There are generally four steps to the systematic solving of clinical problems:
1. Make the diagnosis
2. Assess the severity of the disease
3. Render a treatment based on the stage of the disease
4. Follow the response to the treatment
MAKING THE DIAGNOSIS
This is achieved with careful sifting of the database, analysis based on the risk factors present, and development of a list of possibilities (the differential diagnosis). The process includes knowing which pieces of information are more meaningful and which can be discarded. Experience and knowledge from reading help to guide the physician to key in on the most important concerns. A good clinician also knows how to ask the same question in several different ways and using different terminology, because patients at times will deny having been treated for asthma but will answer affirmatively to being hospitalized for wheezing. A diagnosis can be reached by systematically reviewing each possible cause and reading about each disease. The patient’s presentation is then matched up against each of these possibilities and either placed higher up on the list as a potential etiology or lower down because of the disease frequency, the patient’s presentation, or other clues. A patient’s risk factors may influence the probability of a diagnosis. Usually a long list of possible diagnoses can be pared down to two or three top suspicions, based on key laboratory or imaging tests. For example, an adolescent presenting with a fever as the chief complaint can have an extensive differential diagnosis reduced to far fewer possibilities when the history reveals an uncle in the home with cough, weight loss, and night sweats, and the physical examination shows an increased respiratory rate, lymphadenopathy, and right lower lobe lung crackles. In this case, the patient likely has tuberculosis.
ASSESSING THE SEVERITY OF THE DISEASE
The next step is to characterize the severity of the disease process. In asthma, this is done formally based on guidelines promulgated by the National Heart, Lung, and Blood Institute (NHLBI). Asthma categories range from mild intermittent (least severe) to severe persistent (most severe). For some conditions, such as syphilis, the staging depends on the length of time and follows along the natural history of the infection (ie, primary, secondary, or tertiary syphilis).
RENDERING TREATMENT BASED ON THE STAGE OF THE DISEASE
Many illnesses are stratified according to severity because prognosis and treatment vary based on the severity. If neither the prognosis nor the treatment was affected by the stage of the disease process, it would not make much sense to subcategorize something as mild or severe. As an example, mild intermittent asthma poses less danger than does severe persistent asthma (particularly if the patient has been intubated for asthma in the past). Accordingly, with mild intermittent asthma, the management would be intermittent short-acting β-agonist therapy while watching for any worsening of the disease into more serious categories (more severe disease). In contrast, a patient with severe persistent asthma would generally require short-acting β-agonist medications as well as long-acting β-agonists, inhaled steroids, and potentially oral steroids.
Group A β-hemolytic streptococcal pharyngeal infection (“strep throat”) is associated with complications including poststreptococcal glomerulonephritis and rheumatic fever. The presence of group A β-hemolytic streptococcus confers an increased risk of problems, but neither the prognosis nor the treatment is affected by “more” group A β-hemolytic streptococcus or “less” group A β-hemolytic streptococcus. Hence, the student should approach new disease by learning the mechanism, clinical presentation, how it is staged, and how the treatment varies based on stage.
FOLLOWING THE RESPONSE TO TREATMENT
The final step in the approach to disease is to follow the patient’s response to the therapy. Whatever the “measure” of response, it should be recorded and monitored. Some responses are clinical, such as a change in the patient’s pain level or temperature, or results of pulmonary examination. Obviously the student must work on being more skilled in eliciting the data in an unbiased and standardized manner. Other patients may be followed by imaging, such as computerized tomography (CT) scan of a retroperitoneal (RP) node size in a patient receiving chemotherapy for neuroblastoma, or a marker such as the platelet count in a patient recovering from Kawasaki syndrome. For syphilis, it may be the nonspecific treponemal antibody test rapid plasma reagin (RPR) titer every month. The student must know what to do if the measured marker does not respond according to the expected. Is the next step to treat further, or to repeat the metastatic workup, or to follow up with another more specific test?