Table 1.
Details of the non-imaging variables selected for our study.
| Variables | Raw Units |
Harmonised Units chosen | Value harmonised |
||||
|---|---|---|---|---|---|---|---|
| Whitehall | UK Biobank | Whitehall | UK Biobank | ||||
| Demographic | Age | Years (continuous) | Years (integer) | Years (integer) | 69.73 ± 5.15 | 61.46 ± 7.13 | ** |
| Sex | Categorical (binary) | Categorical (binary) | Categorical (binary) | M: 586 (82.19%) | M: 1013 (44.33%) | ** | |
| Biological | Weight | kg (continuous) | kg (continuous) | kg (continuous) | 78.72 ± 13.69 | 74.81 ± 14.68 | ** |
| Height | m (continuous) | cm (integer) | m (continuous) | 1.74 ± 0.08 | 1.70 ± 0.09 | ** | |
| BMI (Body Mass Index) | Kg/m2 (continuous) | Kg/m2 (continuous) | Kg/m2 (continuous) | 26.11 ± 4.09 | 26.05 ± 4.31 | ||
| Systolic blood pressure | mmHg (integer) | mmHg (integer) | mmHg (integer) | 141.31 ± 17.44 | 136.94 ± 19.03 | ** | |
| Diastolic blood Pressure | mmHg (integer) | mmHg (integer) | mmHg (integer) | 77.51 ± 10.71 | 78.10 ± 10.44 | ||
| Pulse | bpm (integer) | bpm (integer) | bpm (integer) | 67.57 ± 12.03 | 70.73 ± 12.09 | ** | |
| Hand class | Categorical (3 classes) | Categorical (4 classes) | Categorical (3 classes) | Right: 631 (88.50%), Left: 59 (8.27%), Ambidextrous: 23 (3.23%) | Right: 2034 (89.01%), Left: 211 (9.24%), Ambidextrous: 40 (1.75%) | ||
| Socioeconomic | Education | Years (int) | N/A | N/A | 19.10 ± 2.85 | N/A | |
| Health behaviours | Moderate physical activity | h/week (continuous) | day/week (integer), min/day (integer) | h/week (continuous) | 16.99 ± 27.59 | 4.27 ± 5.96 | ** |
| Vigorous physical activity | h/week (continuous) | min/day (integer) | h/week (continuous) | 9.41 ± 17.06 | 1.47 ± 2.27 | ** | |
| Combination of different motorial tasks | h/week (continuous) | day/week (integer), min/day (integer) | h/week (continuous) | 25.16 ± 34.87 | 5.32 ± 6.79 | ** | |
| Time spent watching TV | h/week (continuous) | h/day (integer) | h/week (integer) | 5.62 ± 3.28 | 19.07 ± 10.09 | ** | |
| Total walking activity | h/week (continuous) | min/day (integer) | h/week (continuous) | 10.10 ± 8.00 | 6.36 ± 6.68 | ** | |
| Sleep duration | h/day (continuous) | h/day (integer) | h/day (integer) | 6.92 ± 1.01 | 7.21 ± 0.96 | ** | |
| Smoker status | Categorical (binary) | Categorical (4 classes) | Categorical (binary) | Smoker: 27 (3.79%) | Smoker: 65 (2.84%) | ||
| Cigarette units | units/day (integer) | units/day (integer) | units/day (integer) | 0.45 ± 2.84 | 0.32 ± 2.20 | ||
| Alcohol status | Categorical (binary) | Categorical (4 classes) | Categorical (binary) | Consumer: 639 (89.62%) | Consumer: 2206 (96.54%) | ** | |
| Alcohol units | units/month (continuous) | units/day (categorical, 5 classes), day/week (categorical, 5 classes) | units/month (continuous) | 14.83 ± 15.16 | 5.26 ± 39.05 | ** | |
| CVD (cardiovascular disease) | Medications for Cardiovascular Disease | Categorical (binary) | Categorical (6 classes) | Categorical (binary) | Yes: 381 (53.44%) | Yes: 228 (9.98%) | ** |
| History of Cardiovascular Disease | Categorical (binary) | Categorical (6 classes) | Categorical (binary) | Yes: 133 (18.65%) | Yes: 442 (19.34%) | ||
| General health | Self-rated health | Categorical (4 classes) | Categorical (9 classes) | Categorical (4 classes) | Poor: 6 (0.84%), Fair: 52 (7.29%), Good: 224 (31.42%), Very good/Excellent: 431 (60.45%) | Poor: 17 (0.74%), Fair: 249 (10.90%), Good: 1425 (62.36%), Very good/Excellent: 594 (26.00%) | ** |
| Total number of medications | units (integer) | units (integer) | units (integer) | 2.84 ± 2.49 | 1.60 ± 1.81 | ** | |
| Medications for Blood Pressure | Categorical (binary) | Categorical (6 classes) | Categorical (binary) | Yes: 232 (32.54%) | Yes: 227 (9.93%) | ** | |
| History of Diabetes | Categorical (binary) | Categorical (4 classes) | Categorical (binary) | Yes: 62 (8.70%) | Yes: 68 (2.98%) | ** | |
| Mental health | Center for Epidemiologic Studies-Depression (CES-D) scale | Categorical (4 classes) | Categorical (5 classes) | Categorical (4 classes) | Not at all: 600 (84.15%), Several days: 90 (12.62%), More than half the days: 18 (2.53%), Nearly every day: 5 (0.70%) | Not at all: 1879 (82.23%), Several days: 362 (15.84%), More than half the days: 28 (1.23%), Nearly every day: 16 (0.70%) | * |
| Depression - Medications | Categorical (binary) | N/A | N/A | Yes: 29 (4.07%) | N/A | ||
| Cognitive skills | Trail Making Test (TMT) A | seconds (integer) | seconds (continuous) | seconds (integer) | 30.69 ± 11.10 | 37.72 ± 13.46 | ** |
| Trail Making Test (TMT) B | seconds (integer) | seconds (continuous) | seconds (integer) | 66.75 ± 33.72 | 62.15 ± 22.16 | ** | |
| Digit CODing (DCOD) | Correct answers (integer) | ~ | ~ | 63.13 ± 13.01 | ~ | ||
| Digit Span Backward (DSB) | u (integer) | u (integer) | u (integer) | 9.67 ± 2.44 | 7.07 ± 1.42 | ** | |
| Reaction time | ms (continuous) | ~ | ~ | 315.45 ± 68.03 | ~ | ||
For each variable we display the raw units (used at the time of data collection), the units chosen to harmonise the data, and the numerical values for the two cohorts in harmonised units, which allowed us to compare the two cohorts. The last column displays the results of the tests (t-test or chi-square, as appropriate) showing non-imaging differences between the two cohorts (* for p-values < 0.05 and ** for p-values < 0.01). Variables requiring the application of non-imaging harmonisation strategies are highlighted in bold. Legend: N/A = excluded due to lack of availability for all participants within the UK Biobank cohort, ~ = excluded due to substantial differences in the data collection across the two datasets.