December 6 - 7, 2007 Advisory Committee Meeting
Overview and Update of CDC Literature Review
Dr. Haskell asked Bill Kohl, Ph.D., from CDC to provide an
overview of the CDC literature review database. Dr. Kohl indicated his
presentation was centered around two broad goals, one, to give a brief
background of the work CDC did leading up to the first Committee Meeting, and
two, highlight subsequent steps that have been taken following the first
The basic goals that guided CDC staff were to develop and
implement a feasible approach for systematic review of physical activity and
health literature and provide an initial literature database in preparation for
the initial Committee Meeting and finally supporting the Committee as they
developed recommendations. We developed a conceptual framework around which to
work, focusing on six basic physical activities, types of physical activity
exposures, intensity, frequency, duration, pattern and type and eight major
health outcomes: cardiovascular health, cardiovascular-respiratory health,
metabolic health, musculoskeletal health, cancers, functional health, mental
health, all-cause mortality and adverse events. It is important to note this
frame-work drove the development of the database which focused on health
outcomes and not all existing studies for risk factors and other predictors of
health outcomes. As a result of the discussion at the June meeting two
additional subcommittees were formed in addition to the existing eight health
outcomes, Youth and Energy Balance.
Following the June meeting, in anticipation of receiving
additional research requests from the Committee, CDC focused on four broad
What is the evidence that physical activities associated with
a particular outcome?
What is the evidence that the dose of physical activity is
associated with this outcome or its precursors?
What is the evidence that physical activity might increase the
risk of a certain outcome?
What is the evidence that an exposure of physical activity
other than 30 minutes a day is associated with the outcome?
Since the parameters of the initial literature search was 1996,
the date of the Surgeon General's report, through January 2007, the Committee
Chair requested additional searches through June 2007. Through this process an
additional 740 abstracts were reviewed and triaged, netting 100 additional
papers that were deemed relevant.
Additionally, CDC liaisons were identified to work with each
subcommittee on additional research needs. Six of the ten subcommittees
requested additional searches based on questions in the areas of cardiovascular
disease, metabolic health, musculoskeletal health, cancer adverse events and
youth, that were not asked during the initial search. This process added 1,444
abstracts, netting 266 papers deemed relevant. Twelve additional papers were
also added as they were missed in the initial review for miscellaneous reasons.
Finally, through the assistance of a librarian scientist 352
additional publications, research reports, meta-analysis, and review papers were
provided at the request of the Committee. The publications were not necessarily
abstracted as some were utilized as background information.
At the conclusion of Dr. Kohl's report, Dr. Haskell inquired
into the plans for the database after the Guideline process has been concluded.
Dr. Kohl responded that the database is a product of the federal government and
as such is available to the public. The database is currently a working
database; however, after the Committee's work has been completed further quality
control checks would be performed and more definite plans would be formulated
for making the database available to the public.