Geo-epidemiology of autoantibodies in rheumatoid arthritis: comparison between four ethnically diverse populations

Table 1 Cohort characteristics

	Netherlands N = 103	First Nations (Canada) N = 100	Japan N = 174	South-Africa N = 67	p-value
Sex, female	66%	79%	82%	89%¹	0.002
Age, median years (IQR)	58 (49–65)	48 (35–55)	60 (48–67)	49 (41–56)⁷	< 0.001
Disease duration, median years (IQR)	1.3 (1.1–1.8)¹	7.7 (2.5–17.0)	7.5 (4.8–14.8)¹	0 (0.0–0.0)¹	< 0.001
RF positive	90%	93%¹	95%	100%	0.06
Ever smokers	60%⁵	84%	28%⁴	12%	< 0.001
HLA SE present	85%	94%³⁷	78%	71%¹	< 0.001
HLA-DRB1*03 present	14%	5%³⁷	0%	32%¹	< 0.001
Anti-CarP positive	50%	60%	45%	79%	< 0.001
Anti-MAA positive	29%	29%²	22%²	53%¹	< 0.001
Anti-AcVim positive	23%¹	40%⁶	22%³⁰	46%⁶	< 0.001
Treatment at time of sample draw	N data = 72	N data = 72	N data = 174	N data = 67
DMARD-naïve	0 (0%)	6 (8%)	0 (0%)	58 (86%)
Not DMARD-naïve	72 (100%)	66 (92%)	174 (100%)	9 (14%)

Superscripted numbers indicate the number of missing data per characteristic per cohort. Significance is based on Pearson’s chi-square test, t-test, or Kruskal–Wallis test, as appropriate. Disease duration refers to the time in years between the date of 1st presentation and the date of the sample draw. For South Africa, only 9 patients had samples drawn at 6 months and the rest at baseline. Symptom duration refers to the time in years between the date of symptoms and the date of the sample draw. For DMARD use, categories overlap for patients using multiple agents. Other DMARDs include azathioprine, sulfasalazine, hydroxychloroquine, leflunomide, cyclosporine, bucillamine, gold, and minocycline
p-values printed in bold were statistically significant

ISSN: 1478-6362