Table 1.

Clinical and pathological characteristics compared between RA, OA and PM controls

Clinical or pathological characteristic	RA	OA	PM
Age, years	68 (60–74)	61 (55–68)	50 (42–69)
Gender, female, %	80	27	55
Serum CRP, mg/l	18 (11–26)‡	<5 (<5–6)	NA
Radiography
JSN (0–6)	4.8 (5–6)	5 (4.8–5.325)	NA
OSTs (0–12)	10 (8–12)	9 (8–10.3)	NA
General morphology
Chondropathy (0–13)	8.5 (5.5–10.3)*	8 (4–10)	4 (3–5)
Subchondral bone thickness, mm	0.12 (0.11–0.17)*	0.17 (0.16–0.21)	0.18 (0.14–0.25)
Subchondral fibrovascular tissue (Y/N), %	90**	55	18
Vascularity
Vascular density, per mm
Non-calcified cartilage	0.45 (0.18–0.83)*	0.42 (0.15–0.82)*	0.09 (0.07–0.19)
Calcified cartilage	0.80 (0.57–0.97)	0.71 (0.68–0.86)	1.2 (0.88–1.8)
Subchondral bone	2.1 (0.6–2.6)**	2.5 (1.6–4.0)*	5.3 (2.7–8.1)
EC proliferation
Vascular channels, %	55*	36	0
Subchondral spaces, %	55	45	11
Inflammatory cells
CD3 subchondral spaces (0–2)	2 (0.8–2)**,†	0.5 (0–1)*	0 (0–0.8)
CD68 subchondral spaces (0–2)	1.5 (0.8–2)	1 (1–2)	1.5 (1–2)
Growth factor expression
VEGF
Subchondral spaces (0–2)	1 (0–2)	0 (0–1)	1 (0–2)
Channels (0–2)	0.5 (0–1)	0.5 (0–1)	1 (0–1)
Chondrocytes, %	27	82*	18
PDGF
Subchondral spaces (0–2)	1 (0–1)	0 (0–1)	0 (0–0)
Channels (0–2)	2 (1–2)**,†	1 (0–1)	0 (0–1)
NGF
Subchondral spaces, %	38	63	33
Channels (proportion positive)	0.50 (0.08–0.69)*	0.54 (0.05–0.79)*	0.14 (0.00–0.43)
Chondrocytes, %	100	75	78

Histological parameters are presented in subchondral bone spaces, vascular channels and (for VEGF and NGF), superficial chondrocytes. Values given as per cent indicate percentage of cases displaying that characteristic. Statistically significant differences between disease groups are highlighted in bold: RA or OA vs PM *P < 0.05, **P < 0.01; RA vs OA †P < 0.05, ^‡P < 0.01. Values are median (IQR) for measurements and scores, or percentage of cases displaying the named characteristic. NA: not available.