Clinical trial NCT03252158: Altering the Availability of Healthier vs. Less Healthy Items in Vending Machines
Official title: Impact of the Availability of Healthier vs. Less Healthy Foods and Beverages on Purchasing From Hospital Vending Machines
Study type: INTERVENTIONAL
Overall status: COMPLETED
Phase: NA
Conditions: Healthy Diet
Lead sponsor: University of Cambridge
Sponsor class: OTHER
Collaborators: name: Oxford University Hospitals NHS Trust
First posted: 2017-08-17
Enrollment: 10
Sex: ALL
Standard ages: CHILD
ADULT
OLDER_ADULT
Accepts healthy volunteers: yes
Allocation: RANDOMIZED
Intervention model: CROSSOVER
Intervention model description: An adapted multiple treatment reversal design will be used, in which the number of slots containing (i) less healthy items and (ii) healthier items are altered over eight 4-week periods.

Vending machines will be randomly allocated to one of two groups: (1) decreasing less healthy foods first or (2) decreasing healthier foods first.
Primary purpose: BASIC_SCIENCE

Brief summary: Background: While there is some evidence that increasing the range of healthier foods and drinks and/or decreasing the range of less healthy options may increase healthier choices, more work is needed to establish the reproducibility of any effect. The current study aims to investigate the impact of altering the availability of healthier and less healthy foods and cold beverages in hospital vending machines.

Methods: An adapted multiple treatment reversal design will be used, in which all standard vending machines serving snack foods and/or cold beverages in one hospital in England change the number of slots containing (i) less healthy items and (ii) healthier items over eight 4-week periods. Changes will take place in a two-step process whereby decreases are implemented in a separate study period prior to increases in the contrasting food group. Following a 4-week baseline period, all vending machines will be standardised to have 75% healthier drinks and/or 25% healthier snacks (study period 1). Vending machines (n=9) will be randomly allocated to the order in which they: (1) decrease less healthy foods and increase healthier foods or (2) decrease healthier foods and increase less healthy foods (study periods 2\&3 and 5\&6). After each decrease-increase pair, machines will return to the standardised 75% healthier drinks and 25% healthier snacks (study periods 4 and 7). Sales data will be obtained via records of machine restocking.

Planned Analysis: The impact of the availability intervention will be assessed in separate linear mixed models for cold drinks and snacks, examining the impact on total energy (kcal) purchased, per restocking interval, with random effects for vending machine.


Eligibility criteria: Inclusion Criteria:

* All vending machines at one UK hospital selling standard-fare (i.e. not healthier alternatives) cold beverages and snack foods

Exclusion Criteria:

* Healthier alternative vending machines; vending machines selling hot drinks or meals

Primary outcomes:
measure: Energy purchased
timeFrame: Restocking interval (between 2-4 days; restocking occurs on set weekdays for each machine, to match usual restocking)
Secondary outcomes:
measure: Number of items sold
timeFrame: Restocking interval (between 2-4 days; restocking occurs on set weekdays for each machine, to match usual restocking)
measure: Energy purchased (healthier alternative machines)
timeFrame: Restocking interval (between 2-4 days; restocking occurs on set weekdays for each machine, to match usual restocking)
measure: Number of items sold (healthier alternative machines)
timeFrame: Restocking interval (between 2-4 days; restocking occurs on set weekdays for each machine, to match usual restocking)
Other outcomes:
Locations:
city: Cambridge
country: United Kingdom
facility: University of Cambridge
state: Cambridgeshire
Study officials:
affiliation: University of Cambridge
name: Rachel Pechey, PhD
role: PRINCIPAL_INVESTIGATOR
References: