Table 1 Study participant characteristics at study entry for those with/without eczema or psoriasis, data are n (%) for categorical variables and median (IQR) for continuous variables

Follow-up time (years)

4.5 (1.7–9.1)

4.9 (1.9–9.5)

4.4 (1.7–8.9)

4.7 (1.8–9.3)

5.7 (2.3–11.0)

5.4 (2.1–10.9)

5.6 (2.2–10.9)

5.3 (2.1–10.6)

Sex (female)

2,023,172 (54%)

484,720 (56%)

1,665,708 (52%)

431,807 (54%)

659,460 (48%)

155,059 (50%)

535,278 (45%)

136,554 (48%)

Age

38.6 (23.8–59.6)

39.9 (24.1–60.8)

37.3 (22.8–59.6)

39.3 (23.4–61.0)

43.4 (30.2–59.7)

44.0 (30.7–60.1)

43.0 (29.6–60.0)

43.8 (30.4–60.3)

 18–39

1,936,683 (52%)

432,946 (50%)

1,729,474 (54%)

404,386 (51%)

603,064 (44%)

133,399 (43%)

529,725 (45%)

123,152 (44%)

 40–49

456,639 (12%)

107,595 (12%)

365,872 (11%)

93,802 (12%)

223,800 (16%)

51,711 (17%)

184,885 (16%)

45,724 (16%)

 50–59

416,104 (11%)

99,094 (11%)

338,787 (10%)

87,368 (11%)

201,742 (15%)

47,179 (15%)

168,318 (14%)

42,214 (15%)

 60–69

403,886 (11%)

96,209 (11%)

348,075 (11%)

88,132 (11%)

168,935 (12%)

39,295 (13%)

146,033 (12%)

35,972 (13%)

 70–79

317,043 (8.5%)

78,907 (9.1%)

283,161 (8.8%)

74,106 (9.3%)

114,154 (8.4%)

26,201 (8.4%)

101,858 (8.7%)

24,465 (8.6%)

 80 + 

190,123 (5.1%)

49,235 (5.7%)

163,515 (5.1%)

45,502 (5.7%)

53,563 (3.9%)

12,296 (4.0%)

46,480 (3.9%)

11,339 (4.0%)

Carstairs deprivation quintile

 1 (least deprived)

693,976 (19%)

164,020 (20%)

609,450 (20%)

153,083 (20%)

239,381 (18%)

54,491 (18%)

209,265 (19%)

50,577 (19%)

 2

726,785 (20%)

169,436 (20%)

634,456 (20%)

156,814 (20%)

258,876 (20%)

58,095 (20%)

224,322 (20%)

53,369 (20%)

 3

763,684 (21%)

177,947 (21%)

663,782 (21%)

163,294 (21%)

285,488 (22%)

64,962 (22%)

248,284 (22%)

59,633 (22%)

 4

804,513 (22%)

185,506 (22%)

684,904 (22%)

167,523 (22%)

301,611 (23%)

68,634 (23%)

255,341 (23%)

61,631 (23%)

 5 (most deprived)

616,149 (17%)

139,516 (17%)

529,446 (17%)

126,108 (16%)

222,091 (17%)

50,356 (17%)

187,961 (17%)

44,999 (17%)

 Unknown

115,371

27,561

106,846

26,474

57,811

13,543

52,126

12,657

Asthma diagnosis

418,760 (11%)

194,298 (22%)

355,302 (11%)

175,497 (22%)

-

-

-

-

Psoriatic arthritis

-

-

-

-

8572 (0.6%)

3638 (1.2%)

6841 (0.6%)

3114 (1.1%)

Charlson’s comorbidity index

 Low

2,777,741 (75%)

542,649 (63%)

2,434,982 (75%)

503,973 (64%)

1,010,496 (74%)

219,105 (71%)

881,218 (75%)

202,700 (72%)

 Moderate

803,045 (22%)

284,506 (33%)

681,188 (21%)

257,585 (32%)

305,143 (22%)

77,690 (25%)

256,072 (22%)

68,853 (24%)

 Severe

139,692 (3.8%)

36,831 (4.3%)

112,714 (3.5%)

31,738 (4.0%)

49,619 (3.6%)

13,286 (4.3%)

40,009 (3.4%)

11,313 (4.0%)

BMI

25.2 (22.3–28.7)

25.4 (22.5–29.0)

25.1 (22.2–28.6)

25.2 (22.4–28.8)

25.6 (22.7–29.1)

26.1 (23.1–29.8)

25.5 (22.7–28.9)

26.0 (23.1–29.7)

 Unknown

893,396

149,905

826,059

144,397

272,289

45,254

248,099

42,476

Obesity (categorised)

 No evidence of obesity

3,173,900 (85%)

717,101 (83%)

2,788,149 (86%)

667,059 (84%)

1,141,895 (84%)

245,756 (79%)

996,546 (85%)

226,971 (80%)

 Obese class I (30–34.9)

366,497 (9.9%)

96,216 (11%)

301,783 (9.3%)

84,553 (11%)

151,030 (11%)

41,773 (13%)

125,007 (11%)

37,148 (13%)

 Obese class II (35–39.9)

121,446 (3.3%)

33,420 (3.9%)

95,213 (2.9%)

28,048 (3.5%)

49,001 (3.6%)

14,862 (4.8%)

38,407 (3.3%)

12,628 (4.5%)

 Obese class III (40 +)

58,635 (1.6%)

17,249 (2.0%)

43,739 (1.4%)

13,636 (1.7%)

23,332 (1.7%)

7690 (2.5%)

17,339 (1.5%)

6119 (2.2%)

Harmful alcohol use

96,328 (2.6%)

28,327 (3.3%)

72,753 (2.3%)

22,983 (2.9%)

41,845 (3.1%)

13,901 (4.5%)

31,626 (2.7%)

11,147 (3.9%)

Smoking status

 Non-smoker

1,858,380 (57%)

456,720 (56%)

1,642,116 (58%)

431,014 (58%)

662,851 (54%)

131,125 (45%)

580,837 (55%)

123,149 (46%)

 Current smoker

642,990 (20%)

157,434 (19%)

523,575 (19%)

134,145 (18%)

255,508 (21%)

77,270 (26%)

210,144 (20%)

66,833 (25%)

 Ex-smoker

687,105 (21%)

181,117 (22%)

575,059 (20%)

163,142 (22%)

273,966 (22%)

74,257 (25%)

229,228 (22%)

67,047 (25%)

 Current or ex-smoker

97,395 (3.0%)

20,466 (2.5%)

76,982 (2.7%)

16,700 (2.2%)

36,229 (2.9%)

9614 (3.3%)

28,182 (2.7%)

7951 (3.0%)

 Unknown

434,608

48,249

411,152

48,295

136,704

17,815

128,908

17,886

Sleep problems

257,752 (6.9%)

109,378 (13%)

190,349 (5.9%)

88,728 (11%)

-

-

-

-

Severe eczema

 None

3,720,478 (100%)

-

3,228,884 (100%)

-

1,365,258 (100%)

-

1,177,299 (100%)

-

 Mild

-

638,977 (74%)

-

587,271 (74%)

-

303,327 (98%)

-

277,113 (98%)

 Moderate

-

208,757 (24%)

-

190,798 (24%)

 Severe

-

16,252 (1.9%)

-

15,227 (1.9%)

-

6754 (2.2%)

-

5753 (2.0%)