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Table 1 General and occupational characteristics

From: Association between long working hours and serum gamma-glutamyltransferase levels in female workers: data from the fifth Korean National Health and Nutrition Examination Survey (2010-2011)

Variables Total Weekly working hours P-value
≤29 N (%*) 30–51 N (%*) ≥52 N (%*)
Total 1,809 (100.0) 400 (21.0) 1,054 (57.8) 355 (21.2)  
Age (years)      
 20-39 1,150 (65.0) 256 (64.8) 691 (67.5) 203 (58.6) 0.039
 40-49 659 (35.0) 144 (35.2) 363 (32.5) 152 (41.4)  
BMI (kg/m2)      
 Underweight (<18.5) 182 (10.8) 38 (10.3) 120 (12.2) 24 (7.4) 0.172
 Normal (18.5–22.9) 1,307 (71.1) 290 (70.6) 765 (71.1) 252 (71.4)  
 Overweight (≥23.0) 317 (18.1) 70 (19.1) 169 (16.7) 78 (21.2)  
Alcohol consumption (glasses/week)      
 ≤2.5 1,217 (66.3) 291 (72.5) 708 (65.5) 218 (62.1) 0.035
 >2.5 592 (33.7) 109 (27.5) 346 (34.5) 137 (37.9)  
Smoking status      
 Non-smoker 1,532 (82.3) 343 (86.1) 904 (82.4) 285 (78.3) 0.040
 Ex-smoker 136 (8.5) 30 (8.0) 76 (8.8) 30 (8.0)  
 Current smoker 141 (9.2) 27 (5.8) 74 (8.8) 40 (13.7)  
Sleep duration (hours/day)      
 ≤5 151 (9.0) 30 (8.7) 85 (9.0) 36 (9.4) 0.028
 6–8 1,527 (83.5) 327 (79.4) 897 (83.9) 303 (86.5)  
 ≥9 131 (7.5) 43 (11.9) 72 (7.2) 16 (4.1)  
Regular walking      
 Yes 658 (37.3) 152 (40.6) 388 (37.9) 118 (32.5) 0.135
 No 1,150 (62.7) 248 (59.4) 665 (62.1) 237 (67.5)  
Coffee intake (cups/day)      
 <1 504 (37.8) 87 (31.2) 304 (39.2) 113 (40.2) 0.130
 ≥1 840 (62.2) 200 (68.8) 479 (60.8) 161 (59.8)  
Working type      
 Day work 1,478 (81.6) 281 (67.1) 907 (85.6) 290 (85.0) <0.001
 Non-day work 317 (18.4) 117 (32.9) 141 (14.4) 59 (15.0)  
Occupation      
 Manual work 266 (15.6) 61 (16.4) 145 (14.8) 60 (17.1) 0.633
 Non-manual work 1,542 (84.4) 339 (83.6) 909 (85.2) 294 (82.9)  
Employment status      
 Salary worker 1,127 (73.8) 206 (64.7) 746 (81.9) 175 (60.8) <0.001
 Self-employed 289 (19.1) 87 (26.1) 108 (13.1) 94 (28.3)  
 Unpaid family worker 107 (7.2) 26 (9.2) 42 (5.0) 39 (10.9)  
  1. *Estimate percentage.
  2. χ2 test.