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Table 1 General characteristics of the study population

From: The association between long working hours and hearing impairment in noise unexposed workers: data from the 5th Korea National Health and Nutrition Examination Survey (KNHANES 2010–2012)

Variables Total   Male   Female   p-value
na nb(%c) na nb(%c) na nb(%c)
Total 1628 3780449(100.0) 768 2030862(100.0) 860 1749588(100.0)  
Age (years)
 Mean ± SE 40.0 ± 0.3   40.3 ± 0.4   39.6 ± 0.4   0.174
 25–34 444 1246970(33.0) 165 610588(30.1) 279 636382(36.4) 0.069
 35–44 603 1368113(36.2) 311 791293(39.0) 292 576820(33.0)  
 45–54 394 858442(22.7) 193 469842(23.1) 201 388600(22.2)
 55–64 187 306924(8.1) 99 159138(7.8) 88 147786(8.4)
BMI (kg/m2)
 Underweight 72 153504(4.1) 8 20560(1.0) 64 132944(7.6) <0.001
 Normal 1092 2480000(65.6) 454 1190804(58.6) 638 1289196(73.7)  
 Obese 464 1146946(30.3) 306 819498(40.4) 158 327448(18.7)
Education
  ≤ Middle school 170 362359(9.6) 58 151184(7.4) 112 211175(12.1) 0.003
 High school 564 1427402(37.8) 252 725608(35.7) 312 701795(40.1)  
  ≥ College 894 1990688(52.7) 458 1154070(56.8) 436 836618(47.8)
Marital status
 Never married 254 753440(19.9) 82 335275(16.5) 172 418165(23.9) <0.001
 Married 1289 2817011(74.5) 672 1653806(81.4) 617 1163205(66.5)  
 Others 85 209998(5.6) 14 41780(2.1) 71 168218(9.6)
Household income
 Low 56 162234(4.3) 19 73594(3.6) 37 88640(5.1) 0.017
 Mid-low 381 1008432(26.7) 207 621443(30.6) 174 386988(22.1)  
 Mid-high 576 1368482(36.2) 271 720932(35.5) 305 647550(37.0)
 High 615 1241302(32.8) 271 614892(30.3) 344 626410(35.8)
Smoking
 Non-smoker 967 2044875(54.1) 181 478096(23.5) 786 1566780(89.6) <0.001
 Ex-smoker 267 638628(16.9) 236 570841(28.1) 31 67787(3.9)  
 Current smoker 394 1096946(29.0) 351 981925(48.4) 43 115022(6.6)
Alcohol
 None 269 549452(14.5) 80 212616(10.5) 189 336836(19.3) <0.001
 Light drinker 1123 2586279(68.4) 500 1290078(63.5) 623 1296201(74.1)  
 Heavy drinker 236 644718(17.1) 188 528167(26.0) 48 116551(6.7)
Exercise
 No 1335 3060829(81.0) 619 1602748(78.9) 716 1458080(83.3) 0.051
 Yes 293 719621(19.0) 149 428113(21.1) 144 291507(16.7)  
Job type
 Non-manual 1278 2857188(75.6) 554 1401179(69.0) 724 1456009(83.2) <0.001
 Manual 350 923262(24.4) 214 629683(31.0) 136 293579(16.8)  
Shift work
 No 1373 3172611(83.9) 646 1730392(85.2) 727 1442219(82.4) 0.239
 Yes 255 607838(16.1) 122 300469(14.8) 133 307369(17.6)  
Weekly working hours
 Mean ± SE 47.0 ± 0.3 49.2 ± 0.5 44.5 ± 0.5 <0.001
  ≤ 40 673 1460816(38.6) 243 625000(30.8) 430 835816(47.8) <0.001
 40 < x ≤ 48 401 930976(24.6) 176 480684(23.7) 225 450292(25.7)  
 48 < x ≤ 60 399 1007298(26.6) 248 669145(32.9) 151 338153(19.3)
  > 60 155 381360(10.1) 101 256032(12.6) 54 125328(7.2)
  1. SE standard error
  2. aunweighted count, bestimated population size, ccolumn and estimated percentage