with 4 key questions (Appendix Figure, available at www
.annals.org) that included the effect of dietary or physical
activity counseling on health outcomes (key question 1),
intermediate cardiovascular disease–related outcomes (key
question 2), behavioral outcomes (key question 3), and
harms of the counseling interventions (key question 4).
METHODS
The full report (10) provides a detailed description of
our methods, including search strategies and excluded
studies.
Data Sources and Searches
To identify literature published for each key question
since the previous recommendations, we searched MEDLINE,
PsycINFO, and the Cochrane Central Register of
Controlled Trials from January 2001 to January 2010. We
supplemented our searches with suggestions from experts and
reference lists from other relevant publications, including the
2 previous USPSTF systematic reviews and 9 related existing
reviews (11–21).
Study Selection
Two investigators independently reviewed 13 562 abstracts
and 481 articles against the specified inclusion criteria
(Figure). We included trials with primary care–
relevant counseling on physical activity (for example, aerobic
activities, such as walking, cycling, or swimming, or resistance
training) or healthful diet interventions (for example,
appropriate calorie intake; increased intake of fruits and
vegetables, whole grains, and fiber; balanced intake of fats;
or decreased sodium). We excluded interventions primarily
aimed at weight loss or those that provided controlled diets
or supervised physical activity. Primary care–relevant counseling
included interventions that were conducted in,
judged feasible to be conducted in (such as phone or electronic
interventions), or potentially referable from a primary
care setting. Interventions had to be compared with
usual care, a minimal intervention, or an attention-control
group. We excluded interventions that targeted persons
with known hypertension, hyperlipidemia, diabetes, or cardiovascular
disease and trials in which more than 50% of
the population had known heart disease or any one or a
combination of these risk factors. We required a minimum
follow-up of 6 months after randomization. A priori outcomes
included true health outcomes (morbidity or mortality
related to cardiovascular disease); intermediate outcomes
and physiologic changes associated with health
outcomes (blood pressure, lipid profile, fasting glucose
level and glucose tolerance, and adiposity); and behavioral
outcomes (any self-reported change in physical activity or
dietary intake). We did not include cost-effectiveness or
cost-related outcomes. For harms, we included any observational
studies that reported serious cardiovascular harms,
such as acute cardiac events during or immediately after
physical activity.
Data Extraction and Quality Assessment
Articles that met our inclusion criteria were critically
appraised by 2 reviewers using the USPSTF and National
Institute for Health and Clinical Excellence design-specific
quality criteria (22). The reviewers were each blinded to
the other’s initial ratings, and discrepancies were resolved
by consensus. Articles were rated as good, fair, or poor
quality. Good-quality studies met all of the specified
quality criteria, whereas fair-quality studies did not but
had no fatal flaws in the design, execution, or reporting
of the study. Poor-quality studies were excluded from
this review.
For included studies, 1 investigator extracted data on
study setting, populations, interventions, and prespecified
outcomes into standardized evidence tables and a second
investigator verified all extracted data.
Data Synthesis and Analysis
We conducted random-effects meta-analyses to estimate
the effect size of counseling on all intermediate health
outcomes and behavioral outcomes. We combined all trials
with a given outcome and conducted separate analyses for
each of the 3 intervention targets (physical activity, healthful
diet, and combined) and, if applicable, for the specific
dietary message (sodium reduction, focus on fruits and
vegetables only, or general low-fat or heart-healthy dietary
counseling). Analyses were stratified by estimated intervention
intensity (low [30 minutes], medium [between 31
minutes and 6 hours of contact], or high [6 hours of
contact]). Trials were also categorized by population risk as
being unselected or selected only on the basis of age; selected
for suboptimal behavior (such as sedentary behavior
or poor dietary intake); or selected for individual or population
risk factors for increased incidence of cardiovascular
disease (such as mildly elevated diastolic blood pressure or
fasting glucose or serum lipid levels, obesity, or poverty or
poor access to health care).
We assessed the presence of statistical heterogeneity
among the studies by using standard chi-square tests and
estimated the magnitude of heterogeneity by using the I2
statistic (23). Tests of publication bias to determine
whether the distribution of the effect sizes was symmetric
with respect to the precision measure were performed by
using funnel plots and the Egger linear regression method
(24, 25). Meta-regressions were performed on the basis of
the random-effects models to examine the effect of 4 a
priori variables of heterogeneity (intervention intensity, intervention
target, study population risk, and recruitment
method [volunteer vs. study-identified]) on effect size. To
interpret effect sizes of standardized mean differences, we
used the Cohen d statistic, in which an effect size of 0.2 to
0.3 generally represents a small effect; 0.5, a moderate effect;
and 0.8, a large effect (26).
All analyses were performed by using Stata, version
10.0 (StataCorp, College Station, Texas).
Healthy Lifestyle Counseling to Prevent Cardiovascular Disease Clinical Guideline
www.annals.org 7 December 2010 Annals of Internal Medicine Volume 153 • Number 11 737
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