Table 4– Unadjusted and adjusted change in mean standardised residual# per 10-fold increase in endotoxin level for forced expiratory volume in 1 s (FEV1), forced vital capacity (FVC) and FEV1/FVC and endotoxin levels for the entire sample and stratified by CD14 genotype
ParticipantsCD14/-260 genotypep-value
AllFull confounder informationFull confounders and genotypeCCCTTTHeterogeneity of effectTrend of interaction
Participants n902814527110271146
FEV1
 Unadjusted-0.01 (-0.16–0.15)0.01 (-0.15–0.18)0.07 (-0.11–0.26)0.51 (0.11–0.92)0.04 (-0.21–0.30)-0.24 (-0.61–0.11)0.0200.003
 Adjusted+0.04 (-0.11–0.19)0.08 (-0.11–0.27)0.62§ (0.21–1.04)0.01 (-0.25–0.27)-0.22 (-0.59–0.13)0.0080.005
FVC
 Unadjusted-0.09 (-0.24–0.06)-0.06 (-0.22–0.09)-0.02 (-0.22–0.16)0.31 (-0.14–0.77)-0.03 (-0.30–0.23)-0.33 (-0.68–0.02)0.0080.059
 Adjusted+-0.05 (-0.22–0.10)0.00002 (-0.20–0.20)0.49 (0.03–0.96)-0.04 (-0.32–0.23)-0.29 (-0.65–0.06)0.0290.013
FEV1/FVC
 Unadjusted0.15 (0.02–0.29)0.15 (0.01–0.29)0.14 (-0.03–0.31)0.24 (-0.16–0.65)0.09 (-0.14–0.33)0.20 (-0.11–0.52)0.7750.976
 Adjusted+0.13 (-0.01–0.27)0.13 (-0.005–0.28)0.18 (-0.24–0.60)0.05 (-0.18–0.29)0.27 (-0.03–0.59)0.5380.809
  • Data are presented with 95% confidence intervals. #: a male of age 50 yrs and height of 180 cm is predicted to have a FEV1 of 3.8 L using the equation of Quanjer et al. [17]. If his observed FEV1 is 4 L, then the difference between observed and predicted FEV1 is 0.2 L. Following standardisation (again using the standard deviation provided by Quanjer et al. [17]), his standardised residual is 0.38. This means the difference between his measured and predicted FEV1 is 0.38 standard deviations greater than the mean of all of these values. : assuming additive model. +: confounders were smoking status in pack-yrs and household variables (keeping a cat or dog, age of the mattress, presence of mould in bedroom, presence of damp in bedroom, household density and age of home). §: a coefficient of 0.62 in this table means that for a 10-fold increase in endotoxin levels (it is 10-fold because endotoxin levels have been logarithmically transformed using base 10) there is a change of 0.62 standard deviations in the difference between measured and predicted FEV1.