Table 4

Association between serum 25-hydroxyvitamin D and change in hip pain over 2.4 years, as assessed by the WOMAC questionnaire

UnivariateMultivariate model 1Multivariate model 2
β coefficient
(95% CI)
(n=765)
p Valueβ coefficient
(95% CI)
(n=765)
p Valueβ coefficient
(95% CI)
(n=602)
p Value
Vitamin D (continuous measure)
 Change in total hip WOMAC score−0.002 (−0.02 to 0.02)0.830.0003 (−0.02 to 0.02)0.970.01 (−0.01 to 0.04)0.27
 Change in hip pain when….
  Walking on a flat surface−0.001 (−0.006 to 0.004)0.70−0.001 (−0.006 to 0.004)0.820.002 (−0.004 to 0.007)0.58
  Going up and down stairs−0.001 (−0.006 to 0.004)0.610.0006 (−0.004 to 0.006)0.810.003 (−0.003 to 0.008)0.31
  At night while in bed0.0001 (−0.005 to 0.005)0.980.0002 (−0.005 to 0.006)0.950.003 (−0.003 to 0.009)0.33
  Sitting or lying0.001 (−0.004 to 0.005)0.800.001 (−0.004 to 0.005)0.700.004 (−0.001 to 0.009)0.11
  Standing upright−0.001 (−0.005 to 0.004)0.80−0.001 (−0.005 to 0.004)0.760.002 (−0.003 to 0.007)0.42
Vitamin D (<25 nmol/l compared with ≥25 nmol/l)
 Change in total hip WOMAC score2.19 (−0.26 to 4.64)0.082.20 (−0.29 to 4.69)0.0832.31 (−0.69 to 5.3)0.13
 Change in hip pain when….
  Walking on a flat surface0.42 (−0.26 to 1.10)0.220.42 (−0.27 to 1.11)0.230.54 (−0.29 to 1.38)0.20
  Going up and down stairs0.52 (−0.05 to 1.09)0.070.48 (−0.09 to 1.05)0.090.52 (−0.17 to 1.21)0.14
  At night while in bed0.48 (−0.13 to 1.09)0.120.50 (−0.12 to 1.12)0.120.52 (−0.14 to 1.19)0.12
  Sitting or lying0.30 (−0.03 to 0.63)0.070.31 (−0.05 to 0.66)0.090.17 (−0.23 to 0.57)0.40
  Standing upright0.47 (−0.16 to 1.10)0.140.49 (−0.13 to 1.11)0.120.47 (–0.30 to 1.25)0.23
  • Model 1: Adjusted for age, sex BMI and season (summer, autumn / winter, spring).

  • Model 2: Further adjusted for leg strength, radiographic hip osteoarthritis (present/absent), use of pain medication at baseline, and baseline WOMAC score (same scale—for example, baseline total hip WOMAC score for change in total hip WOMAC score).

  • Change in WOMAC score is from phase 2 to phase 3 (2.4 years).

  • BMI, body mass index; WOMAC, Western Ontario and McMaster University Osteoarthritis Index.