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Effectiveness of a no-cost-to-workers, slip-resistant footwear program for reducing slipping-related injuries in food service workers: a cluster randomized trial (Bell, Collins & Chiou 2019)

Absence of conflict of interest.

Citation

Bell, J. L., Collins, J. W., & Chiou, S. (2019). Effectiveness of a no-cost-to-workers, slip-resistant footwear program for reducing slipping-related injuries in food service workers: a cluster randomized trial. Scandinavian Journal of Work, Environment & Health, 45(2), 194–202.

Highlights

  • The report's objective was to examine the impact of a no-cost-to-workers, slip-resistant footwear (SRF) program on slip-related work injuries. 

  • This study is a cluster-level randomized controlled trial that assigned school districts to use either the no-cost-to-workers SRF program (i.e., the treatment group) or a business-as-usual voluntary SRF program that required workers to buy their own SRF (i.e., the control group). The study used a logistic regression statistical model to compare the outcomes of school food service workers assigned to treatment and comparison groups, using electronic administrative data collected and maintained by the contracted food service company that employed the workers. 

  • The study reported that workers in the intervention group were significantly less likely to have slip-related injuries than workers in the comparison group.   

  • The quality of the evidence in this study is high because it was based on a well-implemented randomized controlled trial. This means we are confident that the estimated effects are attributable to the no-cost-to-workers slip-resistant footwear program and not to other factors. 

Intervention Examined

No-cost-to-workers slip-resistant footwear (SRF) program

Features of the Intervention

Slip-resistant footwear is designed to reduce slipping of the foot on the floor surface and prevent injury. Slips and falls are the second most frequent work-related injury in the U.S. The study examines a slip-resistant footwear (SRF) program that offered free commercially available SRF to school food service workers. Workers ordered SRF from their employer and had a choice of seven different styles of the same brand that had the same sole pattern. Onsite managers monitored the sole wear of the SRFs and helped with re-ordering new SRF after six months of full-time wear, or as needed.  

Features of the Study

This study is a cluster-randomized controlled trial and examines how a no-cost-to-workers, slip-resistant footwear (SRF) program affects slipping-related injuries of food service workers from 226 school districts' kindergarten through twelfth grade food service operations. School districts were randomly assigned to treatment and comparison groups, so that all workers in the same district received the intervention or continued with business as usual. New workers could join the study at the time of hire.  

The sample included 226 school districts and 16,949 food service workers in the Northeast, South Central and Great Lakes West regions. The workers in the sample were overwhelmingly female and included a large group of workers aged 55 and older. The treatment group consisted of 118 school districts (7,490 workers) and the comparison group consisted of 98 school districts (6,647 workers).  

The treatment group received the intervention, while the comparison group received business as usual practices including a slip prevention program. In the comparison group’s voluntary slip prevention program, workers were encouraged to use SRF, but were required to purchase their SRF on their own. 

The authors used a statistical model to compare the outcomes of treatment and comparison group members. The study used administrative claims data from the food service company's workers compensation injury claims database on all claims related to slip, trip, and fall injuries. Data for the follow-up period included claims from August 1, 2011 to December 31, 2013. 

Study Sites

The study was conducted 226 school districts in the US that had K-12th grade food operations using a specific partner company. Study sites were located in the three geographic business units that included school districts in the Northeast, South Central, and Great Lakes West regions. 

Findings

Health and safety  

  • The study found a statistically significant reduction in the number of slip-related injuries for workers in treatment group school districts (i.e., school districts that offered the no-cost-to-workers SRF program). After the implementation of the no-cost-to-workers SRF program, the number of slip-related work injuries per 10,000 worker months was lower in the treatment group than that of the control group. The study’s logistic regression model found that the trend of declining slip-related injuries for the treatment group in the follow-up period was statistically different than the trend of slip-related injuries in the follow-up period for the control group.

Considerations for Interpreting the Findings

The study had a dynamic sample of workers through the duration of the study. A total of 16,949 unique workers were employed over the duration of the study. There were joiners into both groups as school districts hired more food service workers and food service workers also left. Approximately 850 workers in the treatment group and 600 workers in the control group joined the study after the start of the intervention. Ten school districts (7 treatment and 3 comparison) provided baseline data, but were not included in the follow up data. 

During analysis, the study controlled for age because older workers aged 55 years and older were at greater risk for injury. 

Causal Evidence Rating

The quality of causal evidence presented in this report is high because it was based on a well-implemented randomized controlled trial. This means we can be confident that any estimated effects would be attributable to the SRF program and not to other factors. 

Reviewed by CLEAR

February 2022