Table 3

Stepwise multivariate analysis assessing the variance of serum 25-OHD levels in COPD

Explanatory variablesParameter estimate (β) (95% CI)P value
Intercept15 (9.8 to 21)<0.0001
FEV1, % predicted0.087 (0.05 to 0.12)<0.0001
Seasonal variation1.9 (0.79 to 3.0)0.0009
rs7041 variant−4.5 (−6.5 to −2.4)<0.0001
Body mass index−0.27 (−0.47 to −0.07)0.009
KCO, % predicted0.043 (0.01 to 0.08)0.04
  • Only variables which contributed significantly to the variance of serum 25-OHD in patients with COPD (n=252) are shown. Non-significant variables were removed from the model and are not shown. These include: current smoking, current and previous use of oral corticosteroids, age, gender and rs4588 variants.

  • COPD, chronic obstructive pulmonary disease; FEV1, forced expiratory volume in 1 s; KCO, alveolar ventilation; 25-OHD, 25-hydroxyvitamin D.