that a particular diagnostic concern has not been confirmed. Because patients’ anxieties frequently emphasize the possibility of a potentially serious diagnosis, it is important to point out (when the facts allow) that the biopsy specimen revealed no evidence of a malignant growth, the blood test revealed no abnormality, and that no evidence of diseases such as diabetes, anemia, leukemia, or cancer was found. Equally important is the necessity to explain to the patient the nature, significance, and treatment of any lesion or disease that has been clearly diagnosed.