Table 2.
Demographic and occupational characteristics involved in this study.
| Variables | Stage I (n = 3,193) | Stage II (n = 777) | Stage III (n = 133) | F | p | |||
|---|---|---|---|---|---|---|---|---|
| N | % | N | % | N | % | |||
| Age (years), mean ± SD | 72.34 ± 8.20 | 73.28 ± 9.02 | 70.47 ± 12.08 | 7.60 | <0.001 | |||
| <50 | 25 | 0.78 | 12 | 1.54 | 7 | 5.26 | ||
| 50–60 | 275 | 8.61 | 57 | 7.34 | 19 | 14.29 | ||
| 60–70 | 646 | 20.23 | 146 | 18.79 | 32 | 24.06 | ||
| ≥70 | 2,247 | 70.37 | 562 | 72.33 | 75 | 56.39 | ||
| Gender | 10.35 | <0.001 | ||||||
| Male | 3,151 | 98.68 | 773 | 99.49 | 128 | 96.24 | ||
| Female | 42 | 1.32 | 4 | 0.51 | 5 | 3.76 | ||
| Industry category | 82.43 | <0.001 | ||||||
| Mining | 2,284 | 71.53 | 672 | 86.48 | 88 | 66.17 | ||
| Manufacturing | 575 | 18.01 | 57 | 7.34 | 26 | 19.55 | ||
| Public management and social security | 318 | 9.87 | 47 | 6.05 | 19 | 14.29 | ||
| Others | 19 | 0.60 | 1 | 0.13 | 0 | 0.00 | ||
| Economic level | 75.31 | <0.001 | ||||||
| High level | 2,484 | 77.80 | 678 | 87.26 | 77 | 57.89 | ||
| Medium level | 398 | 12.46 | 61 | 7.85 | 26 | 19.55 | ||
| Low level | 311 | 9.74 | 38 | 4.89 | 30 | 22.56 | ||
| Enterprise size | 158.56 | <0.001 | ||||||
| Big | 2,352 | 73.66 | 665 | 85.59 | 74 | 55.64 | ||
| Middle | 407 | 12.75 | 34 | 4.38 | 12 | 9.02 | ||
| Small or micro | 115 | 3.60 | 31 | 3.99 | 27 | 20.30 | ||
| Others | 319 | 9.99 | 47 | 6.05 | 20 | 15.04 | ||
| Dust exposure duration (years), mean ± SD | 17.53 ± 7.66 | 17.14 ± 5.98 | 15.49 ± 7.37 | 5.46 | 0.004 | |||
| <10 | 622 | 19.48 | 101 | 13.00 | 35 | 26.32 | ||
| 10–20 | 1,428 | 44.72 | 482 | 62.03 | 73 | 54.89 | ||
| 20–30 | 999 | 31.29 | 183 | 23.55 | 19 | 14.29 | ||
| 30–40 | 128 | 4.01 | 7 | 0.90 | 6 | 4.51 | ||
| ≥40 | 16 | 0.50 | 4 | 0.51 | 0 | 0.00 | ||
| Types | 102.36 | <0.001 | ||||||
| Silicosis | 1,968 | 61.63 | 615 | 79.15 | 107 | 80.45 | ||
| CWP | 1,000 | 31.32 | 140 | 18.02 | 18 | 13.53 | ||
| Welder’s pneumoconiosis | 53 | 1.66 | 8 | 1.03 | 2 | 1.50 | ||
| Others | 172 | 5.39 | 14 | 1.80 | 6 | 4.51 | ||
| First diagnostic stage | 3300.00 | <0.001 | ||||||
| Stage I | 3,193 | 100.00 | 520 | 66.92 | 50 | 37.59 | ||
| Stage II | 0 | 0.00 | 257 | 33.08 | 10 | 7.52 | ||
| Stage III | 0 | 0.00 | 0 | 0.00 | 73 | 54.89 | ||
| Age of onset (years), mean ± SD | 48.74 ± 9.23 | 45.15 ± 8.79 | 49.92 ± 12.62 | 49.43 | <0.001 | |||
| 10–20 | 3 | 0.09 | 1 | 0.13 | 1 | 0.75 | ||
| 20–30 | 38 | 1.19 | 15 | 1.93 | 3 | 2.26 | ||
| 30–40 | 360 | 11.27 | 181 | 23.29 | 28 | 21.05 | ||
| ≥40 | 2,792 | 87.44 | 580 | 74.65 | 101 | 75.94 | ||
| Upgrade of stages of pneumoconiosis | 4400.00 | <0.001 | ||||||
| Stable stages | 3,193 | 100.00 | 257 | 33.08 | 73 | 54.89 | ||
| Upgrade I to II | 0 | 0.00 | 520 | 66.92 | 0 | 0.00 | ||
| Upgrade II to III | 0 | 0.00 | 0 | 0.00 | 37 | 27.82 | ||
| Upgrade I to III | 0 | 0.00 | 0 | 0.00 | 23 | 17.29 | ||
| Social security | 162.95 | <0.001 | ||||||
| Deny | 771 | 24.15 | 297 | 38.22 | 85 | 63.91 | ||
| Employment injury insurance | 1,533 | 48.01 | 258 | 33.20 | 27 | 20.30 | ||
| Medical insurance | 889 | 27.84 | 222 | 28.57 | 21 | 15.79 | ||
| Degree of disability | 2000.00 | <0.001 | ||||||
| Unrated | 752 | 23.55 | 279 | 35.91 | 79 | 59.40 | ||
| ≤Level 7 | 2,242 | 70.22 | 46 | 5.92 | 3 | 2.26 | ||
| Level 7–4 | 197 | 6.17 | 441 | 56.76 | 31 | 23.31 | ||
| >Level 4 | 2 | 0.06 | 11 | 1.42 | 20 | 15.04 | ||
| Survival time (years), mean ± SD | 23.59 ± 9.10 | 28.13 ± 10.38 | 20.55 ± 13.50 | 81.93 | <0.001 | |||
| Outcome variables | 144.64 | <0.001 | ||||||
| Dead | 770 | 24.12 | 296 | 38.10 | 84 | 63.16 | ||
| Survival | 2,423 | 75.88 | 481 | 61.90 | 49 | 36.84 | ||
SD, standard deviation.