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Table 1 Basic Information Distribution in Case and Control Groups

From: Effect of GRM7 polymorphisms on the development of noise-induced hearing loss in Chinese Han workers: a nested case-control study

Variables Case (n = 292) Control (n = 584) Statistics p
Age, year
 20~30 45 (15.4%) 104 (17.8%)   
 30~40 79 (27.1%) 153 (26.2%)   
 40~50 134 (45.9%) 270 (46.2%)   
 50~60 34 (11.6%) 57(9.8%) 1.381 0.710
Noise exposure duration, year 18.860 (8.500, 27.750) 18.509 (8.167, 26.917) −0.692§ 0.489
CNE, dB(A)* 97.844 (94.686, 101.522) 97.767 (94.854, 101.195) −0.153§ 0.878
HTL, dB(A) 50.980 (44.042, 55.833) 18.293 (12.500, 24.000) −24.153§ <0.001
Height, cm 170.366 (167.000, 174.750) 169.993 (166.000, 174.000) −1.004§ 0.315
Gender
 Male 281 (96.2%) 560 (95.9%)   
 Female 11 (3.8%) 24 (4.1%) 0.060 0.807
level of environmental noise exposure, dB(A)
  ≤ 85 121 (41.4%) 254 (43.5%)   
  > 85 171 (58.6%) 330 (56.5%) 0.336 0.562
Tinnitus
 Yes 196 (67.4%) 316 (54.2%)   
 No 95 (32.6%) 267 (45.8%) 12.837 <0.001
Smoking
 Yes 181 (62.0%) 341 (58.4%)   
 No 109 (38.0%) 243 (41.6%) 1.045 0.307
Drinking
 Yes 203 (69.5%) 399 (68.3%)   
 No 89 (30.5%) 185 (31.7%) 0.130 0.718
Hypertension
 Yes 112 (38.4%) 242 (41.4%)   
 No 180 (61.6%) 342 (58.6%) 0.768 0.381
  1. Evaluation of the matching effects in the case and control groups by comparing the basic information distribution between them
  2. *CNE: cumulative noise exposure
  3. HTL: the binaural average hearing threshold level in high frequencies
  4. Pearson chi-square test
  5. §Wilcoxon rank sum test