Seattle 5 a Day worksite program to increase fruit and vegetable consumption

A site-specific literature review of policy and environmental interventions that promote physical activity and nutrition for cardiovascular health: what works?

OBJECTIVE

To review the literature to determine whether policy and environmental interventions can increase people's physical activity or improve their nutrition.

DATA SOURCES

The following databases were searched for relevant intervention studies: Medline, Chronic Disease Prevention File, PsychInfo, Health Star, Web of Science, ERIC, the U.S. Department of Transportation, and the U.S. Department of Agriculture.

STUDY SELECTION

To be included in the review, studies must have (1) addressed policy or environmental interventions to promote physical activity and/or good nutrition; (2) been published from 1970 to October 2003; (3) provided a description of the intervention; and (4) reported behavioral, physiological, or organizational change outcomes. Studies that had inadequate intervention descriptions or that focused on determinants research, individual-level interventions only, the built environment, or media-only campaigns were excluded.

DATA EXTRACTION

We extracted and summarized studies conducted before 1990 (n = 65) and during 1990-2003 (n = 64).

DATA SYNTHESIS

Data were synthesized by topic (i.e., physical activity or nutrition), by type of intervention (i.e., point-of-purchase), and by setting (i.e., community, health care facility, school, worksite). Current studies published during 1990-2003 are described in more detail, including setting and location, sample size and characteristics, intervention, evaluation period, findings, and research design. Findings are also categorized by type of intervention to show the strength of the study designs and the associations of policy and environmental interventions with physical activity and nutrition.

CONCLUSIONS

The results of our review suggest that policy and environmental strategies may promote physical activity and good nutrition. Based on the experimental and quasi-experimental studies in this review, the following interventions provide the strongest evidence for influencing these behaviors: prompts to increase stair use (N = 5); access to places and opportunities for physical activity (N = 6); school-based physical education (PE) with better-trained PE teachers, and increased length of time students are physically active (N = 7); comprehensive work-site approaches, including education, employee and peer support for physical activity, incentives, and access to exercise facilities (N = 5); the availability of nutritious foods (N = 33), point-of-purchase strategies (N = 29); and systematic officer reminders and training of health care providers to provide nutritional counseling (N = 4). Further research is needed to determine the long-term effectiveness of different policy and environmental interventions with various populations and to identify the steps necessary to successfully implement these types of interventions.

Reliability, effect size, and responsiveness of health status measures in the design of randomized and cluster-randomized trials

BACKGROUND

New health status survey instruments are often described by their psychometric (measurement) properties, such as Validity, Reliability, Effect Size, and Responsiveness. For cluster-randomized trials, another important statistic is the Intraclass Correlation (ICC) for the instrument within clusters. Studies using better instruments can be performed with smaller sample sizes, but better instruments may be more expensive in terms of dollars, opportunity cost, or poorer data quality due to the response burden of longer instruments.

METHODS

We defined the psychometric statistics in terms of a mathematical model, and examined the power of a two-sample test as a function of the test-retest Reliability, Effect Size, Responsiveness, and Intraclass Correlation of the instrument. We examined the "cost-effectiveness" of using a one-item versus a five-item measure of mental health status.

FINDINGS

Under the standard model for measurement error, the psychometric statistics are all functions of the same error term. They are also functions of the setting in which they were estimated. In randomized trials, power is a function of Reliability and sample size, and a less reliable instrument can achieve the desired power if N is increased. In cluster-randomized trials, adequate power may be obtained by increasing the number of clusters per treatment group (and often the number of persons per cluster), as well as by choosing a more reliable instrument. The one-item measure of mental health status may be more cost-effective than the five-item measure in some situations.

CONCLUSION

If the goal is to diagnose or refer individual patients, an instrument with high Validity and Reliability is needed. In settings where the sample sizes are large or can be increased easily, any valid instrument may be cost-effective. It is likely that many published values of psychometric statistics are accurate only in settings similar to that in which they were estimated.

Randomized trial of a low-intensity dietary intervention in rural residents: the Rural Physician Cancer Prevention Project

BACKGROUND

Dietary behavior, specifically a low-fat, high-fiber diet, plays a role in the primary prevention of chronic diseases including cancer.

DESIGN

A community-based randomized trial to assess the impact of a low-intensity, physician-endorsed, self-help dietary intervention that provided tailored dietary feedback, and was designed to promote improved fat and fiber behavior in a rural, low-education/low-literacy, partly minority population. The data were collected from 1999 to 2003.

SETTING/PARTICIPANTS

A total of 754 patients from three physician practices in rural Virginia completed a baseline telephone survey assessing dietary and psychosocial information, and were then randomly assigned to the intervention or control condition. Follow-up telephone evaluation was based on 522 participants at 1 month, 470 at 6 months, and 516 participants at 12 months.

INTERVENTION

A series of tailored feedback, followed by brief telephone counseling and theory-based nutritional education booklets, provided by staggered delivery to the home.

MAIN OUTCOME MEASURES

Dietary fat and fiber behavior, dietary intentions to change, self-efficacy for dietary change, and fat and fiber knowledge.

RESULTS

The intervention group demonstrated significant improvement in dietary fat and fiber behaviors and intentions to change fat and fiber intake (p <0.05) at 1, 6, and 12 months.

CONCLUSIONS

The Rural Physician Cancer Prevention Project provides an effective model for achieving public health-level dietary health behavior changes among a rural, minority, and low-literacy/low-education population.

Multiple tailored messages are effective in increasing fruit and vegetable consumption among callers to the Cancer Information Service

Results are reported from a large (n = 3,402) four-group randomized trial to increase fruit and vegetable consumption among callers to the National Cancer Institute's (NCI's) Cancer Information Service (CIS) using tailored print materials. Following a baseline telephone interview, which included a brief educational message (BEM), participants were assigned randomly within CIS offices to one of four groups: single untailored (SU) group-one untailored set of materials; single tailored (ST) group-one tailored booklet; multiple tailored (MT) group-four tailored materials; and multiple retailored (MRT) group-four tailored materials with retailoring based on new information obtained at 5 months follow-up. Follow-up telephone interviews were conducted at 5 (n = 2,233) and 12 months (n = 1,927) after baseline. The main outcome measure was self-reported fruit and vegetable consumption using a seven-item food frequency questionnaire. At 12 months follow-up, there was a significant linear trend across groups of 0.21 servings (p = 0.0002). Specific nested hypotheses then were tested and revealed significant mean serving differences between SU (5.07) vs. MT (5.64) (p = 0.002) and SU vs. MRT (5.71; p < 0.001). Although the mean for ST (5.40) was greater than that for SU (5.07), the difference was not statistically significant (p = 0.07), and no difference was found between MT vs. MRT (p = 0.69). A higher proportion of recipients of tailored materials reported reading all of the materials and believing that they were written especially for them. No differences by experimental condition were found for the perceived usefulness or motivational impact of the print materials. In this trial, MT print materials were more effective at increasing fruit and vegetable (FV) consumption than were SU materials. The intervention mechanisms responsible for this effect merit further research. Retailoring did not produce a significant difference when compared with longitudinal baseline tailoring.

Evaluation of Community-Intervention Trials via Generalized Linear Mixed Models

In community-intervention trials, communities, rather than individuals, are randomized to experimental arms. Generalized linear mixed models offer a flexible parametric framework for the evaluation of community-intervention trials, incorporating both systematic and random variations at the community and individual levels. We propose here a simple two-stage inference method for generalized linear mixed models, specifically tailored to the analysis of community-intervention trials. In the first stage, community-specific random effects are estimated from individual-level data, adjusting for the effects of individual-level covariates. This reduces the model approximately to a linear mixed model with the unit of analysis being community. Because the number of communities is typically small in community-intervention studies, we apply the small-sample inference method of Kenward and Roger (1997, Biometrics53, 983-997) to the linear mixed model of second stage. We show by simulation that, under typical settings of community-intervention studies, the proposed approach improves the inference on the intervention-effect parameter uniformly over both the linearized mixed-effect approach and the adaptive Gaussian quadrature approach for generalized linear mixed models. This work is motivated by a series of large randomized trials that test community interventions for promoting cancer preventive lifestyles and behaviors.

Diet and cardiovascular disease in the UK: are the messages getting across?

Cardiovascular disease (CVD) is a leading cause of premature death in the UK and a major cause of ill health and disability. Whilst death rates from CVD have been falling since the late 1970s in the UK, levels of morbidity (such as angina) do not seem to be falling and may even be rising in some age-groups, especially as the population ages. There is broad consensus that lifestyle factors, including physical activity and diet, are fundamental determinants of heart disease risk. Current recommendations to reduce cardiovascular risk include maintaining a healthy body weight, eating five or more portions of fruit and vegetables each day, reducing intake of fat (particularly saturated fatty acids), reducing salt intake and eating one portion of oily fish per week. Although some improvements have been made in recent years (e.g. a reduction in total fat intake), national studies suggest that more effective campaigns are required to increase awareness of the benefits of these dietary changes. The present paper will discuss how the dietary messages relating to CVD are best communicated to the general public and will identify some of the main barriers to their implementation.

Design and analysis of group-randomized trials: a review of recent practices

We reviewed group-randomized trials (GRTs) published in the American Journal of Public Health and Preventive Medicine from 1998 through 2002 and estimated the proportion of GRTs that employ appropriate methods for design and analysis. Of 60 articles, 9 (15.0%) reported evidence of using appropriate methods for sample size estimation. Of 59 articles in the analytic review, 27 (45.8%) reported at least 1 inappropriate analysis and 12 (20.3%) reported only inappropriate analyses. Nineteen (32.2%) reported analyses at an individual or subgroup level, ignoring group, or included group as a fixed effect. Hence increased vigilance is needed to ensure that appropriate methods for GRTs are employed and that results based on inappropriate methods are not published.

Leading the Way in Exercise and Diet (Project LEAD): intervening to improve function among older breast and prostate cancer survivors

The U.S. population is aging, bringing with it an increased prevalence of chronic disease and concomitant declines in physical function. The risk of developing cancer increases significantly with age, and functional decline is much more likely once a cancer diagnosis is rendered. Thus, functional status in later life is a key concern, one that is heightened among elders who have been diagnosed with cancer. To date, however, there have been few trials that have exclusively addressed issues related to cancer survivorship among older cancer patients, and to our knowledge, none has focused on preserving or enhancing physical functioning. This paper describes the study design and methodological considerations of a randomized controlled trial to determine if a personally tailored workbook and telephone counseling program can positively affect physical activity and dietary behaviors and ultimately the physical functioning of up to 420 older men and women newly diagnosed with breast or prostate cancer. This trial is unique because the cancer diagnosis is used not only as a marker of risk for functional decline, but also as a "teachable moment" - an opportune time when elders may be more receptive to making beneficial lifestyle changes. Undoubtedly, as cure rates for cancer increase and intersect with ever-growing numbers of elderly, there will be numerous opportunities to provide and test interventions within this vulnerable population and to target functional status as a primary outcome. In reporting our methods, we hope to give others "a leg up," so that they can hurdle with greater ease the barriers we experienced, and thus advance the field more rapidly.

Dietary interventions to prevent disease

Changing dietary behaviors to prevent chronic disease has been an important research focus for the last 25 years. Here we present a review of published articles on the results of research to identify methods to change key dietary habits: fat intake, fiber intake, and consumption of fruits and vegetables. We divided the research reviewed into sections, based on the channel through which the intervention activities were delivered. We conclude that the field is making progress in identifying successful dietary change strategies, but that more can be learned. Particularly, we need to transfer some of the knowledge from the individual-based trials to community-level interventions. Also, more research with rigorous methodology must be done to test current and future intervention options.

Some design issues in a community intervention trial

We present statistical considerations for the design of a 20-community randomized trial. The community intervention aims at multiple cancer prevention health behaviors including reducing dietary fat, increasing fruit and vegetable intake, smoking cessation, and increasing colorectal cancer screening. To better measure the overall impact of the intervention, individual endpoints as well as a global test of multiple endpoints are used. The statistical power analysis takes into account the heterogeneity between communities, the correlation between health behaviors over time, and the correlation between multiple endpoints. The study is being conducted in a relatively confined geographic area. Several measures have been taken to account for potential contamination. These include collecting information in baseline and follow-up surveys on intervention dose and conducting surveys in three similar communities in another part of the state.

Changes in vegetable and fruit consumption and awareness among US adults: results of the 1991 and 1997 5 A Day for Better Health Program surveys

OBJECTIVE

The purpose of this study is to assess population-based changes in vegetable and fruit consumption and psychosocial correlates.

DESIGN

Two nationally representative random digit dial surveys conducted in 1991 and 1997; respondents were queried regarding consumption of and attitudes and knowledge about vegetables and fruit.

SUBJECTS/SETTING

Respondents were 2,755 and 2,544 adults (in 1991 and 1997, respectively) older than 18 years.

STATISTICAL ANALYSIS PERFORMED

Vegetable and fruit consumption and message awareness were measured using weighted-only and regression model-adjusted analyses to assess changes.

RESULTS

Mean vegetable and fruit consumption was significantly (P=.007) higher in 1997 than in 1991 using weighted-only analyses, but remained significant only for Hispanic (P=.03) and nonsmoker (P=.004) subgroups when adjusted for demographic shifts. Significantly higher percentages were found in the model-adjusted analyses for those consuming 5 or more (daily servings (23.4% to 25.8%), message awareness (7.7% to 19.2%), and knowledge of the 5 A Day Program (2.0% to 17.8%).

APPLICATIONS/CONCLUSIONS

A significantly positive change in vegetable and fruit consumption occurred between 1991 and 1997 according to traditional methods of survey data analysis, but null findings resulted when the data were adjusted for demographic shifts. Nutrition professionals should continue targeting specific demographic subgroups with tailored interventions to move all Americans toward achievement of dietary guidelines for vegetable and fruit consumption.