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Table 1 Characteristics of rheumatoid arthritis cases and matched controls in the NHS and WHS

From: A prospective study of androgen levels, hormone-related genes and risk of rheumatoid arthritis

  NHS
(449 cases/449 controls)
WHS
(72 cases/202 controls)
  RA cases Controls RA cases Controls
Matching factors     
   Age at blood draw 55 ± 8 55 ± 8 55 ± 8 55 ± 8
   Postmenopausala 179 (67%) 179 (67%) 39 (54%) 109 (54%)
   Current postmenopausal hormone use 92 (34%) 93 (35%) 37 (51%) 104 (51%)
Other characteristics     
   Ever cigarette smokers 272 (61%) 252 (56%) 46 (64%) 106 (52%)
   Pack-years among smokers 23 ± 16 23 ± 20 - -
   Parous 411 (92%) 420 (94%) 62 (86%) 180 (89%)
   Breastfed babies ≥ 12 months totalb 67 (15%) 81 (18%) - -
   Age at menarche <12 years 107 (24%) 96 (22%) 18 (25%) 47 (23%)
   Irregular menstrual cycles 66 (15%) 61 (14%) - -
   Body mass index (kg/m2) 26 ± 5 26 ± 5 26 ± 6 26 ± 5
Rheumatoid arthritis characteristics     
   Age at diagnosis 55 ± 10   61 ± 8  
   Rheumatoid factor positive 260 (58%)   42 (58%)  
   Cyclic citrullinated antibody positivec 73 (55%)   -  
   Rheumatoid nodules 59 (13%)   9 (13%)  
   Radiographic changes 137 (31%)   15 (21%)  
Hormone levelsd     
   Free testosterone (pg/ml) 0.06 (0.03) 0.06 (0.03)   
   Free testosterone (pg/ml) 0.06 (0.05 to 0.08) 0.06 (0.04 to 0.08)   
   Total testosterone (pg/ml) 22.0 ± 10.0 21.7 ± 11.1   
   Total testosterone (pg/ml) 22.0 (16.0 to 31.0) 21.0 (16.0 to 29.0)   
   DHEAS (pg/ml) 91.1 ± 68.9 87.5 ± 59.0   
   DHEAS (pg/ml) 72.1 (38.5 to 113.9) 69.0 (46.0 to 116.4)   
  1. Data presented as mean ± standard deviation, n (%) or median (25th to 75th percentile). aPercentage is calculated among postmenopausal women or parous women, with unknown/missing group excluded. For the rest of the variables, percentage was calculated with missing category included. bCalculated among parous women in the Nurses' Health Study (NHS), data not available in the Women's Health Study (WHS). cCyclic citrullinated peptide antibodies tested in 132 preclinical rheumatoid arthritis (RA) samples. dMeasured in NHS samples for free and total testosterone and dehydroepiandrosterone sulfate (DHEAS) (n = 132 rheumatoid arthritis cases, n = 396 controls).