There are typically four distinct steps that a clinician takes to systematically solve most clinical problems:
1. Making the diagnosis
2. Assessing the severity or stage of the disease
3. Proposing a treatment based on the stage of the disease
4. Following the patient’s response to the treatment
MAKING THE DIAGNOSIS
A diagnosis is made by a careful evaluation of the database, analyzing the information, assessing the risk factors, and developing the list of possibilities (the differential diagnosis). Experience and knowledge help the physician “key in” on the most important possibilities. A good clinician also knows how to ask the same question in several different ways and use different terminology. For example, a patient may deny having been treated for “cholelithiasis” but answer affirmatively when asked if he has been hospitalized for “gallstones.” Reaching a diagnosis may be achieved by systematically reading about each possible cause and disease.
Usually a long list of possible diagnoses can be pared down to two or three that are the most likely, based on selective laboratory or imaging tests. For example, a patient who complains of upper abdominal pain and has a history of nonsteroidal anti-inflammatory drug use may have peptic ulcer disease; another patient who has abdominal pain, fatty food intolerance, and abdominal bloating may have cholelithiasis. Yet another individual with a 1-day history of periumbilical pain localizing to the right lower quadrant may have acute appendicitis.
The first step in clinical problem solving is making the diagnosis.
ASSESSING THE SEVERITY OF THE DISEASE
After establishing the diagnosis, the next step is to characterize the severity of the disease process, in other words, describing “how bad” a disease is. With malignancy, this is done formally by staging the cancer. Most cancers are categorized from stage I (least severe) to stage IV (most severe). With some diseases, such as with head trauma, there is a formal scale (the GCS) based on the patient’s eye-opening response, verbal response, and motor response.
The second step in clinical problem solving is to establish the severity or stage of the disease. There is usually prognostic or treatment significance based on the stage.
TREATING BASED ON THE STAGE
Many illnesses are stratified according to severity because the prognosis and treatment often vary based on the severity. If neither the prognosis nor the treatment were affected by the stage of the disease process, there would be no reason to subcategorize the illness as mild or severe. For example, obesity is subcategorized as moderate (body mass index [BMI] 35-40 kg/m2) or severe (BMI > 40 kg/m2), with different prognoses and recommended interventions. Surgical procedures for obesity such as gastric bypass are only generally considered when a patient has severe obesity and/or significant complications such as sleep apnea.
The third step in clinical problem solving is, in most cases, tailoring the treatment to the extent or stage of the disease.
FOLLOWING THE RESPONSE TO TREATMENT
The final step in the approach to disease is to follow the patient’s response to the therapy. The “measure” of response should be recorded and monitored. Some responses are clinical, such as improvement (or lack of improvement) in a patient’s abdominal pain, temperature, or pulmonary examination. Other responses can be followed by imaging tests such as a CT scan to determine the size of a retroperitoneal mass in a patient receiving chemotherapy, or with a tumor marker such as the level of prostate-specific antigen in a male receiving chemotherapy for prostatic cancer. For a closed-head injury, the GCS is used. The student must be prepared to know what to do if the measured marker does not respond according to what is expected. Is the next step to treat again, to reassess the diagnosis, to pursue a metastatic workup, or to follow up with another more specific test?
The fourth step in clinical problem solving is to monitor treatment response or efficacy, which can be measured in different ways. It may be symptomatic (the patient feels better) or based on a physical examination (fever), a laboratory test (prostate-specific antigen level), or an imaging test (size of a retroperitoneal lymph node on a CT scan).