Table 4.

The interclass correlation coefficient (ICC) for questions of the Persian OKS

	Mean (SD)	Floor effect (%)	Ceiling effect (%)	ICC
1. How would you describe the pain you usually have in your knee?	3.2 (0.82)	1.2%	56.2%	0.91
2. Have you had any trouble washing and drying yourself (all over) because of your knee?	1.61 (1.25)	30%	1.2%
3. Have you had any trouble getting in and out of the car or using public transport because of your knee? (With or without a stick)	2.08 (1.11)	13.8%	3.8%
4. For how long are you able to walk before the pain in your knee becomes severe? (With or without a stick)	2.06 (1.31)	17.5%	13.8%
5. After a meal (sat at a table), how painful has it been for you to stand up from a chair because of your knee?	2.11 (1.12)	8.8%	7.5%
6. Have you been limping when walking, because of your knee?	2.11 (1.46)	17.5%	26.2%
7. Could you kneel down and get up again afterwards?	3.22 (1.14)	6.2%	56.2%
8. Are you troubled by pain in your knee at night in bed?	2.64 (1.23)	10%	32.5%
9. How much has pain from your knee interfered with your usual work? (including housework)	2.72 (1.14)	6.2%	26.2%
10. Have you felt that your knee might suddenly give away or let you down?	1.22 (1.21)	35%	3.8%
11. Could you do household shopping on your own?	2.18 (1.48)	21.2%	22.5%
12. Could you walk down a flight of stairs?	2.10 (1.10)	10%	5%
Total	20.4 (9.8)	1.2%	1.2%