Effectiveness of a multi-strategy intervention in increasing the implementation of vegetable and fruit breaks by Australian primary schools: a non-randomized controlled trial

Longitudinal studies have shown that intake of vegetables and fruit in childhood can reduce the subsequent development of chronic diseases, including cardiovascular disease and cancers [1‐3]. Moreover, a diet high in vegetables and fruit provides immediate nutritional benefits for children as well as protection against obesity [4, 5] and some respiratory diseases [6]. Despite this, children in many developed countries fail to consume adequate daily quantities of vegetables and fruit [7‐9]. As a consequence, increasing children’s consumption of vegetables and fruit is a recognized public health priority [10], with the population wide implementation of effective programs promoting such behavior being a recommended chronic disease prevention strategy [10‐12].

One recommended setting for promoting children’s vegetable and fruit consumption on a population-wide basis is schools [13]. Systematic reviews have consistently found that school-based vegetable and fruit programs are efficacious, and increase children’s daily vegetable and fruit consumption [13‐20]. Consequently, a number of vegetable and fruit programs and schemes have been developed for implementation in schools. For example the United Kingdom [9], United States [21], Norway [22] and New Zealand [23] have school vegetable and fruit schemes which provide all or some students with a fully or partially subsidized piece of vegetable or fruit to consume each day at school. As an alternative to such distribution programs, Australian schools have been encouraged to implement a vegetable and fruit break program that provides a time in class for children to consume a piece of vegetable or fruit they have brought from home [24].

There have been calls for rigorous implementation research to identify the strategies that are effective in supporting population-wide implementation of such programs so that they benefit the health of the community [25]. The need for such research is illustrated by the findings of a recent update of an Agency for Health Care Policy and Research review published in 2010. The review of interventions in community based settings, including schools, primarily sought to evaluate the effectiveness of implementation or dissemination interventions on policies or programs promoting healthy eating, physical activity, sun protection, or preventing tobacco use. Implementation and dissemination studies were defined as those that evaluated the “effectiveness of efforts that enable the widespread use of an evidence-based intervention by the target population and its successful integration within a particular setting”. The review identified just four school based interventions to improve the adoption of healthy eating policies or practices in schools and none targeted the adoption of vegetable and fruit initiatives specifically [26].

However, theoretical frameworks regarding organizational change more broadly [27, 28] and evidence from reviews and trials assessing the efficacy of implementation strategies addressing other health issues in schools [29‐32], suggest that multi-strategy interventions that; develop the support of key opinion leaders, provide program materials and training, monitor program implementation, and provide technical support and implementation feedback, are most likely to be effective in changing service delivery practice. In the above mentioned review of implementation interventions in community settings [26], those that have adopted a multi-strategy approach have reported a change in prevalence of program implementation of between 50 %-78 %. However, only a few of these studies have targeted a large number (>100) of schools [33‐36] or utilized evaluation designs incorporating comparison groups [34, 35, 37], limiting the ability to infer causality.

In order to achieve the potential public health benefits of school based vegetable and fruit programs, further evidence is required regarding the strategies that are effective in facilitating the implementation of such programs across an entire population of schools. In addition, as the implementation of programs by schools has been reported to be associated with school characteristics such as number of students, and socioeconomic and geographic characteristics, further evidence is required regarding the effectiveness of such strategies for different types of schools [38, 39].

In this context we undertook a study to assess the effectiveness of a multi-strategy intervention, relative to information-based support, in increasing the implementation of an in-class vegetable and fruit break by a population of primary schools.

To our knowledge, this is the first controlled evaluation of an intervention to facilitate the implementation of a vegetable and fruit program across a large number of schools. The findings suggest that the multi-strategy intervention involving leadership support, staff training and telephone follow-up support, was effective in increasing the uptake of vegetable and fruit breaks in schools compared to more minimal, information-based support. These findings provide support for the use of a multi-strategic intervention approach in facilitating a large number of schools to implement vegetable and fruit programs across a large and diverse geographic region.

The effect size reported in the trial (approximately 15 % relative to comparison schools) was consistent with those reported in controlled trials of interventions designed to assist large numbers of schools implement health promotion programs generally (13 %-45 %) [31, 34, 35, 49, 50]. On a population wide basis, a 15 % increase in the number of schools implementing vegetable and fruit programs is likely to represent a meaningful contribution to improving public health nutrition. For example, in this trial, a 15 % increase resulted in an additional 58 schools implementing a vegetable and fruit break in most or all classes. Assuming an average school size of 250 students, almost 15,000 additional children may have benefitted from the program.

Despite the significant finding, a number of opportunities exist to further enhance the intervention. First, although 70 % of schools received training, in most schools only a single staff member was trained. Due to poor promotion and limited school access to facilities videoconference training was not attended by staff from any school. As the knowledge, skills and support of all staff are important predictors of program implementation [29, 51] additional strategies targeting training of multiple staff, for example as part of staff orientation or routine professional development workshops [36, 52, 53], have the potential to increase program implementation. Second, while 95 % of schools received the initial follow-up CATI support call, more intensive and prolonged follow-up support has been suggested to yield improved rates of program adoption [29, 53]. Third, less than 30 % of schools reported receiving the tailored school implementation feedback report. Anecdotal evidence indicated that mailed resources were frequently misplaced or unopened at schools. Further development and analysis of the most effective format and delivery of performance feedback reports is required to maximize the previously reported positive impact of such a strategy on program implementation [29, 31].

A number of the study characteristics should be considered when interpreting the study findings. Given the challenges of random assignment in large complex public health interventions [54], the trial utilized a quasi-experimental design. Nonetheless, the internal validity of the trial would have been strengthened had a random experimental evaluation design been employed. The intervention was undertaken as part of a larger multi-setting child obesity prevention program [40]. The existence of the broader program may have enhanced the salience of obesity prevention efforts in the intervention community and pre-disposed schools to the implementation of obesity prevention programs such as vegetable and fruit breaks. The trial was also reliant on the self-reported existence of vegetable and fruit breaks collected as part of a telephone survey. Whilst attempts were made to validate the measure. The use of alternative survey modalities, such as the web may reduce the risk of social desirable responding [55], and the use of direct observation would represent a more objective assessment of program adoption. Additionally, schools lost to follow-up were significantly different from those that completed the survey with respect to school type, size and geographic location. This may have introduced bias due to selective non-participation. The intervention effect size, however, was similar across subgroups suggesting that risk of such bias is likely to be minimal. Finally, the intervention encouraged schools to identify strategies to ensure that all children participated in the vegetable and fruit break. While data regarding student participation was not collected in the trial, anecdotally, Principal’s frequently reported school wide participation by all students through school provision of vegetable or fruits to the small number of children unable to bring these foods from home, or by cutting up the vegetables and fruit provided by students and sharing it with all class members.

The study provides novel information for public health policy makers and practitioners regarding strategies to facilitate the implementation of health promotion programs broadly, and vegetable and fruit break programs specifically. Given that maintenance of the intervention effect is expected to decrease over time [29, 56], longer-term follow-up of these schools appears warranted in order to determine whether the intervention impact is sustained. Furthermore, examination of the cost effectiveness of such strategies in achieving program implementation may assist policy makers and practitioners to most effectively allocate scarce health resources to improve the health of the community.