Obesity Prevention and Control: Worksite Programs

Research Gaps

What are Research Gaps?

Prior to and during the literature review and data analysis, the review team and the Community Preventive Services Task Force attempt to address the key questions of what interventions work, for whom, under what conditions, and at what cost. Lack of sufficient information often leaves one or more of these questions unanswered. The Community Guide refers to these as "research gaps." Research gaps can be pulled together in the form of a basic set of questions to inform a research agenda for those in the field or can be a more extensive narrative that weaves mention of gaps into a discussion generated by findings from the review.

Identified Research Gaps

Although we found evidence that worksite programs targeting nutrition and physical behaviors confer modest, positive, weight-related benefits, important research questions remain. One of our initial review questions was only partially answered: which employee populations benefit the most from worksite health promotion interventions targeted at weight? Weight status varies considerably among employee populations. Reporting individual weight measure for employees from baseline to follow-up is not feasible in large occupational health studies. Instead, measurement of weight change in the studies we reviewed was usually presented as group mean change in BMI, pounds, kilograms, or percent body fat. Thus, we could not determine if those at greatest risk (i.e., overweight or obese) benefited more or less. Nor could we determine if a few employees lost a large amount of weight or if many employees lost small amounts. In addition to measuring mean weight change, it would also be useful to learn what percent of participants had clinically meaningful weight loss (i.e., >5% or >10 % body weight loss). Also, reporting changes in the prevalence of overweight and obesity in the employee population as a result of the intervention would provide information about intervention effects at the population-level. Highly effective interventions that reach only a small percent of the population will likely not affect the prevalence.

Forty percent the studies lacked information to determine differential effects according to blue or white collar job status. Those that did report occupational status included predominantly white collar workers. Race and ethnicity data were also limited.

A variety of worksite settings were represented in this review, which lends to the generalizability of the findings. Information on the feasibility of implementing programs across small to very large worksite settings, however, was hampered by missing workplace size data in 64% of the studies. We found no association between program effectiveness and focus of the program (e.g., CVD risk reduction, weight loss, physical fitness) or behavioral focus (diet or physical activity). Because the majority of programs used behavioral plus informational strategies, it was difficult to contrast program components with respect to effectiveness. Questions remain about the effect on employee weight status when implementation of environmental change (e.g., providing easy access to affordable, healthy foods, or modifying the physical environment to encourage physical activity) and employer policy strategies (health insurance incentives, contribution to gym membership fees, etc.) is included.

One third of the RCTs provided insufficient statistical information to allow meta-analytic pooling of effects. Only a few reported intention to treat analysis. Reporting on intervention intensity, duration, and fidelity was often ambiguous. Future studies will contribute more to the empirical knowledge base if they follow the CONSORT guidelines for reporting RCTs and TREND guidelines for reporting non-randomized studies.