Table 1. Baseline Characteristics of the Smart Cart Randomized Clinical Crossover Trial Participantsa.
| Characteristic | Participants with data available, No. | Participants, No. (%) | ||
|---|---|---|---|---|
| Overall (N = 209) | Group 1 (AB) (n = 104) | Group 2 (BA) (n = 105) | ||
| Age, mean (SD), yb | 209 | 55.4 (14.0) | 53.2 (13.9) | 57.5 (13.6) |
| Female | 207 | 187 (90.3) | 94 (91.3) | 93 (89.4) |
| Non-Hispanic White | 206 | 193 (94.1) | 96 (93.2) | 97 (94.2) |
| Bachelor’s degree or higher | 208 | 102 (49.0) | 50 (48.5) | 52 (49.5) |
| Annual household income ≥$100 000 | 161 | 81 (50.3) | 45 (52.3) | 36 (48.0) |
| Nonsmoking | 209 | 202 (96.7) | 98 (94.2) | 104 (99.1) |
| General health status | 208 | |||
| Excellent or very good | 154 (74.0) | 79 (76.0) | 75 (72.1) | |
| Good | 43 (21.0) | 18 (17.3) | 25 (24.0) | |
| Fair or poor | 11 (5.3) | 7 (6.7) | 4 (3.9) | |
| Body mass index, mean (SD)c | 198 | 25.5 (4.6) | 25.2 (4.8) | 25.7 (4.4) |
| Grocery Purchase Quality Index–16 score, mean (SD) | ||||
| Initial intervention period | 209 | 41.1 (7.1) | 41.2 (6.6) | 41.0 (7.5) |
| Crossover intervention period | 209 | 42.0 (7.3) | 41.0 (6.8) | 42.9 (7.7) |
| Spending on targeted foods, mean (SD), % | ||||
| Initial intervention period | 209 | 32.0 (10.6) | 32.0 (10.8) | 31.0 (10.5) |
| Crossover intervention period | 209 | 33.0 (12.6) | 32.0 (13.1) | 34.0 (12.1) |
| HEI-2020 score, mean (SD)d | ||||
| Baseline (n = 200) | 200 | 72.7 (9.1) | 73.0 (7.8) | 72.5 (10.3) |
| Midpoint (n = 170) | 170 | 71.5 (9.3) | 70.8 (8.5) | 72.3 (10.1) |
| Final (n = 170) | 170 | 73.2 (9.0) | 72.8 (7.9) | 73.7 (10.1) |
Abbreviation: HEI-2020, Healthy Eating Index–2010.
Group 1 received the treatment in period 1 followed by an active control in period 2 (AB design). Group 2 received the active control in period 1 followed by the intervention in period 2 (BA design).
After excluding participants whose spending was outside typical spending during the study period to create the analytic sample, age significantly differed at baseline between group 1 and group 2 (P = .02).
Body mass index is calculated as weight in kilograms divided by height in meters squared.
The HEI-2010 scores were a secondary outcome with a different analytic sample. Participants who reported eating less than 1000 kcal or more than 4500 kcal were deemed implausible30 and removed (24 participants at baseline, 23 participants at washout, and 28 participants at study completion, with 54 unique participants deleted because of implausible values and 170 participants left before multiple imputation). Because there were no missing data at baseline, 200 participants were included to calculate baseline HEI-2010 scores. Multiple imputation was performed on HEI-2010 scores of 170 participants.