Table 2:

Characteristics of participants at baseline during the 2003/04 and 2009/10 cohort years

Characteristic	No. (%)^*

	Influenza vaccine 2003/04			Influenza vaccine 2009/10

	Yes	No	p	Yes	No	p
Participants	44 604 (66.5)	22 463 (33.5)	–	69 594 (65.0)	37 419 (35.0)	–

Age, yr, mean ± SD	66.2 ± 13.3	56.2 ± 16.3	< 0.001^†	65.8 ± 13.8	58.4 ± 17.2	< 0.001^†

Age group, yr

< 65	17 309 (38.8)	15 517 (69.1)	< 0.001^‡	29 463 (42.3)	22 875 (61.1)	< 0.001^‡

65–70	8 676 (19.5)	2 319 (10.3)		11 470 (16.5)	4 491 (12.0)

71–80	14 006 (31.4)	3 229 (14.4)		20 612 (29.6)	6 581 (17.6)

≥81	4 613 (10.3)	1 398 (6.2)		8 049 (11.6)	3 472 (9.3)

Male sex	24 038 (53.9)	12 179 (54.2)		38 190 (54.9)	18 971 (50.7)

Smoking status			< 0.001^‡			< 0.001^‡

Current smoker	5 454 (12.2)	4 442 (19.8)	< 0.001^‡	8 455 (12.2)	7 087 (18.9)	< 0.001^‡

Nonsmoker	20 774 (46.6)	10 074 (44.8)		33 533 (48.2)	17 679 (47.2)

Former smoker	16 915 (37.9)	5 996 (26.7)		27 515 (39.5)	10 937 (29.2)

Missing data	1 461 (3.3)	1 951 (8.7)		91 (0.1)	1 716 (4.6)

BMI, mean ± SD	29.5 ± 6.0	30.1 ± 6.5	< 0.001^†	30.5 ± 6.4	30.5 ± 6.9	0.137^†

Cholesterol, mmol/L, mean ± SD	4.7 ± 1.0	5.0 ± 1.1	< 0.001^†	4.3 ± 1.0	4.6 ± 1.1	< 0.001^†

SBP, mm Hg, mean ± SD	141.0 ± 15.9	138.9 ± 17.9	< 0.001^†	135.5 ± 14.2	134.9 ± 16.6	< 0.001^†

DBP, mm Hg, mean ± SD	77.9 ± 8.5	80.4 ± 9.8	< 0.001^†	75.9 ± 8.6	78.2 ± 9.7	< 0.001^†

HbA_1c, %, mean ± SD	7.5 ± 1.41	7.9 ± 1.80	< 0.001^†	7.3 ± 1.4	7.7 ± 1.80	< 0.001^†

No. of comorbid conditions, median (IQR)	(0–2)	(0–1)	< 0.001^§	1 (0–2)	(0–1)	< 0.001^§

Recorded clinical history

Heart failure	4 503 (10.1)	990 (4.4)	< 0.001^‡	4 578 (6.6)	1 616 (4.3)	< 0.001^‡

Stroke	1 857 (4.2)	1 504 (6.7)	< 0.001^‡	6 525 (9.4)	2 604 (6.9)	< 0.001^‡

Myocardial infarction	3 731 (8.4)	1 313 (5.8)	< 0.001^‡	3028 (8.7)	2121 (5.7)	< 0.001^‡

COPD	4 750 (10.6)	410 (1.8)	< 0.001^‡	4631 (6.6)	1203 (3.2)	< 0.001^‡

Asthma	5 900 (13.2)	2 377 (10.6)	< 0.001^‡	10 348 (14.9)	4 738 (12.7)	< 0.001^‡

Cancer	2 524 (5.7)	773 (3.4)	< 0.001^‡	4 844 (7.0)	1 627 (4.3)	< 0.001^‡

Atrial fibrillation	3 280 (7.3)	785 (3.5)	< 0.001^‡	5 439 (7.8)	1 730 (4.6)	< 0.001^‡

Chronic kidney disease	2 276 (5.1)	625 (2.8)	< 0.001^‡	19 164 (27.5)	5 811 (15.5)	< 0.001^‡

Medication

Oral antihyperglycaemic drug	28 007 (62.8)	10 438 (46.5)	< 0.001^‡	49 302 (70.8)	25 305 (67.6)	< 0.001^‡

Insulin	9 782 (21.9)	4 589 (20.4)	< 0.001^‡	14 911 (21.4)	8 555 (22.9)	< 0.001^‡

Antihypertensive agent

ACE or ARB	24 476 (54.9)	7 779 (34.6)	< 0.001^‡	49 092 (70.5)	19 826 (53.0)	< 0.001^‡

β-blocker	16 215 (36.4)	5 547 (24.7)	< 0.001^‡	28 999 (71.8)	11 402 (30.5)	< 0.001^‡

Other	27 897 (62.5)	8 880 (39.5)	< 0.001^‡	46 316 (66.5)	18 350 (49.0)	< 0.001^‡

Lipid-lowering agent	22 301 (50.0)	7 083 (31.5)	< 0.001^‡	57 228 (82.2)	23 406 (62.5)	< 0.001^‡

Anticoagulant/antiplatelet drug	22 315 (50.0)	6 458 (28.7)	< 0.001^‡	43 354 (62.3)	16 875 (45.1)	< 0.001^‡

Immunosuppressant	687 (1.5)	224 (1.0)	< 0.001^‡	1 517 (2.2)	499 (1.3)	< 0.001^‡

No. of medications, median (IQR)	4 (2–6)	2 (1–4)	< 0.001^§	5 (3–7)	4 (2–6)	< 0.001^§

Hospital admissions during past year, no. (%)	11 552 (25.8)	4 726 (21.0)	< 0.001^‡	19 531 (28.1)	9 579 (25.6)	< 0.001^‡

Pneumococcal vaccine during past 5 yr, no. (%)	15 995 (35.9)	2 638 (11.7)	< 0.001^‡	28 904 (41.5)	7 627 (20.4)	< 0.001^‡

Influenza vaccine during past year, no. (%)	35 940 (80.6)	3 473 (15.5)	< 0.001^‡	60 016 (86.2)	7 110 (19.0)	< 0.001^‡

Note: ACE = angiotensin-converting enzyme, ARB = angiotensin-receptor blocker, BMI = body mass index, COPD = chronic obstructive pulmonary disease, DBP = diastolic blood pressure, HbA_1c = glycated hemoglobin, IQR = interquartile range, SBP = systolic blood pressure, SD = standard deviation.
↵* Unless otherwise specified.
↵† Student t test.
↵‡ χ² test.
↵§ Mann–Whitney test.