Table 1

Comparison of responders and non-responders to the mental health online questionnaire containing childhood maltreatment in the UK Biobank

n=160 894
n=68 240
n=184 240
n=89 071
Continuous variables: mean (SD)
 Age (years)56.8 (8.4)56.6 (7.8)56.8 (8.1)55.5 (7.7)
 SBP (mmHg)141.3 (17.8)140.0 (16.8)136.3 (19.5)133.4 (18.4)
 DBP (mmHg)84.2 (10.1)83.8 (9.8)81.0 (10.1)80.1 (9.8)
 BMI (kg/m2)28.0 (4.3)27.3 (4.0)27.4 (5.3)26.4 (4.9)
Categorical variables: %
 Ethnicity (white)93.597.193.497.1
 Townsend deprivation index
  First quintile (20% least deprived)18.723.519.022.1
  Fifth quintile (20% most deprived)22.915.221.215.9
  None of the below22.
  College/university degree28.447.525.444.1
 Maternal smoking
  Do not know13.412.212.310.9
 Smoking status
  Never smoker34.435.545.243.9
  Former smoker51.455.944.549.9
  Current smoker14.38.610.36.2
 Alcohol intake
  Daily or almost daily24.028.614.619.1
  3–4 x/week24.928.718.823.9
  1–2 x/week26.624.225.925.4
  1–3 x/month9.18.513.112.9
  Special occasions only8.15.616.612.0
 Use of blood pressure medication26.620.520.212.6
 Use of cholesterol-lowering medication24.519.714.78.8
 Family history of CVD70.772.577.477.7
 Any CVD63.254.352.040.3
 Hypertensive disease51.943.440.129.4
 Ischaemic heart disease15.610.07.13.6
 Cerebrovascular disease5.
 Early onset12.610.09.47.1
  • All P-values for comparisons between non-responders and responders were <0.001, except for family history of CVD in women, which was 0.022.

  • *From the responders to the childhood maltreatment questionnaire, 98.4% of men and 97.1% of women responded to all questions on childhood maltreatment.

  • A-level, advanced level or equivalent; BMI, Body mass index; CSE, certificate of secondary education or equivalent; CVD, cardiovascular disease; DBP, diastolic blood pressure; HND, higher national diploma of equivalent; NVQ, national vocational qualification; O-level, ordinary level; SBP, systolic blood pressure.