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The System
Dynamic Health Assessment tools - The DYNHA® System.
www.amIhealthy.com uses the
Dynamic Health Assessment (DYNHA®) System, a unique Internet application
that provides practical and precise measurement at the individual level. Drawing
on a pool of items from widely used health surveys-general and disease
specific-DYNHA® designs a brief assessment by asking only those questions
relevant to the individual's health state. By scoring all responses on a
standard metric, results can be compared for those who answer different
questions. The brevity of the assessment means that the DYNHA® System determines
scores on the "health ruler" at a fraction of the cost of traditional health
assessments. DYNHA® is the first system to provide results-in user-friendly,
real-time reports-that are precise enough for monitoring and managing the care
of individuals.
The advantage of dynamic assessments:
- Brevity of short form validity and precision of long form.
- Access to calibrated pool of items from the most widely used
health assessments.
- 80% to 90% reduction in time required completing health
assessments.
- Eliminates "ceiling" and "floor" effects.
- Comparability of scores across a variety of health assessment
tools.
- Increased precision of health status scores.
- User-friendly, real-time results with built-in interpretation
guidelines.
- Markedly reduced data collection costs.
The Science Behind DYNHA®
Modern psychometric methods [e.g., Item Response Theory (IRT), Rasch] are
statistical models of the relationship between a person's response on an item
and his/her score on a concept, or latent trait, being measured. Once a model
has been estimated for a pool of items, the model can be used to select items
for a specific purpose (e.g., development of a fixed-length short form;
development of a dynamic form).
In contrast to traditional psychometric methods that assume that measurement
error - the random variation in measurement - is constant across the various
levels of a given scale, Rasch and IRT models treat measurement precision as
varying over the score range. Thus, a specific estimate of the measurement error
can be given for each person at each scale level. According to Rasch and IRT,
measurement error is determined by the constellation of the item characteristics
(difficulty and discrimination parameters) answered by the respondent.
Basically, an item is most informative for people whose level of health is
closest to the difficulty of that item. Therefore, measurement precision may be
several times greater at levels of the ruler where many item thresholds are
lumped together compared to other parts of the scale.
The use of Rasch and IRT models enables the DYNHA® system to appropriately
estimate the level of measurement error around an individual's score. In
addition, the DYNHA® system has the capacity to use a computer algorithm that
will identify the optimal selection of items for a given individual's level of
health. The result is a more precise estimate of the individual's health score.
Furthermore, QualityMetric Incorporated DYNHA® system uses modern psychometric
methods to improve the accuracy of scoring for respondents with missing data.
Research to date has shown that estimation techniques based on Rasch and IRT
models are more precise than current estimation methods that rely on the simple
averaging of non-missing data and that a substantial proportion of those
currently lost due to missing data can be recovered. While current estimation
methods require an individual to have complete responses to at least one-half of
the questionnaire items in a particular scale, Rasch and IRT methods can
estimate a score with as little as one item response per scale. Consequently,
more data can be recovered with the use of Rasch and IRT methods than current
methods based on the sum-score approach.
Modern psychometric methods allow for tests to be individually tailored, or
adapted, for test respondents. Respondents can be ranked on the same continuum,
regardless of whether they have been presented any items in common during
assessment. In computer adaptive testing, a computer is used to administer a
tailored test (Wainer et al., 1990). Modern psychometric methods, then,
effectively complement the development of computer adaptive tests.
Drawing on a pool of items from widely used health surveys (general and
disease specific), DYNHA® designs a brief assessment by asking only those
questions relevant to the individual respondent's health state. By scoring all
responses on a standard metric, results can be compared for those who answer
different questions. The brevity of the assessment means that the DYNHA® system
determines the scores on the "health ruler" at a fraction of the cost of
traditional health assessments.
Item Pool Development
QualityMetric Incorporated item pools are developed though fielding of items
designed to assess general health, disease/condition impact and demographics.
Typically, the SF-8™ survey is presented first, followed by a set of
developmental disease/condition impact items and demographic items (items
selected from QM's Background Information Survey -- i.e., age, gender, chronic
disease condition checklist, global disease impact items). The developmental
impact assessment includes existing, modified and experimental items for
fielding. Existing items are selected from the most widely used survey
instruments for a given disease/condition. Each instrument is evaluated in terms
of item content, and approximately 20-30% of unmodified items are included in
the new item pool in order to anchor the new tool to existing instruments.
Modified items alter selected existing items to more closely approximate QM
standards for survey development. Experimental items are developed by QM
scientists. Empirical tests are conducted to examine the modified and
experimental items prior to inclusion in the final pool.
QualityMetric Incorporated latest initiative in item pool development is
comprised of five disease conditions (asthma, congestive heart failure,
rheumatoid arthritis, osteo arthritis, and rhinitis), as well as an assessment
of patient satisfaction, health risk and global disease impact for close to 30
disease conditions. Data for these conditions is being gathered by a
professional polling firm, Roper-Starch Worldwide.
Survey access is free for non-commercial use. The information
gathered on the site is kept confidential. Please read our Privacy
Statement for this web site.
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"Physicians who want to be competitive in the future will need to demonstrate
their accountability. Utilizing Internet technology in conducting patient
assessments is an incredibly powerful tool that physicians must harness
right away if they want to remain competitive. Or... patients will go elsewhere"
said David B. Nash, M.D., M.B.A., Associate Dean for Health Policy for
Jefferson Medical College in Philadelphia. |
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