Equity of expenditure changes associated with a sweetened-beverage tax in Tonga: repeated cross-sectional household surveys

Abstract

Background The aim of this study was to examine changes in beverage expenditure patterns before and after a T$0.50/L sweetened-beverage (SB) excise was introduced in Tonga in 2013, by household income, household age composition and island of residence. Methods Two cross-sectional surveys involved households being randomly sampled (the Household Income and Expenditure Surveys in 2009 (n = 1982) and 2015/16 (n = 1800)). Changes in soft drink (taxed), bottled water, and milk (both untaxed) expenditure were examined namely: (i) prevalence of households purchasing the beverage; (ii) average expenditure per person (inflation-adjusted); (iii) expenditure as a proportion of household food budget; and (iv) expenditure per person as a proportion of equivalised income. Results The pattern found was of decreases in all soft drink expenditure outcomes and these appeared to be greater in low-income than high-income households for purchasing prevalence (− 30% and − 25% respectively, t-test p = 0.98), per-capita expenditure (− 37% and − 34%, p = 0.20) and food budget share (− 27% and − 7%, p = 0.65), but not income share (− 6% and − 32%, p = 0.71). The large expenditure increases in bottled water appeared to be greater in low-income than high-income households for purchasing prevalence (355 and 172%, p = 0.32) and food budget share (665 and 468%, p = 0.09), but greater in high-income households for per-capita expenditure (121 and 373%, p < 0.01) and income share (83 and 397%, p = 0.50). Conclusions The sweetened-beverage tax was associated with reduced soft drink purchasing and increased bottled water expenditure. Low-income households appeared to have slightly greater declines in soft drink expenditure.

The Impact of Sugar-Sweetened Beverage Taxes by Household Income: A Multi-City Comparison of Nielsen Purchasing Data

“…We found one difference in our analysis of bottled water purchasing, which suggested that lower-income households might be more likely to switch to bottled water than higher-income households in response to an SSB tax. This finding was similar to results based on a study of SSB and bottled water purchases in France [ 34 ] and in Tonga [ 35 ]. While it is possible that more households generally are purchasing bottled water over time, this result was specific to Philadelphia’s tax structure.…”

Associations between trajectories of obesity prevalence in English primary school children and the UK soft drinks industry levy: An interrupted time series analysis of surveillance data

“…This also adds to the growing international evidence that SSB taxes may reduce inequalities in diet-related health outcomes. For example, some studies from other countries have shown that lower-income households were more likely to reduce their purchases or intake of sugar from SSBs following introduction of SSB taxes [ 36 , 50 , 51 ], although this is not always the case [ 22 , 52 , 53 ].…”

Associations between trajectories of obesity prevalence in English primary school children and the UK soft drink industry levy: an interrupted time series analysis of surveillance data

“…This also adds to the growing international evidence that SSB taxes may reduce inequalities in diet-related health outcomes. For example, some studies from other countries have shown that lower income households were more likely to reduce their purchases or intake of sugar from SSBs following introduction of SSB taxes [28,46,47] although this is not always the case [48][49][50].…”