Table 1 Distribution of the exposure and covariates considered in the analysis.
Variable | Category | 1990 (N = 2947) | 1995 (N = 2691) | 2000 (N = 2566) |
|---|---|---|---|---|
WBV | 9.8 | 9.7 | 9.2 | |
Age (mean) | 37.4 | 37.9 | 39.2 | |
Smoking | Heavy smokers | 32.4 | 29.1 | 27.5 |
Moderate smokers | 17.3 | 14.8 | 12.7 | |
Ex-smokers | 18.9 | 20.6 | 22.4 | |
Never-smoked | 31.5 | 35.6 | 37.5 | |
BMI | Underweight | 0.6 | 0.7 | 0.5 |
Normal | 61.0 | 56.0 | 51.3 | |
Overweight | 32.6 | 36.4 | 38.8 | |
Obese | 5.8 | 6.9 | 9.4 | |
Physically hard work | 16.8 | 16.1 | 13.9 | |
Working with hands above shoulders | 17.3 | 13.9 | 17.0 | |
Squatting or kneeling | 17.7 | 12.9 | 14.5 |