Table 3

Results summary from mixed models at dominant and non-dominant second and fifth fingers at seven test frequencies: associations between HAV exposure from rock drills and VPT; coefficients represent increase of VPT (dB) per 10-fold increase in last 12 months of exposure before tests (hour×ms–2) †‡

FrequencyDominant second finger
(n=147, number of obs=248)§¶		Dominant fifth finger
(n=146, number of obs=244)§¶		Non-dominant second finger
(n=144, number of obs=242)§¶		Non-dominant fifth finger
(n=147, number of obs=246)§¶
HzCoefficients (95% CI)**Coefficients (95% CI)**Coefficients (95% CI)**Coefficients (95% CI)**
80.37 (–0.23 to 0.98)0.46 (–0.18 to 1.11)0.46 (–0.09 to 1.01)0.11 (–0.50 to 0.73)
160.54 (–0.05 to 1.12)0.56 (–0.05 to 1.18)0.47 (–0.17 to 1.11)0.37 (–0.22 to 0.97)
320.50 (–0.06 to 1.06)0.79 (0.16 to 1.42)*0.51 (–0.10 to 1.13)0.47 (–0.15 to 1.10)
640.26 (–0.46 to 0.98)0.37 (–0.34 to 1.08)0.34 (–0.43 to 1.11)0.79 (0.04 to 1.54)*
1250.63 (–0.16 to 1.43)0.54 (–0.34 to 1.43)0.34 (–0.49 to 1.17)1.06 (0.11 to 2.02)*
2500.51 (–0.38 to 1.40)0.99 (–0.07 to 2.10)0.48 (–0.49 to 1.45)1.21 (0.15 to 2.28)*
5001.14 (0.15 to 2.14)*1.51 (0.30 to 2.72)*1.62 (0.46 to 2.79)*1.53 (0.35 to 2.72)*

  • *P≤0.05.

  • †Log10-transformed exposure was used in models adjusted for age in 10-year intervals.

  • ‡HAV exposure was calculated as lifetime cumulative exposure at each VPT test. Subject ID was used as random intercept in linear mixed models.

  • §Each subject was tested for VPT 1–3 three times (mean 1.7 times) with approximately 2 years between each test.

  • ¶The number of participants is less than the total of n=148 for each tested finger because of participants having injured or missing fingertips.

  • **Rock drill exposure was adjusted for impact wrench exposure in the models.

  • HAV, hand-arm vibration; VPT, vibration perception thresholds .