Change in non-alcoholic beverage sales following a 10-pence levy on sugar-sweetened beverages within a national chain of restaurants in the UK: interrupted time series analysis of a natural experiment.
BACKGROUND
This study evaluates changes in sales of non-alcoholic beverages in Jamie's Italian, a national chain of commercial restaurants in the UK, following the introduction of a £0.10 per-beverage levy on sugar-sweetened beverages (SSBs) and supporting activity including beverage menu redesign, new products and establishment of a children's health fund from levy proceeds.


METHODS
We used an interrupted time series design to quantify changes in sales of non-alcoholic beverages 12 weeks and 6 months after implementation of the levy, using itemised electronic point of sale data. Main outcomes were number of SSBs and other non-alcoholic beverages sold per customer. Linear regression and multilevel random effects models, adjusting for seasonality and clustering, were used to investigate changes in SSB sales across all restaurants (n=37) and by tertiles of baseline restaurant SSB sales per customer.


RESULTS
Compared with the prelevy period, the number of SSBs sold per customer declined by 11.0% (-17.3% to -4.3%) at 12 weeks and 9.3% (-15.2% to -3.2%) at 6 months. For non-levied beverages, sales per customer of children's fruit juice declined by 34.7% (-55.3% to -4.3%) at 12 weeks and 9.9% (-16.8% to -2.4%) at 6 months. At 6 months, sales per customer of fruit juice increased by 21.8% (14.0% to 30.2%) but sales of diet cola (-7.3%; -11.7% to -2.8%) and bottled waters (-6.5%; -11.0% to -1.7%) declined. Changes in sales were only observed in restaurants in the medium and high tertiles of baseline SSB sales per customer.


CONCLUSIONS
Introduction of a £0.10 levy on SSBs alongside complementary activities is associated with declines in SSB sales per customer in the short and medium term, particularly in restaurants with higher baseline sales of SSBs.
['Cornelsen|Laura|L|', 'Mytton|Oliver T|OT|http://orcid.org/0000-0003-3218-9912', 'Adams|Jean|J|', 'Gasparrini|Antonio|A|', 'Iskander|Dalia|D|', 'Knai|Cecile|C|', 'Petticrew|Mark|M|', 'Scott|Courtney|C|', 'Smith|Richard|R|', 'Thompson|Claire|C|', 'White|Martin|M|', 'Cummins|Steven|S|']
D001628:Beverages D002253:Carbonated Beverages D002648:Child D003132:Commerce D006801:Humans D065186:Interrupted Time Series Analysis D012147:Restaurants D012959:Socioeconomic Factors D013549:Sweetening Agents D006113:United Kingdom
sugar-sweetened beverages natural experiment diet interrupted-time series sugar tax