Randomized trial of planning tools to reduce unhealthy snacking: Implications for health literacy

Abstract

ObjectiveGuidance to address health literacy often focuses on health education rather than tools to facilitate action, despite action being important for self-management. This study evaluated an online intervention informed by health literate design principles and behavior change theory to reduce unhealthy snacking.Methods440 participants were recruited online and randomized to an intervention: 1) Health-literate action plan (guided implementation intention); 2) Standard action plan (self-guided implementation intention); 3) Education (healthy snacking fact-sheet). The primary outcome was self-reported unhealthy snacking. Follow-up was at 1 month.Results373 participants (84.8%) completed follow-up. Half the sample had adequate health literacy (52%), and the other half had low (24%) or possibly low (25%) health literacy, as measured by Newest Vital Sign (NVS). At follow-up, lower health literacy was associated with more unhealthy snacks and there was no overall difference between intervention groups. However, participants with lower health literacy who used the health-literate action plan reported less unhealthy snacking compared to the standard action plan; the reverse was true for those with higher health literacy scores (b = 1.7, p = 0.03). People scoring 2 points below the mean NVS (M = 3.4, SD = 2.0) using the health-literate action plan reported eating 8 fewer serves of unhealthy snacks, whereas people scoring 2 points above the mean NVS reported eating 6 more serves of unhealthy snacks using the same tool.ConclusionsThese findings suggest that the universal precautions approach currently recommended for health information may be less effective for facilitating action than tailoring to health literacy level.Trial registrationANZCTR identifier: ACTRN12617001194358.

Effects of health literacy, screening, and participant choice on action plans for reducing unhealthy snacking in Australia: A randomised controlled trial

“…Estimates of expected effect size and retention were based on previous work exploring the effects of action plans on unhealthy snacking [ 23 ]. A sample size estimate of 500 in each allocation arm was based on requiring 80% power using a 5% significance level to detect a small main effect (Cohen’s f ratio effect size = 0.08, as in the previous study) in a univariate ANOVA comparing the 3 allocation method arms.…”

“…Our recent randomised controlled trial (RCT) addressed both of these gaps in the literature [ 23 ]. We evaluated the impact of applying health literacy principles to an online action plan to reduce self-reported unhealthy snacking over a 4-week period.…”

“…This was compared to a ‘standard’ action plan that asked participants to formulate their own free-text plans, affording greater potential for personalisation. The results showed that the effectiveness of each plan depended on the participant’s health literacy: people with lower health literacy reported consuming fewer unhealthy snacks at follow-up when they had used the literacy-sensitive action plan, whereas people with higher health literacy reported consuming fewer unhealthy snacks using the ‘standard’ action plan [ 23 ].…”

“…To achieve our second aim, we evaluated 3 alternative methods of allocating participants to an action plan: random allocation, screening for low health literacy, or allowing the participant to choose. Screening for health literacy is an obvious option given the results of our previous study [ 23 ]. However, health literacy assessment may also increase participant burden and reduce engagement with the intervention.…”

Evaluation of the Choosing Wisely Australia 5 Questions resource and a shared decision-making preparation video: protocol for an online experiment

“…Health literacy will be assessed by the Newest Vital Sign (NVS),28 with participants categorised as inadequate (score 0–3 on NVS) or adequate literacy (score 4–6 on NVS). The NVS has been used in other online studies,29 and is an objective, performance-based measure of health literacy skills. We will also administer a single-item measure of self-reported health literacy for the purposes of describing the sample.…”