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Table 2 Mean household beverage expenditure in Tonga before and after a sweetened-beverage tax

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

Outcome   2009 (95% CIs) 2015/16 (95% CIs) Absolute difference (t-test 95% CIs) % change (95% CI) p-value
Purchasing prevalence (% households) All beverages 72.3 (69.6 to 74.9) 80.9 (78.4 to 83.3) 8.6 (5.0 to 12.2) 11.9 (6.6 to 17.3) < 0.001
Soft drinks 51.3 (48.3 to 54.3) 40.4 (37.3 to 43.5) −10.9 (− 15.2 to −6.5) −21.2 (−28.7 to − 13.4) < 0.001
Milk 29.9 (27.3 to 32.4) 44.5 (40.7 to 48.4) 14.6 (10.0 to 19.3) 49.0 (31.3 to 67.8) < 0.001
Bottled water 10.4 (8.7 to 12.1) 35.0 (31.5 to 38.4) 24.6 (20.7 to 28.4) 236.5 (176.3 to 306.0) < 0.001
Mean expenditure (2015/16 T$ /person/year) All beverages 83.8 (73.6 to 94.0) 116.0 (100.6 to 131.4) 32.2 (13.7 to 50.7) 38.4 (14.4 to 64.5) 0.001
Soft drinks 37.9 (31.1 to 44.7) 29.6 (22.5 to 36.8) −8.2 (−18.1 to 1.6) −21.8 (−44.1 to 3.2) 0.102
Milk 22.7 (19.7 to 25.8) 35.4 (28.7 to 42.2) 12.7 (5.2 to 20.1) 55.7 (20.6 to 93.6) 0.001
Bottled water 6.0 (3.4 to 8.6) 26.6 (20.9 to 32.3) 20.5 (14.3 to 26.8) 341.1 (155.7 to 621.0) < 0.001
All food and beverages 2500 (2310 to 2680) 2150 (2020 to 2280) − 344 (− 573 to − 115) −13.8 (−21.9 to − 5.2) 0.003
Beverage expenditure as a proportion of household food budget (%) All 3.20 (2.94 to 3.45) 5.41 (4.61 to 6.21) 2.22 (1.38 to 3.06) 69.4 (41.5 to 98.3) < 0.001
Soft drinks 1.39 (1.24 to 1.55) 1.32 (1.07 to 1.58) −0.07 (−0.37 to 0.22) −5.2 (−25.7 to 16.5) 0.633
Milk 0.87 (0.77 to 0.97) 1.68 (1.44 to 1.93) 0.82 (0.55 to 1.08) 94.2 (59.4 to 131.7) < 0.001
Bottled water 0.21 (0.14 to 0.28) 1.31 (0.78 to 1.85) 1.11 (0.56 to 1.65) 532.5 (230.7 to 906.0) < 0.001
Beverage expenditure per person as a proportion of equivalised income (%) All 0.87 (0.75 to 1.00) 1.20 (1.02 to 1.39) 0.33 (0.11 to 0.56) 38.3 (10.5 to 69.0) 0.004
Soft drinks 0.39 (0.33 to 0.45) 0.32 (0.23 to 0.42) −0.07 (−0.18 to 0.05) − 17.0 (−44.5 to 12.8) 0.267
Milk 0.23 (0.19 to 0.27) 0.33 (0.28 to 0.38) 0.10 (0.04 to 0.17) 43.2 (12.0 to 79.1) 0.002
Water 0.07 (0.00 to 0.13) 0.23 (0.18 to 0.29) 0.16 (0.08 to 0.25) 234.3 (−63.5 to 1072.1) < 0.001
Estimated quantity of beverages acquired (kg/person/year) All   56.1 (46.6 to 65.5)    
Soft drinks   10.2 (7.9 to 12.4)    
Milk   10.3 (8.3 to 12.2)    
Bottled water   27.5 (20.7 to 34.4)    
  1. The 2009 expenditure findings were increased to adjust for inflation between 2009 and 2015/16 (12.4% increase, using CPI data from the Department of Statistics). P-values were calculated using the t-test for the difference between two means on an absolute scale. Absolute changes were expressed as a percentage (%) change by dividing the absolute change and its confidence intervals by the 2009 outcome value. The 2013 Tonga SB tax applied to soft drinks. Figures for quantity of beverages were estimated from price, available only for 2015/16.The complex survey design was taken into account in analysis to ensure findings represent the national Tongan population. Data source: Tonga Department of Statistics, Household Income and Expenditure Surveys