Table 1

Demograhpic characteristics of the included coal miners by occupational stress level indicated with Effort–Reward Imbalance (ERI) score (n=1334)

Total
(n=1334)
ERI >1
(n=1107)
ERI ≤1
(n=227)
P value
Sex, n (%)<0.001
 Male1173 (87.9)1040 (88.6)133 (11.4)
 Female161 (12.1)67 (41.6)94 (58.4)
Age, n (%)0.024
 ≤30202 (15.1)158 (78.2)44 (21.8)
 31–45575 (43.1)470 (81.7)105 (18.3)
 ˃45557 (41.8)479 (86.0)78 (14.0)
Working years, n (%)<0.001
 ≤15623 (46.7)488 (78.3)135 (21.7)
 ˃15711 (53.3)619 (87.1)92 (12.9)
Work type, n (%)0.073
 Coal digger266 (19.9)222 (83.5)44 (16.5)
 Driver72 (5.4)55 (76.4)17 (23.6)
 Electrical fitter274 (20.5)235 (85.8)39 (14.2)
 Hauler94 (7.0)74 (78.7)20 (21.3)
 Safety worker211 (15.8)165 (78.2)46 (21.8)
 Ground417 (31.3)356 (85.4)61 (14.6)
Working shift, n (%)0.900
 Fixed the day476 (35.7)398 (83.6)78 (16.4)
 Work on two shifts203 (15.2)168 (82.8)35 (17.2)
 Three shifts655 (49.1)541 (82.6)114 (17.4)
Level of education, n (%)<0.001
 Middle school or below671 (50.3)486 (72.4)185 (27.6)
 Middle school above663 (49.7)621 (93.7)42 (6.3)
Marital status, n (%)0.143
 Spinsterhood138 (10.3)107 (77.5)31 (22.5)
 First marriage1153 (86.4)966 (83.8)187 (16.2)
 Other43 (3.2)34 (79.1)9 (20.9)
Annual income, n (%)0.003
 ≤60 0001116 (83.7)941 (84.3)175 (15.7)
 ˃60 000218 (16.3)166 (76.1)52 (23.9)
Smoking, n (%)725 (54.3)602 (83.0)123 (17.0)0.957
Drinking, n (%)783 (58.8)650 (83.0)133 (17.0)0.972
  • Underground work professionals included coal diggers, drivers, electrical fitters, haulers and safety workers. Other marital statuses included remarriage, divorce and widowed.

  • P<0.05