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Table 1 Characteristics of participants

From: Sleep duration, snoring habits and risk of acute myocardial infarction in China population: results of the INTERHEART study

Characteristics AMI cases, N = 2909 Controls, N = 2947 χ 2/Z P-value
Male sex (%) 2027 (69.7) 2048 (69.5) 0.02 0.8771
Mean Age (SD), year 62.1 (11.7) 60.3 (11.4) 6.28 0.0001
BMI, n (%)    18.40 0.0001
     ≤ 24 1173 (40.3) 1341 (45.5)   
     24-28 1358 (46.7) 1291 (43.8)   
     > 28 378 (13.0) 315 (10.7)   
WHR, mean (SD), cm/cm 0.88 (0.08) 0.88 (0.08) 2.16 0.2011
Hypertension (%) 1145 (39.5) 656 (22.26) 203.68 0.0001
Diabetes (%) 360 (12.4) 87 (3.0) 185.54 0.0001
Stroke (%) 317 (10.9) 102 (3.5) 122.76 0.0001
Family history of MI, n (%) 102 (3.5) 54 (1.8) 15.93 0.0001
Smoking, n (%) 1694 (58.2) 1186 (40.2) 189.54 0.0001
Alcohol, n (%) 463 (15.9) 429 (14.6) 2.09 0.1479
Physical activity, n (%) 128 (14.8) 558 (19.0) 17.93 0.0001
Educational status, n (%)    52.57 0.0001
     Trade school/college/university 553 (19.1) 723 (24.5)   
     9-12 years 799 (27.5) 924 (31.4)   
     ≤ 8 years 1546 (53.4) 1300 (44.1)   
Income    10.72 0.0047
     Higher 1021 (35.3) 1157 (39.2)   
     Middle 928 (32.0) 907 (30.8)   
     Lower 941 (32.7) 875 (30.0)   
Single or divorced, n (%) 366 (12.6) 197 (6.7) 58.81 0.0001
General stress, n (%)    20.33 0.0001
     Permanent 1083 (37.4) 944 (32.0)   
     Several periods 1311 (45.3) 1411 (47.9)   
     Never experienced 500 (17.3) 591 (20.1)   
Depressed, n (%) 559 (19.6) 273 (9.3) 122.88 0.0001
Consumption of vegetables (times/week) 7.8 (5.5) 7.9 (5.4) −1.10 0.2705
Consumption of fruits (times/week) 4.0 (3.7) 4.8 (3.7) −9.29 0.0001
  1. N, number; p-value, significance of difference between group means and frequency determined by rank-test and chi-square test.