RETRACTED: Changes in soft drinks purchased by British households associated with the UK soft drinks industry levy: controlled interrupted time series analysis

Abstract Objective To determine changes in household purchases of drinks and confectionery one year after implementation of the UK soft drinks industry levy (SDIL). Design Controlled interrupted time series analysis. Participants Members of a panel of households reporting their purchasing on a weekly basis to a market research company (average weekly number of participants n=22 183), March 2014 to March 2019. Intervention A two tiered tax levied on manufacturers of soft drinks, announced in March 2016 and implemented in April 2018. Drinks with ≥8 g sugar/100 mL (high tier) are taxed at £0.24/L and drinks with ≥5 to <8 g sugar/100 mL (low tier) are taxed at £0.18/L. Drinks with <5 g sugar/100 mL (no levy) are not taxed. Main outcome measures Absolute and relative differences in the volume of, and amount of sugar in, soft drinks categories, all soft drinks combined, alcohol, and confectionery purchased per household per week one year after implementation of the SDIL compared with trends before the announcement of the SDIL. Results In March 2019, compared with the counterfactual estimated from pre-announcement trends, purchased volume of drinks in the high levy tier decreased by 155 mL (95% confidence interval 240.5 to 69.5 mL) per household per week, equivalent to 44.3% (95% confidence interval 59.9% to 28.7%), and sugar purchased in these drinks decreased by 18.0 g (95% confidence interval 32.3 to 3.6 g), or 45.9% (68.8% to 22.9%). Purchases of low tier drinks decreased by 177.3 mL (225.3 to 129.3 mL) per household per week, or 85.9% (95.1% to 76.7%), with a 12.5 g (15.4 to 9.5 g) reduction in sugar in these drinks, equivalent to 86.2% (94.2% to 78.1%). Despite no overall change in volume of no levy drinks purchased, there was an increase in sugar purchased of 15.3 g (12.6 to 17.9 g) per household per week, equivalent to 166.4% (94.2% to 238.5%). When all soft drinks were combined, the volume of drinks purchased did not change, but sugar decreased by 29.5 g (55.8 to 3.1 g), or 9.8% (17.9% to 1.8%). Purchases of confectionery and alcoholic drinks did not change. Conclusions Compared with trends before the SDIL was announced, one year after implementation, the volume of soft drinks purchased did not change. The amount of sugar in those drinks was 30 g, or 10%, lower per household per week—equivalent to one 250 mL serving of a low tier drink per person per week. The SDIL might benefit public health without harming industry. Trial registration ISRCTN18042742.


Supplementary material B
The model specification is given by: the fall in purchases in the weeks immediately after Christmas; and the increase in confectionery purchases seen at Easter, for toiletries these were set to 0. To adjust for temperature-related trends in drink consumption the average UK monthly temperature was included in the intervention group with the average study period temperature used for toiletries . 5Quadratic functions of announcement trends were included where they improved model fit -assessed using likelihood ratio tests.Stationary was examined using augmented Dickey-Fuller tests. 41Autocorrelation between preceding time points was examined using autocorrelation and partial-autocorrelation plots.An appropriate autocorrelation structure was determined and then compared to alternative models using likelihood ratio tests.Visual inspection of the data suggested no additional benefit would be gained from including polynomial terms.

Supplementary material C
Supplementary . .
*Give information separately for cases and controls in case-control studies and, if applicable, for exposed and unexposed groups in cohort and cross-sectional studies.Note:

Table 2a :
Modelled level and trend changes in volume of drinks (ml) and confectionery (g) purchased per household per week (95% CI) in relation to theUK SDIL, March 2014 -March 2019 † Trend 2 , Bold indicates a significant difference at the 95% confidence interval level.Supplementary

Table 2b :
Modelled level and trend changes in sugar in drinks (ml) and confectionery (g) purchased per household per week (95% CI) in relation to theUK SDIL, March 2014 -March 2019 † Trend 2 , Bold indicates a significant difference at the 95% confidence interval level.

6 (-20.7,-2.5) -19.7 (-33.3,-6.0)
Trend 2 , Bold indicates a significant difference at the 95% confidence interval level.The levy liable drinks category is a combination of high tier, low tier and no levy drinks.aMilkcomprisesdrinks in the following categories: semi-skimmed; specific low fat % milk (e.g.1% fat milk); whole milk; buttermilk; modified milk; other milk; other non-cows milk; rice drink; soya milk.Skimmed milk is excluded from all analysis in this paper due to missing data.Supplementary Table3b: Absolute and relative change in volume of, and sugar in, all drinks and confectionery (g) purchased per household (95% CI) per week in relation to theUK SDIL, March 2014-March 2019