Table 2

Distribution of exposure and confounder variables by AMD status

VariablesOutcome statusP value*
No AMD (n=129 705)AMD (n=3634)
Age groups (% (n))<0.001
 50–5418.26 (23 684)8.45 (307)
 55–5922.03 (28 580)14.97 (544)
 60–6432.3 (41 890)32.33 (1175)
 65–7027.41 (35 551)44.25 (1608)
Female gender (% (n))54.51 (70 704)60.59 (2202)<0.001
Ethnicity (% (n))=0.004
 White93.38 (120 600)94.22 (3408)
 Black2.11 (2731)1.52 (55)
 East Asian0.36 (462)0.55 (20)
 South Asian2.51 (3240)1.85 (67)
 Any mixed0.56 (729)0.69 (25)
 Other1.07 (1387)1.16 (42)
Visual impairment (% (n))<0.001
 Visual impairment (≥0.3)3.62 (3138)8.67 (103)
BMI (mean(CI))27.63 (27.60–27.65)27.75 (27.59–27.92)=0.118
Smoking status (% (n))=0.013
 Never53.19 (68 730)51.42 (1861)
 Previous37.64 (48 639)40.01 (1448)
 Current9.16 (11 842)8.57 (310)
Systolic BP (mean(CI))140.29 (140.18–140.39)141.74 (141.12–142.35)<0.001
Diastolic BP (mean(CI))82.31 (82.26–82.37)81.89 (81.53–82.19)=0.007
Diabetes (%(n))7.6 (9,825)9.11(330)=0.001
Vascular/Heart disease (% (n))36.24 (46 919)42.74 (1550)<0.001
Waist/Hip ratio (mean (CI))0.88 (0.88–0.88)0.88 (0.87–0.88)=0.002
Pulse rate (mean (CI))69.02 (68.95–69.08)69.86 (69.48–70.24)<0.001
Qualifications (% (n))=0.06
 None of the above19.64(25 127)21.00 (750)
 Lower academic/vocational31.45 (40 230)29.99 (1071)
 Higher academic/professional48.91 (62 566)49.01 (1750)
Employment (% (n))<0.001
 None of the above0.63 (817)0.52 (19)
 In paid employment45.39 (58 642)31.1 (1126)
 Retired45.68 (59 013)61.2 (2216)
 Looking after home and/or family2.15 (2781)1.27 (46)
 Unable to work because of sickness or disability3.75 (4846)4.45 (161)
 Unemployed1.75 (2256)0.91 (33)
 Doing unpaid or voluntary work0.52 (671)0.47 (17)
 Full or part-time student0.13 (165)0.08 (3)
Household income (% (n))<0.001
 Less than 18 00026.7 (29 085)33.64 (1011)
 18 000 to 30 99927.6 (29 085)29.18 (877)
 31 000 to 51 99923.86 (25 988)22.4 (673)
 52 000 to 100 00017.13 (18 656)11.71 (352)
 Greater than 100 0004.7 (5124)3.06(92)
Townsend Deprivation Index (mean (CI))−1.17 (−1.19 to −1.15)−1.30 (−1.40 to −1.20)<0.001
  • *P value from Wilcoxon rank-sum test for continuous variables and Ψ2 test for categorical variables. All totals may not add up to 133 339 due to missing data.

  • AMD, age-related macular degeneration; BMI, body mass index; BP, blood pressure.