Table 1. Distribution of participants in the UKBB across the different variables.
Mean/sd or percentage of the 83,751 study participants in the UKBB by sex. P values estimated by a t-test for continuous variables and chi-squared test for categorical variables in order to determine whether there is a systematic difference between males and females.
| variable | total | males | females | P value |
|---|---|---|---|---|
| Age, years | 57.1 (8.1) | 57.3 (8.2) | 56.9 (8.0) | < .001 |
| Ethnicity white | 92.1 | 92.2 | 92 | < .001 |
| Ethnicity asian | 3.5 | 4 | 3.1 | |
| Ethnicity black | 3.1 | 2.8 | 3.3 | |
| Ethnicity mixed | 0.9 | 0.7 | 1 | |
| Ethnicity chinese | 0.4 | 0.3 | 0.5 | |
| Age completed full time education | 16.9 (2.5) | 16.9 (2.7) | 16.8 (2.3) | < .001 |
| Skin colour * | 2.3 (0.9) | 2.4 (0.9) | 2.3 (0.9) | < .001 |
| Use of UV protection | 2.7 (0.9) | 2.5 (0.9) | 2.9 (0.9) | < .001 |
| Alcohol intake ** | 3.0 (1.6) | 3.3 (1.5) | 2.8 (1.6) | < .001 |
| Season of assessment spring | 34.6 | 34.7 | 34.6 | |
| Season of assessment autumn | 23.7 | 23.5 | 23.8 | |
| Season of assessment winter | 22.1 | 22.4 | 21.9 | |
| Season of assessment summer | 19.6 | 19.5 | 19.7 | |
| Corneal-compensated IOP, mmHg | 16.1 (4.2) | 16.4 (4.2) | 15.9 (4.3) | < .001 |
| Corneal resistance factor | 10.7 (2.3) | 10.6 (2.3) | 10.9 (2.4) | < .001 |
| Corneal hysteresis | 10.6 (2.3) | 10.4 (2.2) | 10.8 (2.3) | < .001 |
| Height, m | 168.3 (9.2) | 175.7 (6.8) | 162.7 (6.3) | < .001 |
| Weight, 10 kg | 77.4 (15.8) | 85.5 (14.2) | 71.3 (14.0) | < .001 |
| BMI, kg/m2 | 27.3 (4.8) | 27.7 (4.2) | 27.0 (5.1) | < .001 |
| SBP, mmHg | 139.7 (19.5) | 142.3 (18.3) | 137.6 (20.2) | < .001 |
| DBP, mmHg | 81.9 (10.6) | 83.6 (10.4) | 80.5 (10.5) | < .001 |
| Townsend deprivation index | -1.0 (3.0) | -1.0 (3.0) | -1.0 (2.9) | |
| Smoker: true | 90.1 | 87.9 | 91.8 | < .001 |
| Smoker: false | 9.9 | 12.1 | 8.2 | |
| Age Asthma Diagnosed, self-reported | 30.5 (18.5) | 27.3 (19.1) | 32.7 (17.7) | < .001 |
| Diabetes, doctor diagnosed: true | 94.8 | 93.1 | 96.1 | < .001 |
| Diabetes, doctor diagnosed: false | 5.2 | 6.9 | 3.9 |
* Skin colour is coded as: very fair = 1, fair = 2, light olive = 3, dark olive = 4, brown = 5, black = 6
** Alcohol intake is coded as: never = 0, special occasions = 1, one to three times a month = 2, once twice a week = 3, three four times a week = 4, daily = 5.