Pressure Ulcer Prevention and Treatment Following Spinal Cord Injury - 2

2

PRESSURE ULCER PREVENTION AND TREATMENT FOLLOWING SPINAL CORD INJURY

recommendations and supporting rationales will
reflect the scientific literature review. Conversing
with other Panel Members is encouraged
regarding proposed recommendations as long as
individual recommendations are put forward to be
discussed in the larger Panel discussion. Panel
members are also responsible for providing any
rewrites/edits of their individual sections as
decided during full Panel discussions.

Rating the Scientific Evidence
The Methodology Team conducts a review of
the literature based on parameters developed by
the Panel for each CPG topic. The product of the
Methodology Team's literature review is a graded
list of relevant scientific publications that fall
within the established search parameters. PVA's
Research and Education Department is then
provided with the list of graded articles by the
Methodology Team.
Panel Members are not limited to the use
of the articles retrieved initially in the review
process. If Panel Members wish to use literature
that falls outside the search parameters, this
literature will be graded by the Methodology
Team and included in the CPG as deemed
appropriate by the Panel.
The Methodology Team begins its grading by
employing the hierarchy first discussed by Sackett
(1989) and later enhanced by Cook et al. (1992)
and the U.S. Preventive Health Services Task
Force (1996), presented in Table 1. Additionally,
each study is evaluated for internal and external
validity. Factors affecting internal validity (i.e.,
the extent to which the study provided valid
information about the individuals and conditions
studied) includes:


Randomization methods and comparability
of groups



Definition of interventions and/or exposures



Definition of outcome measures



Attrition rates



Confounding variables



Data collection methods and
observation bias



Methods of statistical analysis

Large randomized trials with clear-cut results
(and low risk of error)
II. Small randomized trials with uncertain results
(and moderate to high risk of error)
III. Nonrandomized trials with concurrent or
contemporaneous controls
IV Nonrandomized trials with historical controls
.
V Case series with no controls
.
Sources: Sackett, D.L. Rules of evidence and clinical recommendations on
the use of antithrombotic agents. Chest 95 (2 Suppl) (1989): 25-45; and
the U.S. Preventive Health Services Task Force. Guide to clinical preventive
services: An assessment of the effectiveness of 169 interventions.
Baltimore, MD: Williams and Wilkins, 1996.

These five levels of evidence do not directly
describe the quality or credibility of evidence.
Rather, they indicate the nature of the evidence
being used. Decisions must often be made in the
absence of published evidence. In these situations,
it is necessary to use the opinion of experts based
on their knowledge and clinical experience.
Rating of the evidence performed by
Methodology Team may change depending on
the best practices consistent with scientific
principles appropriate to each subject matter.

Grading the Recommendations
Each recommendation is graded according
to the level of scientific evidence supporting
it by the Panel. The framework used is outlined
in Table 2. These ratings represent the strength
of the supporting evidence cited in the rationale
for the recommendation, not the strength of
the recommendation itself

Selection of control groups, if any



I.

Selection bias and inclusion criteria



Levels of Scientific Evidence

Sample size and statistical power



through an examination of the characteristics of
the study population, the clinical setting and
environment, and the investigators and providers
of care. The resulting rankings, below, are
provided to the panel members during the
writing and deliberation process.

External validity (i.e., the extent to which
the study findings were generalized to conditions
other than the setting of the study) is evaluated

Table 1. Categories of the Strength of Evidence
Associated with the Recommendations
Category

A
B
C

Description

The guideline recommendation is supported by
one or more level I studies
The guideline recommendation is supported by
one or more level II studies
The guideline recommendation is supported
only by level III, IV, or V studies

Sources: Sackett, D.L. Rules of evidence and clinical recommendations on
the use of antithrombotic agents. Chest 95 (2 Suppl) (1989): 25-45; and
the U.S. Preventive Health Services Task Force. Guide to clinical preventive
services: An assessment of the effectiveness of 169 interventions.
Baltimore, MD: Williams and Wilkins, 1996.
Pressure Ulcer Prevention and Treatment Following Spinal Cord Injury

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