The document discusses several key issues regarding medical data: 1) Medicine lacks standardized vocabulary and terminology, creating problems for data retrieval and analysis across different observers and analysts. 2) Coding systems are used for health reporting but have limitations in clinical settings. Researchers developed the Unified Medical Language System (UMLS) to connect various vocabularies. 3) Physicians use a hypothetico-deductive approach in data collection and interpretation, generating hypotheses to guide sequential data collection and narrowing differential diagnoses.

1. The Structure of Medical
Data
• Medicine is remarkable for its failure to
develop a standarized vocabulary and
nomenclature
• Issues of data retrieval and analysis are
confounded by discrepancies between
observers and data analysts
• Imprecission and a lack of standarized
vocabulary are problematic when we wish to
aggregate data recorded by multiple health
professionals
• EHR’s, their encoding must be able to
presume a specific meaning for the terms

2. Coding systems
 Because of the needs to know about
health trends for populations and to
recognize epidemics in the early
stages, there are various health
reporting requirements for hospitals
and physicians.
 Also reporting discharge
diagnosis, procedures performed on
pacients
 The codes used must be well defined

3. Coding systems
 Coding systems have limitations when
are applied in more general clinical
settings
 Researchers have worked to develop
a unified medical language system
(UMLS), a common structure that ties
together the various vocabularies the
have been created

4. The Data Knowledge
Spectrum
 A central focus in medical informatics
is the information base that constitutes
the substance of medicine
 Three terms are frequently used to
describe the content of computed
based systems: data, information and
knowledge
 A database is a collection of individual
observations without summarizing
analysis

5. Strategies of Medical Data
Selection and Use
 All medical databases are basically
incomplete because they reflect the
selective collection of data by the
health care personnel
 The challenge is to ask only questions
that are necessary, to perform only the
examinations that are required and to
record only pertinent data

6. The Hypothetico - Deductive
Approach
 Studies of medical decision makers have
shown that strategies for data collection
and interpretation may be imbedded in
an interative process known as
hypothetico-deductive approach
 The central idea is one of
seuqential, staged data
collection, followed by data interpretation
and the generation of
hypotheses, leading to hipothesis-
directed selection of the next most
appropiate data to be collected.

7. The Hypothetico - Deductive
Approach
 Physicians refers to the set of active
hypothesis as the differential
diagnosis
 Physicians have developed safety
measures to avoid missing important
issues. They are focused in four
categories:
◦ Past medical history
◦ Family history
◦ Social history
◦ Review of systems

8. The Hypothetico - Deductive
Approach
 After finishing with the physical
examination the list of hipotheses may
be narrowed down sufficiently that the
physician can undertake specific
treatment
 It often is necessary to gather aditional
data
 The response of the patient to
treatment is itself a datum point that
may affect the hypotheses about a
patient’s illness

9. The relationship between data
and hypotheses
 Observation evokes a hypothesis
 Sensitivity: the likehood that a given
datum will be observed in a patient
with a given disease or condition
 Specificity. An observation is highly
specific for a disease if it is generally
not seen in patients who do not have
that disease

10. The relationship between data
and hypotheses
 The prevalence of a disease is simply
a measure of the frequency with which
the disease occurs in the population of
interest
 The predictive value of a test is simply
the post-test probability that a disease
is present based on the results of a
test

11. Methods for selecting questions
and comparing tests
 Given a set of current
hypotheses, how does the physician
decide what additional data should be
collected?

12. The Computer and Collection of
Medical Data
 The need for data entry by physicians
has posed a problem for medical
computing systems since the earliest
days of the field
 In some applications is possible for
data to be enterred automatically into
the computer
 The use of touch-
screens, mouse, PDA’s can help to
reduce the resistance to computer use