Table 1.
Baseline characteristics of SMARTER study participants by dietary data missingness status
| Characteristic | Total sample n 502 | Complete dietary data n 356 | Missing dietary data† n 146 | P-value | |||
|---|---|---|---|---|---|---|---|
| n/Median | %/p25, p75 | n/Median | %/p25, p75 | n/Median | %/p25, p75 | ||
| Demographic characteristics | |||||||
| Age, years | 45·5 | 32·0, 57·0 | 51·0 | 36·0, 60·0 | 35·0 | 29·0, 46·0 | < 0·0001* |
| Sex | |||||||
| Male | 103 | 20·5 | 75 | 21·1 | 28 | 19·2 | 0·63 |
| Female | 399 | 79·5 | 281 | 78·9 | 118 | 80·8 | |
| Race and ethnicity | |||||||
| Asian | 14 | 2·8 | 8 | 2·3 | 6 | 4·1 | 0·01* |
| Black | 48 | 9·6 | 32 | 9·0 | 16 | 11·0 | |
| Multiracial§ | 26 | 5·2 | 12 | 3·4 | 14 | 9·6 | |
| White | 414 | 82·5 | 304 | 85·4 | 110 | 75·3 | |
| Education, years | |||||||
| Mean | 16·4 | 16·5 | 16·4 | 0·72 | |||
| sd | 2·8 | 2·8 | 2·9 | ||||
| Employment | |||||||
| Full-time/part-time | 412 | 82·1 | 291 | 81·7 | 121 | 82·9 | 0·76 |
| Unemployed‡ | 90 | 17·9 | 65 | 18·3 | 25 | 17·1 | |
| Annual household income | |||||||
| < $60 000 | 143 | 28·5 | 97 | 30·0 | 46 | 34·6 | 0·34 |
| ≥ $60 000 | 313 | 62·4 | 226 | 70·0 | 87 | 65·4 | |
| Clinical characteristics (self-reported) | |||||||
| High blood pressure | 106 | 21·1 | 87 | 24·4 | 19 | 13·0 | < 0·01* |
| High cholesterol | 88 | 17·5 | 74 | 20·8 | 14 | 9·6 | < 0·01* |
| High TAG | 56 | 11·2 | 44 | 12·4 | 12 | 8·2 | 0·18 |
| Smoking status | |||||||
| Never smoker | 385 | 76·7 | 273 | 76·7 | 112 | 76·7 | 0·48 |
| Current smoker | 14 | 2·8 | 8 | 2·3 | 6 | 4·1 | |
| Former smoker | 103 | 20·5 | 75 | 21·1 | 28 | 19·2 | |
| Anthropometric measures | |||||||
| BMI, kg/m2 | 33·3 | 30·7, 36·6 | 33·1 | 30·3, 36·2 | 33·8 | 31·0, 37·5 | 0·03* |
| Mean | sd | Mean | sd | Mean | sd | ||
| Average waist circumference, cm | |||||||
| Men | 113·1 | 12·2 | 112·5 | 11·9 | 114·7 | 13·0 | 0·43 |
| Women | 105·3 | 11·1 | 105·5 | 10·5 | 104·9 | 12·4 | 0·62 |
| Average systolic blood pressure, mmHg | 118·2 | 15·4 | 119·1 | 15·1 | 116·0 | 16·0 | 0·04* |
| Average diastolic blood pressure, mmHg | 77·0 | 10·8 | 76·9 | 10·8 | 77·0 | 10·9 | 0·97 |
Notes: BMI, Body mass index; TAG, triglycerdies. For categorical variables, P-values were obtained using the chi-square test of independence. For age, BMI and body fat percentage the Wilcoxon rank-sum test were used to assess differences by missingness category because of non-normality identified during visualisation of histograms and q–q plots. Two-sided P-values are presented. For all other continuous variables, two sample t tests were used to assess differences by missingness category as plots suggested normality. For all continuous variables except female waist circumference, the pooled variance method was used as variances were equal. Separate-variance t tests with the Satterthwaite method approximation of degrees of freedom were used for female waist circumference.
Statistically significant at the P < 0·05 level.
†Dietary data were missing at 6 and/or 12 months if there were 0 recalls collected at that timepoint.
‡The Unemployed category includes participants who were unemployed, retired or disabled.
§Indicates participants who self-reported ‘yes’ to a question, ‘Are you of more than one racial/ethnic background?’.