Illness Scripts
An illness script is an organized mental summary of a provider’s knowledge of a disease (1-3). It represents a clinician's knowledge about a particular disease, and may be as short as a 3x5 pocket card description for a rare disease, or as long as a book chapter for a commonly encountered illness. Classically, the components of a thorough illness script fall into three main categories: “the predisposing conditions, the pathophysiological insult, and the clinical consequences (4).” Within these categories, illness scripts often include a disease's pathophysiology, epidemiology, time course, salient symptoms and signs, diagnostics, and treatment. For example, a provider’s illness script for community acquired pneumonia (CAP) may include:
Synonym Meralgia Paraesthetica, Bernhardt-Roth syndrome
Epidemiology 3.4–4.3/10,000 person-years
Risk Factors Obesity, diabetes, pregnancy.
History Pain and/or dysaesthesia
Examination Sensory changes without motor findings.
Diagnosis Usually clinical
Tests Diagnostic injection, MRI.
DDX L2 or L3 radiculopathy, pelvic mass, superior gluteal nerve entrapment, hip joint pain, inguinal hernia, GTPS, femoral neuropathy.
Treatment Conservative management, injection.
With experience, providers hone their illness scripts in three important ways (5):
They encode a predictive value for each feature of the disease, enabling them to estimate the likelihood of a diagnosis when that feature is present or absent. Example: The absence of a fever does not exclude the diagnosis of community acquired pneumonia (CAP) in an elderly patient. They emphasize distinguishing characteristics whose presence or absence significantly alters the likelihood of the diagnosis, and helps differentiate it from another related diagnosis. Example: A lobar infiltrate on chest x-ray without cardiomegaly or cephalization of vessels is highly suggestive of CAP and makes congestive heart failure less likely. They develop a list of disease mimickers to consider when an illness script of a particular diagnosis is invoked.Example: Chronic obstructive pulmonary disease (COPD) exacerbation and congestive heart failure resemble CAP This iterative process continued throughout a clinician’s career, adds depth, precision and differentiating power to the foundational scripts developed during training (5). Diseases encountered less frequently will have less robust scripts.
