Table 1:
Summary of characteristics of studies included in the systematic review
| Ref | Language | Type of factory | type of study | Sample size | ONIHL (%) | Gender | Age (mean ± SD) | Work experience (mean ± SD) |
|---|---|---|---|---|---|---|---|---|
| (28) | English | Driver | cross-sectional | 2283 | 41.8 | male | 39±10 | 14±9.3 |
| (15) | English | Automobile company | cross-sectional | 478 | 60.5 | male | 33.51±5.35 | - |
| (29) | English | Driver (long-distance) | cross-sectional | 4300 | 18.1 | male | 40.8±11 | 14.7±9.6 |
| (30) | English | Truck drivers | cross-sectional | 500 | 42 | male | 38±12.2 | 9.8±8.6 |
| (31) | English | Wagon manufacturing | cross-sectional | 504 | 39.5 | male | 42.25±6.56 | 18.14±6.5 |
| (14) | English | Heavy vehicle drivers | cross-sectional | 65533 | 14.6 | male | - | - |
| (32) | English | Food-producing factory | cross-sectional | 412 | 41.01 | male | - | - |
| (33) | English | Home appliances factory | cross-sectional | 371 | 55.25 | male | 32.17±4.92 | 6.65±2.74 |
| (34) | English | Tile and Ceramic Industry | cross-sectional | 853 | 17.4 | male | 32.95±7.15 | 5.95±4.62 |
| (35) | English | Drivers | cross-sectional | 1900 | 39.6 | male | 41.5±10.5 | - |
| (17) | Persian | Textile spinning | cross-sectional | 100 | 21 | male | - | - |
| (18) | Persian | Oil industry | cross-sectional | 110 | 49 | male | - | - |
| (19) | Persian | Airport | cross-sectional | 106 | 33 | male | 34.86±8.37 | 10.6±7.44 |
| (36) | English | Professional drivers | cross-sectional | 1901 | 49.65 | male | 41.56±10.57 | - |
| (20) | Persian | Car smoothing workshops | cross-sectional | 50 | 36 | male | 38.7±9.7 | 21.5±9.6 |
| (21) | Persian | Manufacturing industries | cross-sectional | 2004 | 22.5 | male | - | - |
| (37) | English | Fireclay mine | cross-sectional | 220 | 23.63 | male | 38±6.4 | - |
| (38) | English | Derivers | cross-sectional | 1000 | 42.6 | male | 34.02±13.9 | 8.21±7.84 |
| (22) | Persian | Tire manufacturing company | cross-sectional | 914 | 32.7 | male | 38.84±5.18 | 12.37±4.12 |
| (23) | Persian | Textile | cross-sectional | 100 | 23.25 | male | 38.98±10.43 | 13.83±6.1 |
| (39) | English | Automobile industry | cross-sectional | 441 | 49.88 | male | 33.07 | 8.06 |
| (16) | English | Petrochemical industry | cross-sectional | 280 | 23.21 | male | - | - |
| (24) | Persian | Agriculture factory | case-control | 131 | 36.69 | male | - | 19.6±8.4 |
| (25) | Persian | Metal workers | cross-sectional | 743 | 31.31 | male | - | - |
| (26) | Persian | Tile factory | cross-sectional | 342 | 12.9 | male | 37.3±8.1 | 10.6±6.9 |
| (27) | Persian | Small manufacturing industries | cross-sectional | 109 | 46.8 | male | - | - |