David L. Simel
OVERVIEWPhysicians have several specific medical goals that assume varying degrees of importance in encounters with patients, depending on their individual characteristics and the care setting. These goals include but are not limited to the translation of symptoms and signs into diagnoses, assessment of stability or change in known conditions, provision of information and counseling for future prevention, and reaffirmation or alteration of therapeutic interventions.In the context of these medical goals, the physician should also strive to address several related social goals whose achievement can synergistically improve medical outcomes, such as establishing a relationship and measure of trust. The interaction between the patient and physician represents not only a scientific encounter but also a social ritual centered on locus of control and meeting each other's expectations. Patients may not be able to express their needs fully and may fear loss of control in determining their own medical fate. Conversely, physicians also have expectations that they must consider and sometimes answer for themselves: a need to feel that they have not missed something important in addressing diagnostic challenges, a need to put limits on the time available for each interaction, and a need to maintain objectivity so that their evaluation and recommendations are not clouded by their emotional feelings about the patient. When the patient's needs are to establish the presence of health or the diagnosis for a symptom, the expertise of the physician is expressed through the performance and interpretation of a rational clinical examination.Physical Examination Begins with the HistoryIt is almost impossible to consider the history as distinct from the physical examination because the clinical examination begins as soon as the physician sees or hears the patient. Cynics contend that physical diagnostic skills have eroded because most diagnoses are made during the history and then confirmed by a more objective test, such as a laboratory value or a radiographic image. It is perhaps unfair to assume that clinical diagnostic skills have deteriorated because scientific principles were not applied to the clinical examination until the mid-1970s. Before then, the sparse literature that addressed the clinical examination was dominated by case reports and case series that provided anecdotal evidence in which the usefulness of the physical examination was often overstated. Even proponents of the clinical examination now demand proof of reasonable reproducibility and accuracy before they accept the value of specific components of the history and physical examination. No objective evidence supports the contention that physicians' diagnostic skills have deteriorated over time.Quantitative Principles of the Clinical ExaminationThe clinical examination can be studied with the same principles as those applied to more traditional tests, such as laboratory results or diagnostic images. For each component of the history and physical examination, there is an associated sensitivity (the percentage of patients with a disorder who have an abnormal finding), specificity (the percentage of patients without a disorder who have a normal finding), and measure of precision (the agreement beyond chance between two observers) (Chapter 9). Current research on the clinical examination uses likelihood ratios (LRs) that inform clinicians how likely they are to observe a particular finding in a patient with a given condition as opposed to a patient without the condition. When it is estimated that an older patient who “shuffles her feet” when she walks has an LR of 3.0 for Parkinson's disease (Chapter 433), it means her risk of Parkinson's disease increases threefold compared with the baseline risk. Similarly, if a patient who insists that he does not have “shaking in his arms” has an LR of 0.25 for Parkinson's disease, he is one fourth as likely (a reduced chance) compared with the baseline risk. Evaluation of the precision of the examination uses the kappa (K) statistic to describe the agreement beyond chance (0 = random agreement; + 1 = perfect agreement).How to Find Quantitative Information about the Clinical ExaminationFinding data on the sensitivity, specificity, LRs, and observer variability of components of the clinical examination may require a MEDLINE search for evaluation of a disease-specific condition (e.g., melanoma) or a clinical finding (e.g., splenomegaly) (Table 6-1).
TABLE 6-1 -- MEDLINE SEARCH STRATEGY FOR IDENTIFYING QUANTITATIVE INFORMATION ON THE CLINICAL EXAMINATION USING THE OVID SEARCH SYSTEM[*]
| * | OVID Technologies, Inc. A condition and a physical finding are given as examples. Abbreviations or search term abbreviations are as follows: “exp” indicates that the topic is “exploded” to include all subheadings for the topic. The “$” is a wildcard designator, so “exam$” would include the words examination, examining, and examiner. “mp” searches for the word or phrase in the title, abstract, registry number word, or mesh subject heading. Step 9 limits the search to studies that involve humans only and where the full manuscript is available online and is written in English. If the search yields too few topics, the limitation of full text available can be removed and the search repeated. If too many results are obtained, some of the items from step 8 can be eliminated. |
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