June 28 - 29, 2007 Advisory Committee Meeting
Review of Timeline, Milestones, and Process
Dr. Haskell reviewed the overall timeline for the Committee indicating
tentative Committee Meetings scheduled for December 2007 and February 2008. In
order to support the work of the Committee, Dr. Kohl and a team at CDC
instituted an extensive and comprehensive process of reviewing and abstracting
key scientific literature on physical activity and health in early 2007. The
Committee, from now until December, will review, interpret and prepare
preliminary reports based on best science. Between November 2007 and February
2008 the Committee will continue to address key issues raised by Committee
Members with the goal of producing a written report by February 2008. HHS in
turn has a tentative goal of producing Guidelines no later than October 2008.
Dr. Haskell then stated the next step for the Committee would be to organize
into sub-committees; however, the Committee as a whole should agree with this
process. Committee members would chair the sub-committees and be free to recruit
additional experts outside of the Committee to provide assistance and input. CDC
will provide each sub-committee assistance should additional literature be
required. HHS in turn will provide additional administrative support as needed.
Dr. Haskell noted that he, Dr. Nelson and Dr. Kohl would serve as a working
group to facilitate requests from the Committee to CDC.
Dr. Haskell noted throughout the agenda of this meeting Committee Members
will be addressing topics based on health outcomes. He raised the question
whether the Committee's work should be based on health outcomes? Part of the
rationale for organizing in this manner is that most studies are outcome
oriented, many physical activity scientists are structured by disease outcomes
and the initial literature review conducted by CDC is organized by disease
outcomes. The Committee would start reviewing and interpreting the literature
and write statements about the relationship between physical activity and
specific outcomes. Major challenges for the Committee include determining how to
get the scientific review completed and presenting the interpretation of the
science in a manner that HHS can utilize to develop policies.
CAPT Troiano commented that work performed by sub-committees must also
eventually be presented and approved by the full Committee, allowing the general
public to observe and comment, due to the fact the Committee is operating under
the Federal Advisory Committee Act. Sub-committee members should be thought of
as consultative members that will assist the Committee through their expertise
in a particular field. There is no specific process for recruiting sub-committee
members and staff will make sure they are properly credited for work performed.
Several Committee Members commented on the issue of organizing work around
health outcomes since the interpretation of the science will eventually have to
deal with exposures and specific sub-groups. Concern was expressed over the
relative limited time available to produce the report which is why basing
initial work of the Committee around health outcomes will allow for a more rapid
review of the literature. It was noted while conducting the literature review it
may be possible and beneficial to acknowledge exposures at the same time,
especially if Committee Members can agree up front what the major issues are
from an exposure perspective within each specific outcome. Dr. Haskell commented
that a portion of the report could look like tables from systematic scientific
reviews – a concise interpretation of the science.
An additional concern regarding levels of evidence and the unevenness of
evidence in certain population sub-groups was raised by the Committee.
Accordingly, to what extent does the interpretation of the science need to be
slightly unique for a particular sub-group in which very little data exists. Dr.
McTiernan suggested as sub-committees start their work there should be an
agreed-upon list of sub-groups and particular exercise types so that there is
some commonality to everyone's approach. Dr. Nelson commented that the Dietary
Guidelines were really written around exposures and that if the Physical
Activity Guidelines are to complement the Dietary Guidelines the Committee's
work should address exposures or be considered in parallel with work done
revolving around outcomes.
Dr. Yancey asked to what extent will the Committee deal with implementation
methods? In response, Dr. Haskell reiterated that their charge was to document
what the science is relating physical activity to health and not to evaluate the
increasing number of intervention trials that are trying different strategies to
get different populations more physically active. Dr. Haskell also stated while
it was not the job of the Committee to evaluate implementation it might be
helpful to note the type of delivery that was employed (i.e., home-based,
lifestyle, etc.) when reviewing the study.
Further commenting on the issue of levels of evidence, Dr. Rimmer stated that
persons with disabilities is an important group to recognize; however, level A
type evidence may not exist for several disability sub-groups. On the other hand
there is a lot of level B and C type evidence so it may not be appropriate to
base the same model used for other outcome groups when reviewing the evidence in
disability sub-groups. Dr. Haskell responded that Dr. Rimmer's comments speak
directly to a central dilemma of how to apply level-of-evidence concept to a
behavioral intervention since it is difficult to create randomized trials,
similar to pharmaceutical drug trials, and how does the Committee weigh the
different levels of evidence?