Table 2

Crude and adjusted mean PTS from the first to last hearing examination by sex, age and occupation

CrudeAdjusted
NumberPTS346, dB (95% CI)PTS0.5124, dB (95% CI)PTS346, dB (95% CI)PTS0.5124, dB (95% CI)
Sex
 Women9763.1 (2.6 to 3.7)Ref1.8 (1.4 to 2.1)Ref5.7 (5.2 to 6.2)Ref2.9 (2.6 to 3.2) Ref
 Men75947.5 (7.3 to 7.7)***3.2 (3.1 to 3.3)***7.2 (7.0 to 7.3)***3.0 (2.9 to 3.1)
Age (years)‡§
 <3620962.4 (2.1 to 2.8)Ref0.9 (0.7 to 1.2)Ref4.4 (4.0 to 4.7)Ref1.7 (1.5 to 1.9)Ref
 36 to 4421196.5 (6.1 to 6.9)***2.6 (2.3 to 2.8)***5.6 (5.3 to 5.9)***2.2 (2.0 to 2.4)***
 44–5021219.6 (9.2 to 10.0)***4.1 (3.9 to 4.3)***8.0 (7.7 to 8.3)***3.5 (3.2 to 3.7)***
 >5022349.3 (8.9 to 9.7)***4.4 (4.1 to 4.6)***9.9 (9.5 to 10.2)***4.6 (4.4 to 4.8)***
Occupation
 Traffic controller5227.1 (6.3 to 7.9)Ref2.8 (2.3 to 3.2)Ref6.3 (5.7 to 7.0)Ref2.4 (1.9 to 2.8)Ref
 Train driver13227.6 (7.2 to 8.1)3.3 (3.0 to 3.6)6.8 (6.3 to 7.2)3.0 (2.7 to 3.3)
 Train conductor11735.7 (5.2 to 6.2)2.5 (2.2 to 2.8)7.1 (6.6 to 7.5)3.1 (2.8 to 3.4)
 Bus driver6965.0 (4.3 to 5.7)**2.0 (1.5 to 2.4)6.8 (6.2 to 7.4)2.6 (2.2 to 3.0)
 Train maintenance12927.4 (6.9 to 7.9)3.3 (3.0 to 3.6)7.0 (6.6 to 7.4)3.1 (2.8 to 3.4)
 Track maintenance18889.0 (8.6 to 9.3)*3.8 (3.5 to 4.0)**7.6 (7.2 to 7.9)**3.2 (3.0 to 3.5)*
 Others16775.6 (5.2 to 6.1)*2.6 (2.4 to 2.9)6.8 (6.4 to 7.2)3.1 (2.8 to 3,3)
Total8570
  • Better ear. Same occupation at the first and last audiograms.

  • *p<0.05; **p<0.01; ***p<0.001.

  • †Adjusted for age, duration of follow-up and occupation.

  • ‡Mean age of the follow-up period by quartiles.

  • §Adjusted for sex, duration of follow-up and occupation.

  • ¶Adjusted for age, sex and duration of follow-up.

  • PTS, permanent threshold shift.