Table A1.

Intra- and interobserver reliability for grading of individual characteristics.

Intervertebral Disc Weighted Kappa (% agreement)	Reader 1 (intra)		Reader 1 vs. Reader 2		Reader 1 vs. Reader 3		Reader 2 vs. Reader 3
Disc space narrowing (0–3)	0.83	(65)	0.76	(57)	0.80	(63)	0.72	(50)
Osteophytes (0–3)	0.85	(73)	0.76	(65)	0.76	(51)	0.81	(65)
Sclerosis and/or end plate irregularity (0–1)	0.68	(84)	0.56	(79)	0.58	(79)	0.45	(72)
Hip Weighted kappa (% agreement)
Joint space narrowing (0–3)	0.86	(82)	0.65	(64)	0.37	(64)	0.51	(54)
Osteophytes (0–3)	0.75	(80)	0.57	(72)	0.69	(74)	0.59	(70)
Cyst (0–1)	1.00	(100)	1.00	(100)	0.49	(96)	0.49	(96)
Tibiofemoral joint Weighted kappa (% agreement)
Joint space narrowing (0–3)	0.77	(64)	0.63	(52)	0.74	(58)	0.45	(38)
Osteophytes (0–3)	0.90	(78)	0.90	(78)	0.85	(60)	0.86	(68)
Cyst (0–1)	0.81	(94)	0.38	(80)	0.31	(72)	0.44	(76)

Reader 1: Medical doctor and researcher; Reader 2: Radiologist in training with a subspecialization in musculoskeletal radiology; Reader 3: Fellowship-trained musculoskeletal radiologist with five years of experience.