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The
Plan-Do-Study-Act Cycle
In
quality improvement projects, knowledge grows by repeating
the Plan-Do-Study-Act cycle on a small scale and by replicating
changes at other sites. Especially if the evidence supporting
a change is not strong, the change should be tested initially
on a small scale. This does not mean the change itself is
small. Small scale refers to the size of the test. The change
tested could be very innovative or a significant departure
from current practice, but is tried initially by only a
few physicians on a small subset of patients. The decision
to scale up to other physicians, patients, or settings is
based on the results of previous tests. The sequential approach
shown below contrasts to implementing the entire intervention
at once (Brock et al., 1998).
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5.2 Sequential Use of the PDSA Cycle
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Source:
Langley G, Nolan K, Nolan T, Norman C, Provost L. The
Improvement Guide: A Practical Approach to Enhancing Organizational
Perfromance. San Francisco, CA: Jossey-Bass; 1996:9.
Reprinted with permission from Associates in Process Improvement
(API).
This
approach is dynamic and fluid, which may unsettle investigators
accustomed to stating a fixed hypothesis and designing a
study to test the hypothesis. Despite this fluidity, investigators
must continue to insist that quality improvement teams make
as explicit as possible their current theories and hypotheses
(in flowchart form or some alternatively precise description
of the system).
In
the sequential testing of complex systems embodied by the
PDSA cycle, learning takes place at multiple levels. Data
may be collected for a short time in one or two PDSA cycles
to assist with the evolution of the system. For example,
the Tucson VA Hospital developed the time series pictured
below.
Figure
5.3 Percent of In-Patients with Pain Assessed
(Veterans Administration Hospital - Tucson, AZ)
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Source:
Southern Arizon VA Health Care System, Tucson, AZ. Reprinted
with permission from Anne Gooden, RN.
The
reliable assessment of pain for each patient was a component
of the pain management system they were testing and implementing
on two inpatient units. To monitor the percent of patients
who had their pain assessed, they randomly sampled the charts
of at least thirty patients from those two units each month.
After October 2000, a significant proportion of the patients
were being assessed. That component was now in place. Perhaps
only a small periodic audit is needed to assure that the
assessment remains reliable.
Learning
is also taking place at the system level. As components
are put in place-- for example pain assessment--the balanced
set of system measures provide feedback on whether the changes
result in improvement. As the system evolves, theories about
what will improve its performance can be focused and strengthened.
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