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Table 1 Baseline characteristics of study participants by sex (n = 258,367)

From: Association between serum lipids and low back pain among a middle-aged Japanese population: a large-scale cross-sectional study

  Men (n = 169,606) Women (n = 88,761) p valuea
n % n %
Age (years)
 40–49 80,774 47.6 40,029 45.1 <  0.001
 50–59 61,948 36.5 34,912 39.3  
 60–64 26,884 15.9 13,820 15.6  
Height (cm) 169.1 (6.4) 157.2 (6.3) <  0.001
Weight (kg) 68.5 (11.6) 55.7 (10.3) <  0.001
Body mass index (kg/m2)
 <  18.5 3783 2.2 6241 7.0 <  0.001
 18.5–24.9 110,236 65.0 63,475 71.5  
 ≥ 25 55,587 32.8 19,045 21.5  
Physical activity (min/day)
 ≥ 60 58,183 34.3 27,453 30.9 <  0.001
 <  60 111,423 65.7 61,308 69.1  
Smoking status
 None 58,054 34.2 65,547 73.8 <  0.001
 Former 31,525 18.6 5884 6.6  
 Current 80,027 47.2 17,330 19.5  
Alcohol intake
 None 48,457 28.6 50,406 56.8 <  0.001
 Sometimes 48,965 28.9 24,558 27.7  
 Everyday 72,184 42.6 13,797 15.5  
Low back pain
 + 3726 2.2 1889 2.1 0.256
 – 165,880 97.8 86,872 97.9  
LDL-C (mg/dL)
 Normal (<  140) 119,824 70.6 63,407 71.4 <  0.001
 High (≥ 140) 49,782 29.4 25,354 28.6  
HDL-C (mg/dL)
 Normal (≥ 40) 154,412 91.0 86,920 97.9 <  0.001
 Low (<  40) 15,194 9.0 1841 2.1  
LDL-C/HDL-C ratio
 Low (<  2.5) 105,067 61.9 70,748 79.7 <  0.001
 High (≥ 2.5) 64,539 38.1 18,013 20.3  
  1. Data are presented as number and percentage, or mean (standard deviation)
  2. LDL-C: Low-density lipoprotein-cholesterol, HDL-C: High-density lipoprotein-cholesterol
  3. a Pearson chi-square test or unpaired t test