The Influence of Sex on Patients with Rheumatoid Arthritis in a Large Observational Cohort

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Figure 1.
The relation between HealthAssessment Questionnaire (HAQ) results and disease duration. Fitted lines were adjusted by age and medications using mean values for each sex.

Table 1.

Baseline patient characteristics and sex differences.

Variable	Male, median (IQR)	Female, median (IQR)	Mean Difference (95% CI)	p
Age (years)	62 (54–70)	59 (50–67)	−2.79 (–3.76– –1.81)	2.13 × 10⁻⁹ ^†^*
Duration, yrs	8 (4–14)	10 (5–16)	1.55 (0.87–2.22)	4.77 × 10⁻⁶ ^†^*
DAS28	2.94 (2.11–3.89)	3.45 (2.67–4.30)	0.50 (0.41–0.59)	9.06 × 10⁻²⁴ ^†^*
DAS28-CRP	2.59 (1.90–3.39)	2.76 (2.02–3.59)	0.17 (0.08–0.25)	2.10 × 10⁻⁴ ^†^*
HAQ	0.25 (0–0.875)	0.63 (0.13–1.38)	0.33 (0.27–0.39)	1.04 × 10⁻³³ ^†^*
TJC45	1 (0–2)	1 (0–3)	0.75 (0.39–1.10)	8.00 × 10⁻⁸ ^†^*
SJC45	1 (0–2)	1 (0–3)	0.61 (0.35–0.87)	3.49 × 10⁻⁹ ^†^*
Patient pain VAS	18 (5–43)	23 (8–51)	4.49 (2.49–6.49)	2.89 × 10⁻⁶ ^†^*
Patient global VAS	21 (7–48.5)	25 (9–52)	3.91 (1.98–5.85)	3.62 × 10⁻⁵ ^†^*
Physician global VAS	9 (2–19)	10 (3–23)	1.99 (0.81–3.17)	4.22 × 10⁻⁴ ^†^*
CRP, mg/dl	0.5 (0.2–1.3)	0.5 (0.2–1.2)	−0.1 (–0.21–0.02)	0.02^†
ESR, mm/h	17.9 (8.7–34.8)	27.6 (16.1–45)	7.37 (5.67–9.07)	3.34 × 10⁻²⁹ ^†^*
RF, IU/ml	70.5 (16–215)	59 (19–148)	−41.27 (–62.73– –19.82)	0.13^†
MTX dose, mg/wk	6 (4–8)	6 (4–8)	−0.12 (–0.36–0.12)	0.19^†
PSL dose, mg/day	5 (3–6)	4 (3–5)	−0.52 (–0.72– –0.31)	3.2 × 10⁻³ ^†^*
DMARD, mean use	88.1%	90.2%		0.07^††
MTX, mean use	49.4%	56.1%		5.94 × 10⁻⁴ ^††^*
PSL, mean use	51.3%	53.7%		0.23^††

IQR: interquartile range; DMARD: disease modifying antirheumatic drug; MTX: methotrexate; PSL: prednisolone; DAS: Disease Activity Score; CRP: C-reactive protein; HAQ: Health Assessment Questionnaire; TJC: tender joint count; SJC: swollen joint count; VAS: visual analog scale; ESR: erythrocyte sedimentation rate; RF: rheumatoid factor.
↵† Mann-Whitney U-test;
↵†† Fisher exact test.
↵* Statistical significance (p < 0.01).

Table 2.

Adjusted sex difference variables and their contributions to the differences in the 2 groups.

Variable	Relation Coefficient	OR	SE	Confidence Interval	p	% Contribution
HAQ	0.992	2.697	0.085	2.284, 3.183	1.06 × 10⁻³¹	36.36
BMI	−0.117	0.890	0.014	0.866, 0.915	8.63 × 10⁻¹⁷	26.34
Age	−0.026	0.974	0.004	0.967, 0.981	3.42 × 10⁻¹²	12.83
CRP	−0.132	0.877	0.029	0.828, 0.927	4.85 × 10⁻⁶	7.51
PSL dose	−0.056	0.946	0.014	0.920, 0.972	5.57 × 10⁻⁵	4.94
RF	−0.001	0.999	0.000	0.999, 1.000	1.20 × 10⁻⁴	3.49
Patient global VAS	−0.007	0.993	0.002	0.989, 0.997	3.30 × 10⁻⁴	3.00
SJC	0.054	1.056	0.017	1.021, 1.092	1.52 × 10⁻³	3.55
Disease duration	0.014	1.014	0.005	1.003, 1.024	0.01	1.97

SE: standard error; HAQ: Health Assessment Questionnaire; BMI: body mass index; CRP: C-reactive protein; PSL: prednisolone; RF: rheumatoid factor; VAS: visual analog scale; SJC: swollen joint count.