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

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

	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
Postmenopausal^a	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 total^b	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 positive^c	73 (55%)		-
Rheumatoid nodules	59 (13%)		9 (13%)
Radiographic changes	137 (31%)		15 (21%)
Hormone levels^d
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)

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).

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