Reduced Appendicular Lean Body Mass, Muscle Strength, and Size of Type II Muscle Fibers in Patients with Spondyloarthritis versus Healthy Controls: A Cross-Sectional Study
Table 1
Subject characteristics.
Variable
Patients
Controls
p (95% CI lower; upper)
Age (at time of study)
39 ± 4.1 (33–44)
38 ± 5.1 (31–45)
0.57 (−3.7; 6.3)
Body height (cm)
178.1 ± 6.4 (169.5–190.5)
181.8 ± 6.3 (174.5–190.5)
0.04 (−7.3; −0.2)
Femur length
42.4 ± 2.4 (39.5–46.4)
45.4 ± 2.4 (42.5–49.5)
0.002 (−4.7; −1.4)
Femur length/body height (%)
24 ± 1 (23–25)
25 ± 1 (23–27)
0.01 (−0.02; −0.004)
Body mass (kg)
75.2 ± 7.8 (65.0–90.6)
79.9 ± 11.4 (74.2–95.5)
0.04 (−9.0; −0.3)
BMI, kg/m2
23.6 ± 1.3 (21.9–25.6)
24.0 ± 2.3 (20.0–27.8)
0.43 (−1.6; 0.7)
Smoking behavior
0.35
Nonsmoker, (%)
8 (80)
7 (70)
Previous smoker, (%)
1 (10)
3 (30)
Current smoker, (%)
1 (10)
0 (0)
Full-time employment, (%)
10 (100)
10 (100)
1.00
Level of endurance exercise (1–4)
2.3 ± 0.7 (1–3)
2.2 ± 0.6 (1–3)
0.89
Level of strength exercise (1–4)
1.8 ± 0.6 (1–3)
2.0 ± 0.7 (1–3)
0.77
HLA-B27 positive, (%)
9 (90)
—
BASDAI score
2.7 ± 1.1 (0–3.7)
—
BASFI score
0.9 ± 0.8 (0–2.6)
—
BASMI score
2.3 ± 1.1 (0.7–4.6)
—
CRP, mg/L
7.0 ± 7.7 (<1–21)
—
ESR, mm/h
9.3 ± 9.7 (<1–26)
—
Anti-inflammatory medication
NSAIDs, (%)
6 (60)
0 (0)
—
DMARDs, (%)
2 (20)
0 (0)
—
TNF-inhibitors, (%)
4 (40)
0 (0)
—
BMD, g/cm2
1.27 ± 0.04 (1.20–1.33)
1.31 ± 0.13 (1.11–1.60)
0.39 (−0.15; 0.06)
BMD, -score
0.65 ± 0.43 (0–1.3)
1.09 ± 1.33 (−0.9–4.0)
0.37 (−1.5; 0.6)
Lean body mass, kg/m2
18.2 ± 1.8 (15.1–21.3)
18.6 ± 1.6 (17.1–21.6)
0.32 (−1.2; 0.4)
Appendicular lean mass RSMI, kg/m2
8.3 ± 0.9 (7.2–9.6)
8.8 ± 0.8 (8.0–10.1)
0.02 (−0.9; −0.1)
Body fat, %
21.9 ± 7.0 (8.4–30.2)
20.1 ± 6.2 (12.6–31.2)
0.47 (−3.5; 7.1)
Android fat, %
25.3 ± 10.9 (6.3–39.7)
21.6 ± 10.1 (10.6–36.5)
0.31 (−4.1; 11.3)
Gynoid fat, %
21.0 ± 6.9 (8.2–29.6)
20.8 ± 5.7 (15.0–32.8)
0.95 (−5.3; 5.6)
Values are mean ± SD (range) unless otherwise indicated. Comparison between patients and controls tested by paired samples -test unless otherwise indicated. Pearson chi square test. AS: ankylosing spondylitis. BASDAI: Bath AS Disease Activity Index. BASFI: Bath AS Functional Index. BASMI: Bath AS Metrology Index. BMD: bone mineral density. BMI: body mass index. CI: confidence interval. CRP: C-reactive protein. DMARDs: disease modifying antirheumatic drugs. ESR: erythrocyte sedimentation rate. NSAIDs: nonsteroidal anti-inflammatory drugs. PsA: psoriasis arthritis. RSMI: relative skeletal muscle index. SpA: spondyloarthritis. TNF: tumor necrosis factor.
