Sim 2. Illness scripts
An illness script is an organized mental summary of your knowledge of a disease. It can be called up from memory almost instantaneously when you recognize a familiar pattern of signs and symptoms. Or it may take deliberate thought to find a script that matches a less familiar problem. When an illness script seems reasonably close to your patient’s presentation, that diagnosis is added to your differential.
Illness scripts are unique to individual clinicians, and most are built without conscious thought. You are already creating illness scripts for every disease you learn about, and you’ll add to it each time you diagnose a patient with that disease for the rest of your career.
Consciously comparing illness scripts can build your diagnostic skills more quickly. In this workshop, we’ll call on illness scripts for diagnoses that present with sore throat, using what you’ve learned in Infections & Immunity to practice thinking like a doctor!
Components of an illness script
The cognitive psychologists who first studied illness scripts identified three categories of information that most clinicians include:
- Fault: the pathophysiology that led to the illness.
- Predisposing conditions: the medical issues or social factors that promote or contribute to the disease
- Consequences: the typical signs and symptoms
Most clinicians also include management in their illness scripts. In FCM, we will focus on predisposing conditions and consequences, which we identify with the history and physical.
Problem representation to illness scripts
During the interview, an experienced physician compares their developing problem representation against illness scripts activated in their memories. Those that seem to ‘match’ become part of the differential diagnosis.
Imagine that you’re in your primary care clinic, about to see a previously healthy 15-year-old. The reason for the visit is listed as “2 days of sore throat and fever”. Your problem representation as you walk in the room is “healthy teenager with sore throat and fever”
Based on this limited information, diagnoses are probably already coming to mind. Strep throat is so common that pattern recognition may have activated this illness script right away.
| Diagnosis | Classical History | Epidemiology & pre | Classic exam findings |
|---|---|---|---|
| Strep throat | Sudden onset
Fever No cough nor rhinorrhea |
15% of adult cases
30% of pediatric cases Most common in 4-15 year-olds Uncommon > 45 unless exposed to kids |
T > 38
Tonsillar exudate Tender anterior cervical adenopathy May have palatal petechiae |
A pediatrician’s illness script for GAS pharyngitis would have much more detail, based on the hundreds of patients that they’ve seen. It would expand beyond the ‘classic’ findings to include less common presentations. Your illness scripts will be richer and more detailed for diseases that you see often.
In your blocks, you usually learn about diseases one at a time, but most patients present with a chief concern that suggests several possible diagnoses. Thinking about these diagnoses in parallel can help you develop your diagnostic reasoning skills. Next term, your FCM write-ups will include the illness scripts for 3 or 4 ‘most likely’ and ‘most lethal’ diagnoses on your differential in a table called a diagnoses matrix.
This matrix allows you to explicitly COMPARE and CONTRAST the different potential causes of your patient’s problem, identifying the history, risk factors and exam findings that might help you differentiate between them. We’ll practice using it in the sim!
| “Classic” History | Epidemiology & risk factors | Classic exam findings | |
|---|---|---|---|
| GABHS | Sudden onset
Fever No cough or rhinorrhea |
15% of adult cases
30% of pediatric cases Most common in 4-15 y.o. Uncommon in > 45 y.o. unless exposure to kids |
T > 38
Tonsillar exudate Tender anterior cervical adenopathy. May have palatal petechiae |
| Viral URI | Associated cold symptoms: nasal congestion, coryza, hoarseness, sinus discomfort, ear pain, or cough | 50% of adult cases | May have nasal congestion, conjunctivitis
Exam findings are typically minimal despite the patient feeling poorly. |
| Mono/EBV | Starts with malaise, headache, fever.
Significant fatigue Sore throat is the most prominent symptom. Other viruses can cause a mono-like syndrome, including acute HIV infection. |
Peak incidence is in the 15 to 24- year old range.
<2% of adult pharyngitis Mono-like syndrome can be caused by other viruses, such as acute HIV infection |
Tender cervical adenopathy.
May have splenomegaly and diffuse lymphadenopathy (peaks in the first week) May have palatal petechiae |
Resources & references