The Next Step Trial: impact of a worksite colorectal cancer screening promotion program

Intent-to-treat analysis of cluster randomized trials when clusters report unidentifiable outcome proportions

Background

Cluster randomized trials are designed to evaluate interventions at the cluster or group level. When clusters are randomized but some clusters report no or non-analyzable data, intent-to-treat analysis, the gold standard for the analysis of randomized controlled trials, can be compromised. This article presents a very flexible statistical methodology for cluster randomized trials whose outcome is a cluster-level proportion (e.g. proportion from a cluster reporting an event) in the setting where clusters report non-analyzable data (which in general could be due to nonadherence, dropout, missingness, etc.). The approach is motivated by a previously published stratified randomized controlled trial called, “The Randomized Recruitment Intervention Trial (RECRUIT),” designed to examine the effectiveness of a trust-based continuous quality improvement intervention on increasing minority recruitment into clinical trials (ClinicalTrials.gov Identifier: NCT01911208).

Methods

The novel approach exploits the use of generalized estimating equations for cluster-level reports, such that all clusters randomized at baseline are able to be analyzed, and intervention effects are presented as risk ratios. Simulation studies under different outcome missingness scenarios and a variety of intra-cluster correlations are conducted. A comparative analysis of the method with imputation and per protocol approaches for RECRUIT is presented.

Results

Simulation results show the novel approach produces unbiased and efficient estimates of the intervention effect that maintain the nominal type I error rate. Application to RECRUIT shows similar effect sizes when compared to the imputation and per protocol approach.

Conclusion

The article demonstrates that an innovative bivariate generalized estimating equations framework allows one to implement an intent-to-treat analysis to obtain risk ratios or odds ratios, for a variety of cluster randomized designs.

Strategies to improve the implementation of workplace-based policies or practices targeting tobacco, alcohol, diet, physical activity and obesity

BACKGROUND

Given the substantial period of time adults spend in their workplaces each day, these provide an opportune setting for interventions addressing modifiable behavioural risk factors for chronic disease. Previous reviews of trials of workplace-based interventions suggest they can be effective in modifying a range of risk factors including diet, physical activity, obesity, risky alcohol use and tobacco use. However, such interventions are often poorly implemented in workplaces, limiting their impact on employee health. Identifying strategies that are effective in improving the implementation of workplace-based interventions has the potential to improve their effects on health outcomes.

OBJECTIVES

To assess the effects of strategies for improving the implementation of workplace-based policies or practices targeting diet, physical activity, obesity, tobacco use and alcohol use.Secondary objectives were to assess the impact of such strategies on employee health behaviours, including dietary intake, physical activity, weight status, and alcohol and tobacco use; evaluate their cost-effectiveness; and identify any unintended adverse effects of implementation strategies on workplaces or workplace staff.

SEARCH METHODS

We searched the following electronic databases on 31 August 2017: CENTRAL; MEDLINE; MEDLINE In Process; the Campbell Library; PsycINFO; Education Resource Information Center (ERIC); Cumulative Index to Nursing and Allied Health Literature (CINAHL); and Scopus. We also handsearched all publications between August 2012 and September 2017 in two speciality journals: Implementation Science and Journal of Translational Behavioral Medicine. We conducted searches up to September 2017 in Dissertations and Theses, the WHO International Clinical Trials Registry Platform, and the US National Institutes of Health Registry. We screened the reference lists of included trials and contacted authors to identify other potentially relevant trials. We also consulted experts in the field to identify other relevant research.

SELECTION CRITERIA

Implementation strategies were defined as strategies specifically employed to improve the implementation of health interventions into routine practice within specific settings. We included any trial with a parallel control group (randomised or non-randomised) and conducted at any scale that compared strategies to support implementation of workplace policies or practices targeting diet, physical activity, obesity, risky alcohol use or tobacco use versus no intervention (i.e. wait-list, usual practice or minimal support control) or another implementation strategy. Implementation strategies could include those identified by the Effective Practice and Organisation of Care (EPOC) taxonomy such as quality improvement initiatives and education and training, as well as other strategies. Implementation interventions could target policies or practices directly instituted in the workplace environment, as well as workplace-instituted efforts encouraging the use of external health promotion services (e.g. gym membership subsidies).

DATA COLLECTION AND ANALYSIS

Review authors working in pairs independently performed citation screening, data extraction and 'Risk of bias' assessment, resolving disagreements via consensus or a third reviewer. We narratively synthesised findings for all included trials by first describing trial characteristics, participants, interventions and outcomes. We then described the effect size of the outcome measure for policy or practice implementation. We performed meta-analysis of implementation outcomes for trials of comparable design and outcome.

MAIN RESULTS

We included six trials, four of which took place in the USA. Four trials employed randomised controlled trial (RCT) designs. Trials were conducted in workplaces from the manufacturing, industrial and services-based sectors. The sample sizes of workplaces ranged from 12 to 114. Workplace policies and practices targeted included: healthy catering policies; point-of-purchase nutrition labelling; environmental supports for healthy eating and physical activity; tobacco control policies; weight management programmes; and adherence to guidelines for staff health promotion. All implementation interventions utilised multiple implementation strategies, the most common of which were educational meetings, tailored interventions and local consensus processes. Four trials compared an implementation strategy intervention with a no intervention control, one trial compared different implementation interventions, and one three-arm trial compared two implementation strategies with each other and a control. Four trials reported a single implementation outcome, whilst the other two reported multiple outcomes. Investigators assessed outcomes using surveys, audits and environmental observations. We judged most trials to be at high risk of performance and detection bias and at unclear risk of reporting and attrition bias.Of the five trials comparing implementation strategies with a no intervention control, pooled analysis was possible for three RCTs reporting continuous score-based measures of implementation outcomes. The meta-analysis found no difference in standardised effects (standardised mean difference (SMD) -0.01, 95% CI -0.32 to 0.30; 164 participants; 3 studies; low certainty evidence), suggesting no benefit of implementation support in improving policy or practice implementation, relative to control. Findings for other continuous or dichotomous implementation outcomes reported across these five trials were mixed. For the two non-randomised trials examining comparative effectiveness, both reported improvements in implementation, favouring the more intensive implementation group (very low certainty evidence). Three trials examined the impact of implementation strategies on employee health behaviours, reporting mixed effects for diet and weight status (very low certainty evidence) and no effect for physical activity (very low certainty evidence) or tobacco use (low certainty evidence). One trial reported an increase in absolute workplace costs for health promotion in the implementation group (low certainty evidence). None of the included trials assessed adverse consequences. Limitations of the review included the small number of trials identified and the lack of consistent terminology applied in the implementation science field, which may have resulted in us overlooking potentially relevant trials in the search.

AUTHORS' CONCLUSIONS

Available evidence regarding the effectiveness of implementation strategies for improving implementation of health-promoting policies and practices in the workplace setting is sparse and inconsistent. Low certainty evidence suggests that such strategies may make little or no difference on measures of implementation fidelity or different employee health behaviour outcomes. It is also unclear if such strategies are cost-effective or have potential unintended adverse consequences. The limited number of trials identified suggests implementation research in the workplace setting is in its infancy, warranting further research to guide evidence translation in this setting.

Processes of Change for Colonoscopy: Limited Support for Use Among Navigated Latinos

This study assessed the role of the processes of change (POC), a construct of the transtheoretical model, in colorectal cancer (CRC) screening among Latinos. Latinos participate in CRC screening less often and are diagnosed with CRC at a later stage than whites. POC items were administered to 344 English- and Spanish-speaking Latinos at average risk for CRC who had not had a colonoscopy in the past 5 years and received a colonoscopy referral. POC were measured at three timepoints: following informed consent (T1) at time of referral, 2 weeks prior to scheduled colonoscopy (T2), and 1 month after scheduled colonoscopy (T3). Participants received patient navigation as part of a randomized controlled trial to promote screening colonoscopy. POC scores were examined for changes during the course of the intervention, and logistic regression models assessed the relationship between POC scores and CRC screening adherence. Total POC scores decreased between T1 and T2 (p = 0.03) but were unchanged between T1 and T3. CRC screening adherence was not significantly associated with POC scores or change in POC scores over time. The POC instrument was not found useful for predicting colonoscopy adherence among Latinos in conjunction with patient navigation. Total POC scores did not increase during a patient navigation intervention despite high colonoscopy completion rates.

Continuous time Markov chain approaches for analyzing transtheoretical models of health behavioral change: A case study and comparison of model estimations

Continuous time Markov chain models are frequently employed in medical research to study the disease progression but are rarely applied to the transtheoretical model, a psychosocial model widely used in the studies of health-related outcomes. The transtheoretical model often includes more than three states and conceptually allows for all possible instantaneous transitions (referred to as general continuous time Markov chain). This complicates the likelihood function because it involves calculating a matrix exponential that may not be simplified for general continuous time Markov chain models. We undertook a Bayesian approach wherein we numerically evaluated the likelihood using ordinary differential equation solvers available from the gnu scientific library. We compared our Bayesian approach with the maximum likelihood method implemented with the R package MSM. Our simulation study showed that the Bayesian approach provided more accurate point and interval estimates than the maximum likelihood method, especially in complex continuous time Markov chain models with five states. When applied to data from a four-state transtheoretical model collected from a nutrition intervention study in the next step trial, we observed results consistent with the results of the simulation study. Specifically, the two approaches provided comparable point estimates and standard errors for most parameters, but the maximum likelihood offered substantially smaller standard errors for some parameters. Comparable estimates of the standard errors are obtainable from package MSM, which works only when the model estimation algorithm converges.

Colorectal cancer screening in Korean workers: using a stage model approach to examine the ecological predictors of behavior

BACKGROUND

Early detection is important for reducing mortality by colorectal cancer. Workplaces have access to a large number of people, approximately half of the Korean population. For cancer prevention, it is necessary to approach cancer screening through the workplace.

OBJECTIVE

In this cross-sectional study, we aimed to identify colorectal cancer screening (CRCS) stages and to predict factors that affect the respective stages.

METHODS

Data were collected from 314 manual workers at 32 medium-sized and small workplaces located in Korea. The dependent variable was the stage of CRCS, and independent variables were intrapersonal, interpersonal, and organizational levels.

RESULTS

At the intrapersonal level, workers who increased work hours per week or who felt stress were less likely to be in the acting/maintenance stage than in the decided to act stage of CRCS. At the organizational level, workers in medium-sized workplaces, those whose administrators secured health checkup and cancer screening budget for their workplace, and those considering health checkup and cancer screening were more likely to be in the acting/maintenance stage, compared with the decided to act stage.

CONCLUSIONS

Our findings suggest that the respective stages are affected by different intrapersonal, interpersonal, and organizational factors.

IMPLICATION FOR PRACTICE

The workplace environment and organizational predictors before the implementation of CRCS promotion programs may produce better results.

Analysis of transtheoretical model of health behavioral changes in a nutrition intervention study--a continuous time Markov chain model with Bayesian approach

Continuous time Markov chain (CTMC) models are often used to study the progression of chronic diseases in medical research but rarely applied to studies of the process of behavioral change. In studies of interventions to modify behaviors, a widely used psychosocial model is based on the transtheoretical model that often has more than three states (representing stages of change) and conceptually permits all possible instantaneous transitions. Very little attention is given to the study of the relationships between a CTMC model and associated covariates under the framework of transtheoretical model. We developed a Bayesian approach to evaluate the covariate effects on a CTMC model through a log-linear regression link. A simulation study of this approach showed that model parameters were accurately and precisely estimated. We analyzed an existing data set on stages of change in dietary intake from the Next Step Trial using the proposed method and the generalized multinomial logit model. We found that the generalized multinomial logit model was not suitable for these data because it ignores the unbalanced data structure and temporal correlation between successive measurements. Our analysis not only confirms that the nutrition intervention was effective but also provides information on how the intervention affected the transitions among the stages of change. We found that, compared with the control group, subjects in the intervention group, on average, spent substantively less time in the precontemplation stage and were more/less likely to move from an unhealthy/healthy state to a healthy/unhealthy state.

Underuse of surveillance colonoscopy in patients at increased risk of colorectal cancer

OBJECTIVES

Colorectal cancer incidence and mortality have declined over the past two decades, and much of this improvement is attributed to increased use of screening. Approximately 25% of patients who undergo screening colonoscopy have premalignant adenomas that require removal and follow-up colonoscopy. However, there are few studies of the use of surveillance colonoscopy in increased risk patients with previous adenomas.

METHODS

We conducted a cross-sectional study to examine factors associated with underuse of surveillance colonoscopy among patients who are at increased risk for colorectal cancer. The study population consisted of patients with previously identified adenomatous polyps and who were due for follow-up colonoscopy. Patients were categorized as attenders (n=100) or non-attenders (n=104) on the basis of completion of follow-up colonoscopy. Telephone surveys assessed the use of surveillance colonoscopy across domains of predisposing patient characteristics, enabling factors, and patient need. Mutlivariable logistic regression was used to identify factors associated with screening completion.

RESULTS

Perceived barriers, perceived benefits, social deprivation, and cancer worry were associated with attendance at colonoscopy. Higher benefits (odds ratio (OR) 2.37, 95% confidence interval (CI) 1.04-5.41) and cancer worry (OR 1.73, 95% CI 1.07-2.79) increased the odds of attendance at follow-up colonoscopy, whereas greater barriers (OR 0.49, 95% CI 0.28-0.88) and high social deprivation (≥2; OR 0.09, 95% CI 0.01-0.76) were associated with lower odds.

CONCLUSIONS

Our results suggest that multilevel factors contribute to the use of surveillance colonoscopy in higher risk populations, many of which are amenable to intervention. Interventions, such as patient navigation, may help facilitate appropriate use of surveillance colonoscopy.

Longitudinal predictors of colorectal cancer screening among participants in a randomized controlled trial

OBJECTIVE

Few studies use longitudinal data to identify predictors of colorectal cancer screening (CRCS). We examined predictors of (1) initial CRCS during the first year of a randomized trial, and (2) repeat CRCS during the second year of the trial among those that completed FOBT in Year 1.

METHODS

The sample comprised 1247 participants of the Systems of Support to Increase Colorectal Cancer Screening (SOS) Trial (Group Health Cooperative, August 2008 to November 2011). Potential predictors of CRCS were identified with logistic regression and included sociodemographics, health history, and validated scales of psychosocial constructs.

RESULTS

Prior CRCS (OR 2.64, 95% CI 1.99-3.52) and intervention group (Automated: OR 2.06 95% CI 1.43-2.95; Assisted: OR 4.03, 95% CI 2.69-6.03; Navigated: OR 5.64, 95% CI 3.74-8.49) were predictors of CRCS completion at Year 1. For repeat CRCS at Year 2, prior CRCS at baseline (OR 1.97, 95% CI 1.25-3.11), intervention group (Automated: OR 9.27, 95% CI 4.56-18.82; Assisted: OR 11.17, 95% CI 5.44-22.94; Navigated: OR 13.10, 95% CI 6.33-27.08), and self-efficacy (OR 1.32, 95% CI 1.00-1.73) were significant predictors.

CONCLUSION

Self-efficacy and prior CRCS are important predictors of future screening behavior. CRCS completion increased when access barriers were removed through interventions.

A comparison of different strategies used to invite subjects with a positive faecal occult blood test to a colonoscopy assessment. A randomised controlled trial in population-based screening programmes

OBJECTIVE

The purpose of this parallel randomised controlled trial was to compare compliance with different modalities used to invite patients with a positive immunochemical faecal occult blood test (FIT+) for a total colonoscopy (TC).

METHOD

FIT+ patients from nine Italian colorectal cancer screening programmes were randomised to be invited for a TC initially by mail or by phone and, for non-compliers, to be recalled by mail, for counselling with a general practitioner, or to meet with a specialist screening practitioner (nurse or healthcare assistant).

RESULTS

In all, 3777 patients were randomised to different invitation strategies. Compliance with an initial invitation by mail and by phone was similar (86.0% vs. 84.0%, relative risk - RR: 1.02; 95%CI 0.97-1.08). Among non-responders to the initial invitation, compliance with a recall by appointment with a specialist practitioner was 50.4%, significantly higher than with a mail recall (38.1%; RR:1.33; 95%CI 1.01-1.76) or with a face-to-face counselling with the GP (30.8%; RR:1.45;95%CI 1.14-1.87).

CONCLUSION

Compliance with an initial invitation for a TC by mail and by phone was similar. A personal meeting with a specialist screening practitioner was associated with the highest compliance among non-compliers with initial invitations, while the involvement of GPs in this particular activity seemed less effective.

Telephone-delivered behavioral intervention among blacks with sleep apnea and metabolic syndrome: study protocol for a randomized controlled trial

Background

Lack of adherence to recommended treatment for obstructive sleep apnea remains an ongoing public health challenge. Despite evidence that continuous positive airway pressure (CPAP) is effective and improves overall quality of life, adherence with the use of CPAP in certain racial/ethnic groups, especially blacks, is suboptimal. Evidence indicates that the incidence and prevalence of obstructive sleep apnea are higher among blacks, relative to whites, and blacks are less likely to adhere to recommended treatment compared with other racial/ethnic groups.

Methods

Using a two-arm randomized controlled design, this study will evaluate the effectiveness of a culturally and linguistically tailored telephone-delivered intervention to promote adherence to physician-recommended sleep apnea assessment and treatment among blacks with metabolic syndrome, versus an attention-control arm. The intervention is designed to foster adherence to recommended sleep apnea care using the stages-of-change model. The intervention will be delivered entirely over the telephone. Participants in the intervention arm will receive 10 phone calls to address challenges and barriers to recommended care. Outcomes will be assessed at baseline, and at 6- and 12-months post-randomization.

Discussion

This tailored behavioral intervention will improve adherence to sleep apnea assessment and treatment among blacks with metabolic syndrome. We expect to demonstrate that this intervention modality is feasible in terms of time and cost and can be replicated in populations with similar racial/ethnic backgrounds.

Trial registration

The study is registered at clinicaltrials.gov NCT01946659 (February 2013)

Clinical and psychosocial variables associated with behavioral intentions to undergo surveillance endoscopy

Background

Many patients with Barrett’s esophagus do not adhere to guideline-recommended endoscopic surveillance. Among patient factors related to cancer prevention behaviors, patients’ stated behavioral intention is a strong predictor of behavior performance. Little is known about the patient factors associated with having a strong behavioral intention to pursue surveillance endoscopy. This study explores the association of clinical and psychosocial variables and behavioral intention to pursue surveillance endoscopy among patients with Barrett’s Esophagus and no or low-grade dysplasia.

Methods

Potential subjects were screened using electronic medical records of a regional Veterans Affairs Medical Center and a pathologically confirmed Barrett’s esophagus registry. Eligible participants were recruited by a mailer or phone call and completed a questionnaire to measure six distinct psychosocial factors, their behavioral intention to undergo surveillance endoscopy, and various demographic and clinical variables. Univariate and multivariate linear regression identified the relation of behavioral intention with each of six psychosocial variables.

Results

One-hundred and one subjects consented and returned surveys. The analytical sample for this study consists of the 94% of surveys with complete responses to the behavior intention items. Three of the six psychosocial domains were statistically significant predictors of intention in both univariate and adjusted univariate analysis (salience/coherence β = 0.59, 95% CI = 0.45-0.76, P <0.01; self-efficacy β = 0.30, 95% CI = 0.10-0.51, P <0.01; and social influence β = 0.20, 95% CI = 0.08-0.33, P <0.01). In a multivariate analysis only salience/coherence (β = 0.65, 95% CI = 0.42-0.88, P <0.01) remained statistically significant predictor of intention.

Conclusion

This study established the validity of a scale to measure psychosocial variables associated with behavioral intentions to undergo surveillance endoscopy. Results demonstrate the importance of assessing self-efficacy, social influences, and bottom-line belief in the value of surveillance endoscopy when evaluating a patient’s likelihood of completing surveillance endoscopy.

Comparing tailored and narrative worksite interventions at increasing colonoscopy adherence in adults 50-75: a randomized controlled trial

Research has identified several communication strategies that could increase adherence to colorectal cancer screening recommendations. Two promising strategies are tailoring and narrative-based approaches. Tailoring is the personalization of information based on individual characteristics. Narrative-based approaches use stories about similar others to counter perceived barriers and cultivate self-efficacy. To compare these two approaches, a randomized controlled trial was carried out at 8 worksites in Indiana. Adults 50-75 (N = 209) received one of four messages about colorectal cancer screening: stock, narrative, tailored, tailored narrative. The primary outcome was whether participants filed a colonoscopy claim in the 18 months following the intervention. Individuals receiving narrative messages were 4 times more likely to screen than those not receiving narrative messages. Tailoring did not increase screening behavior overall. However, individuals with higher cancer information overload were 8 times more likely to screen if they received tailored messages. The results suggest that narrative-based approaches are more effective than tailoring at increasing colorectal cancer screening in worksite interventions. Tailoring may be valuable as a strategy for reaching individuals with high overload, perhaps as a follow-up effort to a larger communication campaign.

Understanding the durability of a fire department wellness program

OBJECTIVES

To understand the influences associated with durability and diffusion of benefits of a fire service wellness program.

METHODS

Qualitative assessment of group interviews.

RESULTS

Five years following a controlled worksite wellness trial, behavioral improvements were durable and had diffused to control participants. These findings were associated with firefighters' team orientation, enacted healthy norms and competitiveness regarding the results of annual health assessments. The original intervention trial appeared to initiate individual change that coalesced into group effects. Secondary influences included increasing public awareness about health, newly hired younger firefighters, and a modicum of administrative support. Culture shift was achieved at the workplace.

CONCLUSIONS

Although the fire service is a unique occupation, these findings suggest general strategies to achieve durable positive health change in other occupational settings.

Strategies and resources to address colorectal cancer screening rates and disparities in the United States and globally

Colorectal cancer is a significant cause of mortality in the United States and globally. In the United States, increased access to screening and effective treatment has contributed to a reduction in colorectal cancer incidence and mortality for the general population, though significant disparities persist. Worldwide, the disparities are even more pronounced, with vastly different colorectal cancer mortality rates and trends among nations. Newly organized colorectal cancer screening programs in economically developed countries with a high burden of colorectal cancer may provide pathways to reduce these disparities over time. This article provides an overview of colorectal cancer incidence, mortality, screening, and disparities in the United States and other world populations. Promising strategies and resources are identified to address colorectal cancer screening rates and disparities in the United States and worldwide.

Implementation and process evaluation of a workplace colorectal cancer screening program in eastern Washington

Colorectal cancer screening is a life-saving intervention, but screening rates are low. The authors implemented and evaluated the Spokane Colorectal Cancer Screening Program-a novel worksite intervention to promote colorectal cancer screening that used a combination of evidence-based strategies recommended by the Guide to Community Preventive Services, as well as additional strategies. Over a period of approximately 3 months, participating worksites held one or more physician-led seminars about colorectal cancer screening for employees. They also distributed free fecal immunochemical tests at the worksite to employees 50 years and older, and they provided test results to employees and their primary care physician. The authors measured attendance at seminars, test kits taken and returned, employee awareness of the program, and colorectal cancer screening rates in participating and comparison worksites. It is estimated that 9% of eligible employees received kits at the worksite, and 4% were screened with these kits. The Spokane Colorectal Cancer Screening Program was a promising pilot test of an innovative worksite screening program that successfully translated evidence-based strategies into practical use in a brief period of time, and it merits a larger study to be able to test its effects more rigorously.

Interventions to promote colorectal cancer screening: an integrative review

Behavior change interventions to promote colorectal cancer (CRC) screening have targeted people in community and primary care settings, health care providers, and health systems. Randomized controlled trials provide the strongest evidence of intervention efficacy. The purpose of this integrative review was to evaluate trials of CRC screening interventions published between 1997 and 2007 and to identify knowledge gaps and future directions for research. Thirty-three randomized trials that met inclusion criteria were evaluated using a modified version of the TREND criteria. Significant intervention effects were reported in 6 of 10 trials focused on increasing fecal occult blood testing, 4 of 7 trials focused on sigmoidoscopy or colonoscopy completion, and 9 of 16 trials focused on completion of any screening test. Several effective interventions to promote CRC screening were identified. Future trials need to use theory to guide interventions, examine moderators and mediators, consistently report results, and use comparable outcome measures.

Distinguishing factors for asymptomatic colonoscopy screening

Demographic, medical history, physician factors, knowledge, beliefs and perceived barriers related to colorectal cancer (CRC) and CRC screening were compared for age-eligible individuals who received asymptomatic colonoscopy screening (n=100) versus those who did not receive any kind of CRC screening (n=142). All participants had health insurance that covered the full cost of colonoscopy screening. Screeners were more likely to have lower levels of income and education, to know the purpose of a colonoscopy, believe it was more normative, and report fewer barriers. Addressing these and other factors associated with CRC screening warrant testing as empirically based interventions.

A randomized trial comparing the effect of two phone-based interventions on colorectal cancer screening adherence

BACKGROUND

Early-stage diagnosis of colorectal cancer is associated with high survival rates; screening prevalence, however, remains suboptimal.

PURPOSE

This study seeks to test the hypothesis that participants receiving telephone-based tailored education or motivational interviewing had higher colorectal cancer screening completion rates compared to usual care.

METHODS

Primary care patients not adherent with colorectal cancer screening and with no personal or family history of cancer (n = 515) were assigned by block randomization to control (n = 169), tailored education (n = 168), or motivational interview (n = 178). The response rate was 70%; attrition was 24%.

RESULTS

Highest screening occurred in the tailored education group (23.8%, p < .02); participants had 2.2 times the odds of completing a post-intervention colorectal cancer screening than did the control group (AOR = 2.2, CI = 1.2-4.0). Motivational interviewing was not associated with significant increase in post-intervention screening.

CONCLUSIONS

Tailored education showed promise as a feasible strategy to increase colorectal cancer screening.

Cluster randomized trials of cancer screening interventions: are appropriate statistical methods being used?

The design and analysis of cluster randomized trials can require more sophistication than individually randomized trials. However, the need for statistical methods that account for the clustered design has not always been appreciated, and past reviews have found widespread deficiencies in methodology and reporting. We reviewed cluster randomized trials of cancer screening interventions published in 1995-2010 to determine whether the use of appropriate statistical methods had increased over time. Literature searches yielded 50 articles reporting outcome analyses of cluster randomized trials of breast, cervix and colorectal cancer screening interventions. Of studies published in 1995-1999, 2000-2002, 2003-2006 and 2007-2010, 55% (6/11), 82% (9/11), 92% (12/13) and 60% (9/15) used appropriate analytic methods, respectively. Results were suggestive of a peak in 2003-2006 (p =.06) followed by a decline in 2007-2010 (p =.08). While the sample of studies was small, these results indicate that many cluster randomized trials of cancer screening interventions have had deficiencies in the application of correct statistical procedures for the outcome analysis, and that increased adoption of appropriate methods in the early and mid-2000's may not have been sustained.

Examining the role of perceived susceptibility on colorectal cancer screening intention and behavior

Although support exists for multiple psychosocial predictors of colorectal cancer (CRC) screening, little is known about the relationships among these variables. Understanding the associations between such predictors could refine health behavior theories and inform the design of interventions. In addition to direct effects, we examined whether baseline perceived susceptibility was a moderator of, or was mediated by, changes in other psychosocial determinants of CRC screening intention and behavior. Longitudinal path models were tested using data from 1,001 white male automotive workers who participated in The Next Step Trial. Our sample included workers with no history of CRC who were due for CRC screening but did not complete CRC screening prior to the assessment of hypothesized mediators at year 1 follow-up. Perceived susceptibility interacted differently with four psychosocial constructs in models predicting CRC screening intention or behavior. Perceived susceptibility was independent of perceived benefits, moderated the change in perceived barriers and self-efficacy, and was mediated by the change in family influence. The role of perceived susceptibility was not limited to direct effects but involved mediating and moderating pathways of influence.

A systematic review of selected interventions for worksite health promotion. The assessment of health risks with feedback

BACKGROUND

Many health behaviors and physiologic indicators can be used to estimate one's likelihood of illness or premature death. Methods have been developed to assess this risk, most notably the use of a health-risk assessment or biometric screening tool. This report provides recommendations on the effectiveness of interventions that use an Assessment of Health Risks with Feedback (AHRF) when used alone or as part of a broader worksite health promotion program to improve the health of employees.

EVIDENCE ACQUISITION

The Guide to Community Preventive Services' methods for systematic reviews were used to evaluate the effectiveness of AHRF when used alone and when used in combination with other intervention components. Effectiveness was assessed on the basis of changes in health behaviors and physiologic estimates, but was also informed by changes in risk estimates, healthcare service use, and worker productivity.

EVIDENCE SYNTHESIS

The review team identified strong evidence of effectiveness of AHRF when used with health education with or without other intervention components for five outcomes. There is sufficient evidence of effectiveness for four additional outcomes assessed. There is insufficient evidence to determine effectiveness for others such as changes in body composition and fruit and vegetable intake. The team also found insufficient evidence to determine the effectiveness of AHRF when implemented alone.

CONCLUSIONS

The results of these reviews indicate that AHRF is useful as a gateway intervention to a broader worksite health promotion program that includes health education lasting > or =1 hour or repeating multiple times during 1 year, and that may include an array of health promotion activities. These reviews form the basis of the recommendations by the Task Force on Community Preventive Services presented elsewhere in this supplement.

Nutritious food intake: a new competitive advantage for organizations?

Purpose

The purpose of this paper is to suggest that nutritious food intake is a somewhat overlooked yet essential aspect of corporate wellness that has the potential to help provide organizations with a sustainable competitive advantage.

Design/methodology/approach

The paper first discusses the resource‐based view, identifying ways in which nutritious food intake across an organization may serve to create rare and inimitable organizational resources leading to a competitive advantage. It then presents a basic overview of the fundamentals of nutritious food intake. It proceeds to review the transtheoretical stages of change model in the context of tailored nutrition interventions in organizations, providing a detailed overview of key individual behavior focused and environmental focused change strategies along with a discussion of types of technical delivery systems.

Findings

The paper suggests that an organization may be able to use a tailored stage‐based nutrition intervention as part of a comprehensive wellness program in order to help create a sustainable competitive advantage based on the nutritious food intake of its members.

Research limitations/implications

Future researchers should continue to examine the effectiveness of stage‐based computer tailored nutrition interventions and their delivery systems, particularly in the context of comprehensive corporate wellness plans and the extent to which this serves to create a competitive advantage through lower direct healthcare costs and higher worker productivity.

Practical implications

Organizational leaders should carefully consider the strategies and methodologies presented in this paper when designing and implementing nutrition interventions as part of a broad corporate wellness program.

Originality/value

This paper makes a valuable contribution to the organizational literature by recognizing the potential for the application of the transtheoretical stages of change model from the field of nutrition education within the context of the resource‐based view of organizations.

Design and analysis of group-randomized trials in cancer: a review of current practices

BACKGROUND

Previous reviews have identified problems in the design and analysis of group-randomized trials in a number of areas. Similar problems may exist in cancer research, but there have been no comprehensive reviews.

METHODS

We searched Medline and PubMed for group-randomized trials focused on cancer prevention and control that were published between 2002 and 2006. We located and reviewed 75 articles to determine whether articles included evidence of taking group randomization into account in establishing the size of the trial, such as reporting the expected intraclass correlation, the group component of variance, or the variance inflation factor. We also examined the analytical approaches to determine their appropriateness.

RESULTS

Only 18 (24%) of the 75 articles documented appropriate methods for sample size calculations. Only 34 (45%) limited their reports to analyses judged to be appropriate. Fully 26 (34%) failed to report any analyses that were judged to be appropriate. The most commonly used inappropriate analysis was an analysis at the individual level that ignored the groups altogether. Nine articles (12%) did not provide sufficient information.

CONCLUSIONS

Many investigators who use group-randomized trials in cancer research do not adequately attend to the special design and analytic challenges associated with these trials. Failure to do so can lead to reporting type I errors as real effects, mislead investigators and policy-makers, and slow progress toward control and prevention of cancer. A collaborative effort by investigators, statisticians, and others will be required to ensure that group-randomized trials are planned and analyzed using appropriate methods so that the scientific community can have confidence in the published results.

Workplace colorectal cancer-screening awareness programs: an adjunct to primary care practice?

Although regular screening can decrease morbidity and mortality from colorectal cancer, screening rates nationwide are suboptimal due to a lack of organized screening programs. Since workplace colorectal cancer-awareness programs can potentially mitigate both patient and physician barriers to screening, we assessed the workplace as a venue for implementing a colorectal cancer screening-awareness program. In this cross-sectional study, 3756 members of the Toronto Police Service attended an education session about colorectal cancer; 965 of these members gave their informed consent and completed a 5-item colorectal cancer risk-assessment questionnaire. Nearly one-third (30.9%, or 298/965) of this relatively young population (83.1%, or 802/965, < 50 years of age) were at average or above-average risk for colorectal cancer. In the Toronto Police Service population, the workplace was a useful adjunct to reliance on primary care physicians to raise awareness about this important public health issue. These findings should encourage the development of further Canadian workplace colorectal cancer-screening awareness programs.

Using tailored telephone counseling to accelerate the adoption of colorectal cancer screening

BACKGROUND

Few interventions to increase colorectal cancer screening have used a stage of change model to promote screening adoption. None have used computer-assisted tailored telephone counseling calls. This study's purpose was to implement and evaluate stage-based computer-assisted tailored telephone counseling to promote colorectal cancer screening in a primary care population.

METHODS

This randomized controlled trial used a two-stepped intervention that included a mailed booklet on colorectal cancer screening followed by computer-assisted telephone counseling that was based on the Precaution Adoption Process Model. Chart audit was used to document completion of colonoscopy, sigmoidoscopy or fecal occult blood testing.

RESULTS

Record audits were completed on 2,474 (88%) of the 2,817 eligible participants. There was no significant difference in the frequency and nature of the screening tests completed in the study arms. In a sub-analysis, stages of adoption were evaluated pre- and post-telephone counseling. Over half those receiving counseling reported a change in stage towards screening adoption.

CONCLUSION

Overall, the intervention did not increase colorectal screening compared to control. Two possible reasons for the absence of a screening effect include: (a) the focus of the protocol on education for most patients rather than motivation, and (b) the requirement that patients interested in screening seek further information and a referral on their own from their providers. While those receiving telephone counseling improved their stage of adoption, we cannot rule out selection bias. Stronger physician recommendation to speak with the counselors could improve call acceptance. Future colorectal screening should address these weaknesses.

Correlates and predictors of colorectal cancer screening among male automotive workers

BACKGROUND

Most studies examining factors associated with colorectal cancer (CRC) screening (CRCS) are cross-sectional and thus temporal relationships cannot be determined. Furthermore, less attention has been paid to psychosocial predictors of CRCS. We examined both cross-sectional correlates of prior CRCS and predictors of prospective CRCS initiation and maintenance during The Next Step Trial, a 2-year worksite behavioral intervention to promote regular CRCS and dietary change.

METHOD

The sample included 2,693 White male automotive workers at increased occupational risk for, but no history of, CRC who completed a baseline survey. Stratified analyses were conducted for three dependent variables (prior CRCS, CRCS initiation, and CRCS maintenance). We also assessed prior CRCS as a moderator in prospective analyses. Multivariable logistic regression analyses with generalized linear mixed models were used to adjust for cluster sampling.

RESULTS

Except for education, cross-sectional correlates of prior CRCS including older age, family history of CRC or polyps, personal history of polyps, self-efficacy, family support, and intention were also significant prospective predictors of increased CRCS during the trial. Despite differences in the patterns of association for CRCS initiation and maintenance in stratified analyses, the only associations with prospective CRCS that were significantly moderated by prior CRCS were family history and CRCS availability.

CONCLUSIONS

Correlates of prior CRCS that also were prospective predictors of CRCS may be suitable targets for intervention. Additionally, intervention messages addressing psychosocial constructs may be relevant for both CRCS initiation and maintenance. However, studies with more diverse samples are needed to replicate the results reported here.

Telephone outreach to increase colorectal cancer screening in an urban minority population

OBJECTIVES

We compared the effectiveness of a telephone outreach approach versus a direct mail approach in improving rates of colorectal cancer (CRC) screening in a predominantly Black population.

METHODS

A randomized trial was conducted between 2000 and 2003 that followed 456 participants in the New York metropolitan area who had not had recent CRC screening. The intervention group received tailored telephone outreach, and the control group received mailed printed materials. The primary outcome was medically documented CRC screening 6 months or less after randomization.

RESULTS

CRC screening was documented in 61 of 226 (27.0%) intervention participants and in 14 of 230 (6.1%) controls (prevalence rate difference=20.9%; 95% CI = 14.34, 27.46). Compared with the control group, the intervention group was 4.4 times more likely to receive CRC screening within 6 months of randomization.

CONCLUSIONS

Tailored telephone outreach can increase CRC screening in an urban minority population.

Estimating development cost for a tailored interactive computer program to enhance colorectal cancer screening compliance

The authors used an actual-work estimate method to estimate the cost of developing a tailored interactive computer education program to improve compliance with colorectal cancer screening guidelines in a large multi-specialty group medical practice. Resource use was prospectively collected from time logs, administrative records, and a design and computing subcontract. Sensitivity analysis was performed to examine the uncertainty of the overhead cost rate and other parameters. The cost of developing the system was Dollars 328,866. The development cost was Dollars 52.79 per patient when amortized over a 7-year period with a cohort of 1,000 persons. About 20% of the cost was incurred in defining the theoretic framework and supporting literature, constructing the variables and survey, and conducting focus groups. About 41% of the cost was for developing the messages, algorithms, and constructing program elements, and the remaining cost was to create and test the computer education program. About 69% of the cost was attributable to personnel expenses. Development cost is rarely estimated but is important for feasibility studies and ex-ante economic evaluations of alternative interventions. The findings from this study may aid decision makers in planning, assessing, budgeting, and pricing development of tailored interactive computer-based interventions.

Promoting use of colorectal cancer screening tests. Can we change physician behavior?

BACKGROUND

Colorectal cancer (CRC) screening is underutilized despite evidence that screening reduces mortality.

OBJECTIVE

To assess the effect of an intervention targeting physicians and their patients on rates of CRC screening.

DESIGN

A randomized clinical trial of community physicians and their patients.

PARTICIPANTS

Ninety-four community primary care physicians randomly assigned to an intervention consisting of academic detailing and direct mailings to patients or a control group. Patients aged 50 to 79 years in the intervention group physicians received a letter from their physician, a brochure on CRC screening, and a packet of fecal occult blood test (FOBT) cards.

MEASUREMENTS

After 1 year we measured receipt of the following: (1) FOBT in the past 2 years, (2) flexible sigmoidoscopy (SIG) or colonoscopy (COL) in the previous 5 years, and (3) any CRC screening. We report the percent change from baseline in both groups.

RESULTS

9,652 patients were enrolled for 2 years, and 3,732 patients were enrolled for 5 years. There was no increase in any CRC screening that occurred in the intervention group for patients enrolled for 2 years (12.7 increase vs 12.5%, P=.51). Similar results were seen for any CRC screening among patients enrolled for 5 years (9.7% increase vs 8.6%, P=.45). The only outcome on which the intervention had an effect was on patient rates of screening SIG (7.4% increase vs 4.4%, P<.01).

CONCLUSION

With the exception of an increase in rates of SIG in the intervention group, the intervention had no effect on rates of CRC screening. Future interventions should assess innovative approaches to increase rates of CRC screening.

Increasing colorectal cancer screening among individuals in the carpentry trade: test of risk communication interventions

BACKGROUND

Individuals in the carpentry trade, due to lifestyle habits and occupational exposures, may be at above-average risk for colorectal cancer (CRC). Based on the literature which suggests that increasing perceived risk motivates behavior change, we report on the effectiveness of four risk-communication interventions targeted to increase initial, yearly and repeat fecal occult screening (FOBT) among carpenters (N = 860) over a 3-year period.

METHODS

Our 2 x 2 factorial design intervention study varied two dimensions of providing CRC risk factor information: (1) type of risk factor-one set of interventions emphasized three basic risk factors (age, family history and polyps); the other set emphasized a comprehensive set of risk factors including basic, lifestyle, and occupational factors, and (2) tailoring/not tailoring risk factor information. Participants were provided FOBTs. Outcomes were the proportion of returned FOBTs.

RESULTS

Varying the amount and intensity of delivering CRC risk factors information affected neither risk perceptions nor initial, yearly, or repeat screening. However, yearly and repeat screening rates were greater among participants who received interventions addressing comprehensive set of risk factors, especially with increasing age.

CONCLUSIONS

Tailoring on several CRC risk factors appears insufficient to increase and sustain elevated perceptions of CRC risks to promote screening.

The efficacy of tailored print materials in promoting colorectal cancer screening: results from a randomized trial involving callers to the National Cancer Institute's Cancer Information Service

In this large randomized trial among callers to the Cancer Information Service (CIS), tailored print materials were tested for efficacy in promoting colorectal cancer (CRC) screening (fecal occult blood test [FOBT], flexible sigmoidoscopy, or colonoscopy). All participants completed baseline interviews at the end of their usual service calls to the CIS, as well as short-term (6-month) and longer-term (14-month) telephone follow-up interviews. The study sample (n = 4,014) was restricted to English-speaking CIS callers 50 + years of age, who would be eligible for CRC screening at 14 months follow-up and did not call the CIS about CRC or CRC screening. Four experimental conditions were compared: a single untailored (SU) mailout of print material (the control condition); a single tailored (ST) mailout of print material; four (multiple) tailored (MT) mailouts of print materials spanning 12 months, all of which were tailored to information obtained at baseline; and four (multiple) retailored (MRT) mailouts also spanning 12 months, with retailoring of the print materials (mailouts 2, 3, and 4) based on updated information obtained from the 6-month follow-up interviews. Consistent with the main hypothesis of this trial, a significant linear trend across the SU, ST, MT, and MRT groups was found at 14 months (42%, 44%, 51%, and 48%, respectively, p = 0.05). Only for MT was there a significant difference compared with SU (p = 0.03) for the sample as a whole, while no differences were found for MT vs. MRT at 14 months. Significant moderator effects in the predicted direction were found among females, younger participants, and among those with a history of CRC screening, all of which involved the SU vs. MT MRT comparisons. Only among younger participants (ages 50-59) was there a difference between SU vs. ST at 14 months. Given these results, we conclude from this trial the following: (1) the MRT intervention failed to show added benefit beyond the MT intervention, (2) the significant intervention effects involving the MT and MRT conditions can be explained by tailoring and/or the longitudinal nature of both interventions, and (3) the most compelling evidence in support of tailoring was found for the ST condition among younger participants, where a significant need for interventions exists at the national level. Directions for future research are discussed in light of the results summarized above.

Lessons learned from community-based cancer screening intervention research

Behaviors associated with cancer screening have been the focus of intensive research over the past 2 decades, primarily in the form of intervention trials to improve screening based in both clinical and community settings. Meta-analyses and literature reviews have synthesized and organized the resulting literature. From the accumulated work, this review distilled lessons learned from cancer screening intervention research in community settings. The authors posed the question, "What do we know about the development of effective community-based interventions (the level of good over harm achieved in real-world conditions)?" Framed around the concept of focal points (the simultaneous combination of target population, behavioral objective, and setting for an intervention), 13 lessons were derived. One lesson was cross-cutting, and the other lessons addressed the three focal-point components and the major intervention categories (access-enhancing strategies, mass media, small media, one-on-one and small-group education, and combinations of these categories). To build more systematically on existing research, recommendations are made for new directions in basic behavioral and intervention research.

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.

Increasing attendance at colorectal cancer screening: testing the efficacy of a mailed, psychoeducational intervention in a community sample of older adults

This article describes a trial of a psychoeducational intervention designed to modify negative attitudes toward flexible sigmoidoscopy screening and thereby increase screening attendance. The intervention materials addressed the multiple barriers shown to be associated with participation in earlier studies. Adults ages 55-64 (N = 2,966), in a "harder-to-reach" group were randomized either to receive an intervention brochure or to a standard invitation group. Attitudes and expectations were assessed by questionnaire, and attendance at the clinic was recorded. Compared with controls, the intervention group had less negative attitudes, anticipated a more positive experience, and had a 3.6% higher level of attendance. These results indicate that psychoeducational interventions can provide an effective means of modifying attitudes and increasing rates of screening attendance.

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.

Effectiveness of a worksite intervention to reduce an occupational exposure: the Minnesota wood dust study

OBJECTIVES

This study assessed the effectiveness of an intervention to reduce wood dust, a carcinogen, by approximately 26% in small woodworking businesses.

METHODS

We randomized 48 businesses to an intervention (written recommendations, technical assistance, and worker training) or comparison (written recommendations alone) condition. Changes from baseline in dust concentration, dust control methods, and worker behavior were compared between the groups 1 year later.

RESULTS

At follow-up, workers in intervention relative to comparison businesses reported greater awareness, increases in stage of readiness, and behavioral changes consistent with dust control. The median dust concentration change in the intervention group from baseline to follow-up was 10.4% (95% confidence interval = -28.8%, 12.7%) lower than the change in comparison businesses.

CONCLUSIONS

We attribute the smaller-than-expected reduction in wood dust to the challenge of conducting rigorous intervention effectiveness research in occupational settings.

Promoting fecal occult blood testing in rural African American women

PURPOSE

The purpose of this experimental study was to test the effectiveness of a multiphasic culturally relevant intervention, delivered over a 1-year period to increase the rates of participation in fecal occult blood testing (FOBT) at the initial screening opportunity and at the 1-year follow-up screening opportunity among rural African American women.

DESCRIPTION OF STUDY

The study used a pretest/post-test design among African American women who attended senior citizen centers in a rural southern state. The centers were randomly assigned to the cultural and self-empowerment group, who received the five-phased intervention, the modified cultural group, who received phase I of the intervention only, or the traditional group, who served as the control group. Data were collected at the initial and 1-year follow-up screenings. Hemoccult kits were distributed, collected, and analyzed at no cost to the participants. Data were analyzed using descriptive statistics, repeated measures, and longitudinal models for binary outcomes.

RESULTS

Women in the cultural and self-empowerment group had a significantly higher rate of participation in FOBT than did those in the modified cultural group and the traditional group. The modified cultural group had a significantly higher rate of participation in FOBT than the did the traditional group. Predictors of participation in FOBT were the women's family history of colorectal cancer and the average number of visits to their healthcare provider.

CLINICAL IMPLICATIONS

Colorectal cancer screening and diagnostic testing opportunities should be offered consistently to women who visit their provider for routine, nonemergent office visits. As successful interventions to increase colorectal cancer screening are introduced into community settings, these interventions also should be tested within physicians' offices and other community agencies.

Feasibility of a tailored intervention to improve preventive care use in women

BACKGROUND

Women age 50 years and older are in need of multiple preventive health care services. Despite recent improvements in rates of delivery of preventive care services, especially within managed care organizations, substantial numbers of women are still being underscreened. Efforts to improve delivery of preventive care services have often focused on one outstanding service despite the fact that patients often are in need of many services.

METHODS

A total of 893 women age 50 to 55 years were mailed a self-administered survey to identify outstanding preventive health care service needs. Patients in need of three or more outstanding preventive health care services were identified from survey respondents to participate in a feasibility study evaluating a tailored, customized intervention called Tic Tac Health.

RESULTS

Five-hundred ninety-one women returned the survey (67%). Four-hundred forty-eight (76%) women were in need of one or more preventive health services; 92 (16%) were in need of three or more. Twenty-two patients (24%) completed the Tic Tac Health card. The women who completed the card were similar to those who did not.

CONCLUSIONS

Despite documented physician visits, presence of managed care health insurance, and a designated primary care provider, a significant number of women are still in need of multiple preventive health services. An intervention targeting multiple preventive health services was demonstrated to be both feasible and effective. Further evaluation via a randomized controlled trial should be conducted to determine if an intervention like Tic Tac Health would be an effective modality for improving rates of receipt of multiple preventive health care services.

Mediating factors in dietary change: understanding the impact of a worksite nutrition intervention

This report, based on 1,795 participants in the Next Step Trial, examines how a dietary intervention program affected mediating factors for dietary change. The model tested whether intervention increased predisposing (skills, knowledge, and beliefs) and enabling (social support and norms) factors for change and advanced participants into action and maintenance stages of change. The intervention significantly increased both predisposing factors for dietary change and the likelihood of moving into or remaining in action and maintenance stages of change. Changes in predisposing and enabling factors and stage of change at follow-up (regardless of stage at baseline) were associated with significant dietary change. Changes in mediating variables explained between 34% and 55% of the effects of the dietary intervention. These results support the value of measuring mediating factors as part of dietary intervention evaluations and suggest that interventions that target norms and eating environments in addition to skills and knowledge may further increase intervention effectiveness.