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Table 3 Demographic characteristics of the NHSBT general donor population and of the INTERVAL cohort and trial

From: Recruitment and representativeness of blood donors in the INTERVAL randomised trial assessing varying inter-donation intervals

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 %)

  1. 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
  2. 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
  3. 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
  4. dIncluding donations where volume equals ’Normal’, ’Overweight’ or ’Missing’ (not including donations where volume equals ’Empty’ or ’Underweight’)
  5. 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
  6. 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
  7. 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
  8. SD, Standard deviation
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ISSN: 1745-6215