Table 1

Baseline characteristics and group allocation by ethnicity, income and education, and loss to follow-up in during 6-month intervention phase

EthnicityHousehold incomeEducational qualifications*All study participants
MāoriPacificEuropean/other<NZ$60 000>NZ$60 000Declined/missingNone/secondaryTertiary/trade/other
Randomised, n (%)248 (23)101 (9)755 (68)576 (52)463 (42)65 (6)567 (51)535 (48)1104
Baseline demographics
Age in years, mean±SD37±1138±1047±1345±1542±1043±1344±1445±1244±13
Female, n (%)225 (91)88 (87)631 (84)501 (87)387 (84)56 (86)499 (88)444 (83)944 (86)
Baseline shopping characteristics
No. of other supermarkets from which household food is bought in average month, n (%) (χ2 p values: <0.01 ethnicity and income; 0.81 educational qualifications)
058 (24)12 (12)135 (18)124 (22)76 (16)5 (8)108 (19)97 (18)205 (18)
195 (38)35 (35)329 (44)250 (43)185 (40)24 (37)231 (41)228 (43)459 (42)
2 or more95 (38)54 (53)291 (38)202 (35)202 (44)36 (55)228 (40)210 (39)440 (40)
Other types of food outlets from which household food is also bought in an average month, n (%)
Takeaway bars/shops182 (73)75 (75)487 (65)355 (62)347 (75)42 (65)388 (69)354 (66)744 (67)
Dairy or service station137 (55)65 (65)241 (32)221 (39)185 (40)37 (57)236 (42)206 (39)443 (40)
Markets130 (52)69 (69)235 (31)229 (40)170 (37)35 (54)215 (38)217 (41)434 (39)
Fruit and vegetable shop148 (60)55 (55)243 (32)255 (45)155 (33)36 (55)235 (42)210 (39)446 (40)
Superettes/convenience84 (34)53 (52)132 (18)137 (24)100 (22)32 (49)142 (25)126 (24)269 (24)
Knowledge about nutrition, food and healthy eating, n (%) (compared with options of ‘nothing’ and ‘a little’)
‘Moderate’ or ‘a lot’189 (76)82 (81)667 (88)475 (82)406 (88)57 (88)446 (79)490 (92)938 (85)
Nutrient purchases, mean±SD
Saturated fat (% of energy)15.7±5.114.1±4.514.4±3.814.8±4.314.4±3.914.5±6.014.8±4.314.4±4.214.6±4.2
Food purchases (kg/week), mean±SD
All foods11.3±8.849.87±7.3414.53±7.7512.43±7.4715.01±8.5910.96±8.4713.48±8.4213.39±7.8313.44±8.13
Healthier discounted foods5.03±4.194.39±3.458.27±4.876.23±3.948.67±5.465.81±5.36.93±4.827.57±4.937.24±4.88
Fruit and vegetables3.6±3.082.97±2.545.25±3.364.15±2.785.48±3.773.92±3.624.5±3.274.92±3.414.70±3.35
Group allocation, n (%)
Price discounts62 (23)24 (9)189 (69)144 (52)116 (42)15 (6)138 (50)137 (50)275
Tailored nutrition education62 (23)25 (9)187 (68)142 (52)115 (42)17 (6)138 (50)135 (49)274
Price plus education61 (22)27 (10)189 (68)144 (52)116 (42)17 (6)152 (55)125 (45)277
Control63 (23)25 (9)190 (68)146 (53)116 (42)16 (6)139 (50)138 (50)278
Loss to follow-up in intervention phase
Data for 0–6 months§, n (%)207 (20)85 (8)736 (72)533 (52)441 (43)54 (5)523 (51)503 (49)1028
No data 0–6 months, n (% of sample)41 (17)16 (16)19 (3)43 (7)22 (5)11 (17)44 (8)32 (6)76 (7)
  • * Educational qualifications data missing for one person in the nutrition education group and one person in the control group.

  • The sum of healthier and less healthy products is less than the total for all products because some foods not directly relevant to trial objectives were classified as neither healthier nor less healthy for example sports supplements and baby food.

  • All fruit and vegetables were also discounted.

  • § 76 participants were lost to follow-up during the 0–6 month intervention phase (ie, no shopping data post-randomisation) and were therefore not included in final analyses. An additional 67 had no data during the 6–12 month follow-up period, and were not included in those analyses (distribution by social group available from authors on request). The remainder of this table is for all participants based on intention to treat.