Table 4

Association between longitudinal changes in LF and cross-shift change in FEV1 stratified by wood dust exposure, smoking, atopic status and place of participation adjusted for confounders in linear regression analyses

Independent variablesSubjects included (missing)LF changes at follow-up
ΔFEV1 ml/yearΔFVC ml/year
Coefficient (95% CI)*Coefficient (95% CI)*
Stratified by exposure†
 ΔFEV1 cross-shift %‡806−0.29 (−0.74 to 0.16)0.13 (−0.35 to 0.61)
 Woodworkers(11)
 ΔFEV1 cross-shift %‡129−0.29 (−1.80 to 1.23)0.55 (−1.07 to 2.17)
 Control workers(7)
Stratified by smoking§
 ΔFEV1 cross-shift %‡412−0.67 (−1.34 to 0.01)−0.15 (−0.89 to 0.60)
 +Smokers¶(4)
 ΔFEV1 cross-shift %‡5230.01 (−0.53 to 0.56)0.40 (0.17 to 0.97)
 −Smokers¶(7)
Stratified by atopy†§
 ΔFEV1 cross-shift %‡135−0.48 (−1.27 to 0.32)−0.35 (−1.28 to 0.58)
 +Atopyf(3)
 ΔFEV1 cross-shift %‡583−0.43 (−0.96 to 0.09)0.13 (−0.41 to 0.66)
 −Atopyf(12)
Stratified by place of participation†§
 ΔFEV1 cross-shift %‡644−0.21 (−0.78 to 0.35)0.44 (−0.19 to 1.07)
 +Factory**(11)
 ΔFEV1 cross-shift %‡291−0.31 (−0.93 to 0.30)−0.19 (−0.80 to 0.41)
 −Factory**(7)

  • ΔFEV1% have the same direction as LF changes at follow-up, that is, a positive regression coefficient indicates an association between decline in cross-shift FEV1 and longitudinal LF.

  • *Additional variables adjusted for in all the models: height (continuous), weight-gain (continuous) and age (continuous).

  • †Adjusted ± smoking.

  • §Adjusted ± wood dust exposure at baseline.

  • ‡Cross-shift change FEV1 baseline.

  • ¶Smokers are current smokers and ex-smokers who stopped smoking <2 years prior to baseline.

  • fAtopic status at follow-up.

  • **Participation on factory versus invitation by letter.

  • LF, lung function; ΔFEV1, change in forced expiratory volume in 1 s; ΔFVC, change in forced vital capacity.