Table 3.
Demographic characteristics of the NHSBT general donor population and of the INTERVAL cohort and trial
| Demographics | INTERVAL cohort | |||
|---|---|---|---|---|
| n (%) or mean (SD) | INTERVAL cohort | NHSBT general donor population | Randomised in INTERVAL trial | Not randomised |
| All donors | 48,692 (100.0 %)a | 1,330,506 (100.0 %) | 45,235 (100.0 %)a | 3457 (100.0 %) |
| Sex | ||||
| Male | 24,212 (49.7 %) | 586,372 (44.1 %) | 22,456 (49.6 %) | 1756 (50.8 %) |
| Female | 24,480 (50.3 %) | 744,134 (55.9 %) | 22,779 (50.4 %) | 1701 (49.2 %) |
| Age at baseline (years) | 43.1 (14.3) | 42.3 (15.0) | 43.3 (14.2) | 39.9 (14.7) |
| Age at baseline | ||||
| 17–24 | 6424 (13.2 %) | 234,367 (17.6 %) | 5679 (12.6 %) | 745 (21.6 %) |
| 25–34 | 10,236 (21.0 %) | 235,238 (17.7 %) | 9468 (20.9 %) | 768 (22.2 %) |
| 35–44 | 9095 (18.7 %) | 246,225 (18.5 %) | 8500 (18.8 %) | 595 (17.2 %) |
| 45–-54 | 11,158 (22.9 %) | 304,927 (22.9 %) | 10,456 (23.1 %) | 702 (20.3 %) |
| 55–-64 | 8822 (18.1 %) | 221,143 (16.6 %) | 8362 (18.5 %) | 460 (13.3 %) |
| 65+ | 2957 (6.1 %) | 88,606 (6.7 %) | 2770 (6.1 %) | 187 (5.4 %) |
| Ethnicity | ||||
| White | 44,192 (90.8 %) | 1,207,593 (90.8 %) | 41,259 (91.2 %) | 2933 (84.8 %) |
| Asian | 1127 (2.3 %) | 31,829 (2.4 %) | 941 (2.1 %) | 186 (5.4 %) |
| Black African | 118 (0.2 %) | 3852 (0.3 %) | 105 (0.2 %) | 13 (0.4 %) |
| Black Caribbean | 307 (0.6 %) | 4971 (0.4 %) | 271 (0.6 %) | 36 (1.0 %) |
| Black other | 31 (0.1 %) | 743 (0.1 %) | 29 (0.1 %) | 2 (0.1 %) |
| Chinese | 164 (0.3 %) | 3831 (0.3 %) | 141 (0.3 %) | 23 (0.7 %) |
| Mixed | 679 (1.4 %) | 14,838 (1.1 %) | 606 (1.3 %) | 73 (2.1 %) |
| Other | 138 (0.3 %) | 3558 (0.3 %) | 122 (0.3 %) | 16 (0.5 %) |
| Unknown | 1936 (4.0 %) | 59,291 (4.5 %) | 1761 (3.9 %) | 175 (5.1 %) |
| Blood group | ||||
| A RhD positive (A+) | 14,737 (30.3 %) | 397,277 (29.9 %) | 13,768 (30.4 %) | 969 (28.0 %) |
| A RhD negative (A-) | 3744 (7.7 %) | 97,450 (7.3 %) | 3489 (7.7 %) | 255 (7.4 %) |
| B RhD positive (B+) | 4244 (8.7 %) | 102,650 (7.7 %) | 3877 (8.6 %) | 367 (10.6 %) |
| B RhD negative (B-) | 1070 (2.2 %) | 27,317 (2.1 %) | 993 (2.2 %) | 77 (2.2 %) |
| O RhD positive (O+) | 17,642 (36.2 %) | 460,501 (34.6 %) | 16,398 (36.3 %) | 1244 (36.0 %) |
| O RhD negative (O-) | 5542 (11.4 %) | 138,349 (10.4 %) | 5138 (11.4 %) | 404 (11.7 %) |
| AB RhD positive (AB+) | 1293 (2.7 %) | 33,817 (2.5 %) | 1199 (2.7 %) | 94 (2.7 %) |
| AB RhD negative (AB-) | 402 (0.8 %) | 9550 (0.7 %) | 368 (0.8 %) | 34 (1.0 %) |
| Unknown | 18 (0.0 %) | 63,595 (4.8 %) | 5 (0.0 %) | 13 (0.4 %) |
| Distance to nearest static donor centre (miles)b | ||||
| 0–4 | 30,405 (62.4 %) | 252,068 (18.9 %) | 27,971 (61.8 %) | 2434 (70.4 %) |
| 5–9 | 9801 (20.1 %) | 245,652 (18.5 %) | 9236 (20.4 %) | 565 (16.3 %) |
| 10–29 | 7203 (14.8 %) | 584,850 (44.0 %) | 6832 (15.1 %) | 371 (10.7 %) |
| 30–59 | 775 (1.6 %) | 220,388 (16.6 %) | 730 (1.6 %) | 45 (1.3 %) |
| 60+ | 98 (0.2 %) | 18,045 (1.4 %) | 93 (0.2 %) | 5 (0.1 %) |
| Unknown | 410 (0.8 %) | 9503 (0.7 %) | 373 (0.8 %) | 37 (1.1 %) |
| Donor status at baselinec | ||||
| New | 1392 (2.9 %) | 288,653 (21.7 %) | 1147 (2.5 %) | 245 (7.1 %) |
| Occasional | 7912 (16.2 %) | 226,507 (17.0 %) | 7053 (15.6 %) | 859 (24.8 %) |
| More frequent | 39,388 (80.9 %) | 815,346 (61.3 %) | 37,035 (81.9 %) | 2353 (68.1 %) |
| Donations (over last 2 years prior to baseline)d | ||||
| All donations | 3.28 (2.00) | 2.24 (2.37) | 3.33 (2.00) | 2.61 (1.92) |
| Whole-blood donations | 3.19 (1.81) | 2.08 (1.87) | 3.23 (1.80) | 2.55 (1.80) |
| Other donations | 0.10 (1.05) | 0.16 (1.64) | 0.10 (1.07) | 0.06 (0.79) |
| Deferrals (during the 2 years prior to baseline)e | ||||
| Deferral for low haemoglobin | 3308 (6.8 %) | 63,071 (4.7 %) | 3094 (6.8 %) | 214 (6.2 %) |
| Any other deferral | 14,628 (30.0 %) | 327,747 (24.6 %) | 13,632 (30.1 %) | 996 (28.8 %) |
| Length of NHSBT donation history at baseline (years)f | 10.7 (8.4) | 8.58 (8.44) | 10.9 (8.4) | 8.47 (8.02) |
| Venue type attended at baselineg | ||||
| Static centre | 48,692 (100.0 %) | 99,724 (7.5 %) | 45,235 (100.0 %) | 3457 (100.0 %) |
| Mobile | 0 (0.0 %) | 1,230,782 (92.5 %) | 0 (0.0 %) | 0 (0.0 %) |
aThe characteristics of 33 donors in the INTERVAL cohort (of whom 28 are in the INTERVAL trial) could not be identified in the PULSE database due to merged donor records
bThe correspondence address (used to calculate ’Distance to nearest static donor centre’ and derive ’Region’) was correct at the time the data were extracted from PULSE (Nov 2015). Historical correspondence addresses were not available in PULSE
c ’New’ has been defined according to the classification used by NHSBT, i.e. an individual who has not previously provided a full donation is considered to be a new donor. ’Occasional’ and ’More frequent’ have been defined as less than or equal to two full donations in the last 5 years and more than two full donations in the last 5 years, respectively
dIncluding donations where volume equals ’Normal’, ’Overweight’ or ’Missing’ (not including donations where volume equals ’Empty’ or ’Underweight’)
eDeferrals during the 2 years prior to baseline were summarised as counts of people with a deferral for low haemoglobin levels and more generally deferral for reasons other than low haemoglobin
fLength of donation history with NHSBT at baseline was defined as the period of time between baseline and the minimum of date of registration, date of first attendance (whether successful or not) and date of first successful donation
gFor venue type, some old venues that are no longer used do not have an associated PULSE venue code. In these cases, although venue type was missing, because the only venues that were no longer being used were mobile venues, we have assumed that the venue type was mobile
SD, Standard deviation