Table 3 Covariance analysis of FVC%, FEV1%, FEV1/FVC% in different PPD-exposure group (mean ± SD).

From: Association of p-phenylenediamine exposure with alterations of pulmonary function, pruritus and health-related quality of life in hair dye factory workers: a cross-sectional study

Variable

Lower exposure (n = 24)

Middle exposure (n = 50)

Higher exposure (n = 50)

F

P value

FVC%

103.044 ± 9.498

89.076 ± 11.806*#

101.399 ± 9.409

7.519

 < 0.001

FEV1%

104.665 ± 12.289

91.772 ± 6.261*

92.483 ± 10.300*

8.791

 < 0.001

FEV1/FVC%

102.215 ± 14.040

104.700 ± 14.779#

91.889 ± 12.737*

6.855

 < 0.001

  1. Measurement indexes of capacity and the volume of lung include forced vital capacity (FVC), forced expiratory volume in one second (FEV1), and ratio of FEV1 to FVC (FEV1/FVC), etc. Abnormal pulmonary function is defined as: FVC% (percentage of forced vital capacity, FVC measured value/FVC predicted value) < 80%; FEV1% (percentage of forced expiratory volume in 1 s, FEV1 measured value/FEV1 predicted value) < 75%; FEV1/FVC%, FEV1 measured value/FVC measured value < 70%. The predictive values of FVC or FEV1 is automatically calculated by the pulmonary function analyzer according to age, gender, height, weight and race.
  2. *P < 0.05, comparison of the higher and middle exposure group with the lower exposure group by Bonferroni method.
  3. #P < 0.05, comparison between the higher exposure group and middle exposure group by Bonferroni method.
  4. The covariant variables including gender, ethnic group, working age, education condition and recent hair dye history.
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