Table 1

Characteristics of the UK Twins Spine study sample by LBP status

LBP1 absentLBP1 present
Predictor variableXSDNXSDNANOVA (F), p value
Age (year)49.9511.78171051.4810.285467.34, 0.007*
Height (m)1.620.0617101.630.0654612.00, 0.0004*
Weight (kg)64.8911.32170968.9712.9354449.97, 0.0001*
BMI (kg/m2)24.694.29170925.924.7954433.21, 0.0001*
Smoking (packs/year)4.109.6810504.1910.273020.7, 0.413
Manual work2.196.4617102.976.925465.80, 0.016
PhysExers (yes)60.73%75380.76%361χ2=58.8, <0.0001
LHT3.452.566544.932.8318245.40, 0.001*
LSIG5.703.286567.072.9918325.96, 0.001*
LBUL2.001.746562.861.8418333.87, 0.001*
LOST1.351.856541.992.4218314.98, 0.001*
LSUM12.527.3065216.827.9218247.67, 0.001*
LBP1_Q0.7141.88717305.0832.6225221256.02, 0.0001
  • LBP_1 represents low back pain (LBP) defined as pain associated with disability lasting more than a month over life time (other LBP phenotypes defined in the Patients and methods section).

  • * The analysis of variance (ANOVA) result was confirmed by Kruskal–Wallis test.

  • Kruskal–Wallis test (χ2 and p value), mean group ranks are provided in parentheses.

  • Percentage who exercised.

  • § Percentage who complained.

  • LBP1-absent individuals can have LBP1_Q>0, if the length of time they have had back pain is less than 1 month throughout their whole life. For an individual to be LBP1-present, they need to have disabling pain lasting longer than 1 month.

  • BMI, body mass index; LBUL, disc bulge; LHT, disc height; LOST, anterior osteophytes; LSIG, disc signal intensity; LSUM, summary rank for four lumbar disc degeneration traits; N, sample size; X, mean or proportion.