The Diagnostic Process A BRIEF OVERVIEW

diagnostic process What is it? to figure out to problem solve method scheme

Define Problem Gather Evidence Form Hypothesis Test Hypothesis KNOWLEDGE

Define Problem Test Hypothesis Form Hypothesis Patient’s Complaint Gather Evidence History Physical Lab Differential Diagnosis Treatment MEDICAL KNOWLEDGE BASE

“The specific intervention (treatment) is less important to the [patient’s] outcome than the process of the interaction.”

The Science of Medicine Units of observation Quantities of measurement Instrument for obtaining measurement óSigns and symptoms óWords and sometimes numbers collecting the database:

Gathering Information Valid Reliable Discriminatory characteristics of good data:

Valid Appropriate to the problem

Reliable: Objective –free from misinterpretation based on bias or feeling Precise –represent the true data Reproducible –different observers obtain the same results

Sensitive : Sensitive : –able to pick-up or detect real disease Specific: Specific: Discriminatory: –able to rule-out disease in healthy people.

Gathering Information medical history physical examination diagnostic testing treatment outcome the clinical database:

Medical History: Validity Reliability  80% of diagnoses can be made by history alone  subjective nature of symptoms; subject to patient interpretation.  poor from patient to patient for a given condition  +/- for same patient on separate occasions

Physical Exam: Reliabiliy Validity  Objectivity -good; direct observation  Precision +/- ; open to interpretation  +/- some diseases are not detectable on physical exam.

Diagnostic Studies: Objective Validity  usually free from interpretation errors  some diseases do not produce measurable changes

The Science of Medicine Units of observation Quantities of measurement Instrument for obtaining measurement óSigns and symptoms óWords and sometimes numbers collecting the database: óYou

Clinician Characteristics Valid Reliable –Objective –Precise –Reproducible Discriminatory –Sensitive –Specific qualities of a useful measuring tool:

Valid  Appropriate to the problem  does the interviewer have a high enough index of suspicion to consider the possibility that a problem may exist

Objectivity: Removing one's own beliefs, prejudices, and preconceptions from observations. Precision: Using units of measurement (words) that are unambiguous and sufficiently detailed to indicate the real data.

Sensitivity: Sensitivity: ability to pick-up or detect real disease ability to rule-out disease in normal people. Specificity: Specificity: Discrimination:

Reliability: the ability to get the same result on repeated measures (reproducibility) the ability of different observers (interviewers) to get the same results.

“… interviewing skills that maximize objectivity and precision produce more accurate data and reduce the rate of false positive and false negative histories.”

One of the essential qualities of the clinician is interest in humanity, for the secret of the care of the patient is in caring for the patient. Francis Peabody 1923

More mistakes are made in medicine by people who don't care than by people who don't know. Allen Gregg