Mean values for lung function test variables at baseline and follow-up evaluations are shown in Table 2. The absolute mean across-shift reductions (± SD) in FEV1 and FVC were -159.8±204.2 mL and -35.3±65.6 mL, respectively. When expressed as the percentage change of baseline evaluations, the changes were-3.8±5.1% and-0.6±1.2% for FEV1 and FVC, respectively. Over the study period, mean annual rate changes in FEV1 and FVC were -53.9±61.7 mL/year and -48.9±71.6 mL/year, respectively. Environmental measurements for both study periods in the participating confinement facilities are shown in Table 3.

Relationships between the percentage shift change and annual rate change are shown for FEV1 in Figure 1 and for FVC in Figure 2. Correlation coefficients between the percentage shift change and annual rate change for FEV 1 and FVC were 0.34 (P=0.03) and 0.38 (P=0.01), respectively.

Figure 1) Relationship between the annual rate change and percentage shift change in forced expiratory capacity in 1 s (FEV1). Straight line indicates linear regression of annual rate change on the percentage shift change (Pearson correlation r=0.34, P=0.03)

Figure 2) Relationship between the annual rate change and percentage shift change inforcd vital capacity (FVC). Straight line indicates linear regression of annual rate change on the percentage shift change (r=0.38, P=0.01)

Table 2. Lung function measurement at baseline and follow-up for swine confinement workers

Table 3. Environmental measurements

Relationships between the percentage shift change and annual rate change are shown for FEV1 in Figure 1 and for FVC in Figure 2. Correlation coefficients between the percentage shift change and annual rate change for FEV 1 and FVC were 0.34 (P=0.03) and 0.38 (P=0.01), respectively.

Relationships between the percentage shift change and annual rate change are shown for FEV1 in Figure 1 and for FVC in Figure 2. Correlation coefficients between the percentage shift change and annual rate change for FEV 1 and FVC were 0.34 (P=0.03) and 0.38 (P=0.01), respectively.