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Table 1 Baseline characteristics of the study population in the 2015–2017 KNHANES

From: Sex differences in the association between self-rated health and high-sensitivity C-reactive protein levels in Koreans: a cross-sectional study using data from the Korea National Health and Nutrition Examination Survey

Characteristic Men Women
Low hs-CRP (≤ 1.0 mg/L) (n = 4495) High hs-CRP (> 1.0 mg/L) (n = 1786) P value Low hs-CRP (≤ 1.0 mg/L) (n = 6306) High hs-CRP (> 1.0 mg/L) (n = 1957) P value
Age (years), mean (SD) 49.8 (0.249) 53.3(0.391) .000* 49.9 (0.203) 54.2 (0.373) .000*
Educational level, n (%)    .000*    .000*
 Elementary school or lower 580 (12.9) 333 (18.6)   1424 (22.6) 653 (33.4)  
 Middle school 446 (9.9) 205 (11.5)   651 (10.3) 203 (10.4)  
 High school 1575 (35.0) 568 (31.8)   2001 (31.7) 547 (28.0)  
 College or higher 1894 (42.1) 680 (38.1)   2230 (35.4) 554 (28.3)  
Marital status, n (%)    .002*    .000*
 Married 3536 (78.7) 1487 (83.3)   5396 (85.6) 1772 (90.5)  
 Unmarried 959 (21.3) 299 (16.7)   910 (14.4) 185 (9.5)  
Household income level, n (%)    .101    .009*
 Low 1034 (23.0) 457 (25.6)   1444 (22.9) 522 (26.7)  
 Lower middle 1077 (24.0) 464 (26.0)   1591 (25.2) 519 (26.5)  
 Upper middle 1156 (25.7) 435 (24.4)   1609 (25.5) 470 (24.0)  
 High 1228 (27.3) 430 (24.1)   1662 (26.4) 446 (22.8)  
Weight (kg), mean (SD) 70.0 (0.158) 73.4 (0.351) .000* 56.8 (0.103) 62.1 (0.253) .000*
Height (cm), mean (SD) 170.5 (0.101) 169.6 (0.161) .000* 157.5 (0.081) 156.2 (0.149) .000*
BMI (kg/m2), mean (SD) 24.0 (0.044) 25.4 (0.087) .000* 22.9 (0.040) 25.4 (0.091) .000*
Smoking, n (%)    .123    .483
 Nonsmoker 1130 (25.1) 389 (21.8)   5710 (90.5) 1742 (89.0)  
 Past smoker 1926 (42.8) 777 (43.5)   341 (5.4) 118 (6.0)  
 Current smoker 1439 (32.0) 620 (34.7)   255 (4.0) 97 (5.0)  
Alcohol consumption, n (%)    .001*    .000*
 Never drink 196 (4.4) 85 (4.8)   951 (15.1) 392 (20.0)  
 < Once/month 1004 (22.3) 457 (25.6)   2634 (41.8) 864 (44.1)  
 < Five times/month 1691 (37.6) 577 (32.3)   2020 (32.0) 496 (25.3)  
 ≥ Five times/month 1604 (35.7) 667 (37.3)   701 (11.1) 205 (10.5)  
Chronic diseases**, n (%)    .000*    .000*
 None 2579 (57.4) 789 (44.2)   4000 (63.4) 966 (49.4)  
 One 1186 (26.4) 590 (33.0)   1274 (20.2) 536 (27.4)  
 Two or more 730 (16.2) 407 (22.8)   1032 (16.4) 455 (23.2)  
Self-rated health, n (%)    .000*    .000*
 Very poor 80 (1.8) 59 (3.3)   270 (4.3) 108 (5.5)  
 Poor 532 (11.8) 264 (14.8)   1026 (16.3) 410 (21.0)  
 Fair 2271 (50.5) 943 (52.8)   3328 (52.8) 1009 (51.6)  
 Good 1317 (29.3) 431 (24.1)   1431 (22.7) 370 (18.9)  
 Very good 295 (6.6) 89 (5.0)   251 (4.0) 60 (3.1)  
Menopause, n (%)       .000*
 No     3211 (50.9) 752 (38.4)  
 Yes     3072 (48.7) 1189 (60.8)  
  1. KNHANES Korea National Health and Nutrition Examination Survey, SE standard error, SD standard deviation, BMI body mass index
  2. *p ≤ .05
  3. **Chronic diseases include hypertension, diabetes, dyslipidemia, coronary heart disease (myocardial infarction or angina pectoris), stroke, and rheumatoid arthritis
  4. P values of t test or the Mann–Whitney U test for continuous variables and Pearson’s chi-squared test for categorical variables to determine differences between groups according to high-sensitivity C-reactive protein (hs-CRP) levels