Table 4

Correlation of each item and total Intermittent and Constant Osteoarthritis and Pain scores (n=110)

ICOAP items	Corrected item-total coefficients*	Corrected item-total coefficients†	Cronbach’s α if item deleted*	Cronbach’s α if item deleted†
Constant pain subscale
1. In the past week, how intense has your constant knee pain been?	0.853	0.802	0.913	0.941
2. In the past week, how much has your constant knee pain affected your sleep?	0.697	0.698	0.940	0.945
3. In the past week, how much has your constant knee pain affected your overall quality of life?	0.869	0.833	0.910	0.940
4. In the past week, how frustrated or annoyed have you been by your constant knee pain?	0.855	0.847	0.912	0.940
5. In the past week, how upset or worried have you been by your constant knee pain?	0.852	0.850	0.914	0.940
Intermittent pain subscale
6. In the past week, how intense has your most severe knee pain that comes and goes been?	0.716	0.728	0.887	0.944
7. In the past week, how frequent has this knee pain that comes and goes occurred?	0.620	0.623	0.900	0.948
8. In the past week, how much has your knee pain that comes and goes affected your sleep?	0.680	0.739	0.892	0.944
9. In the past week, how much has your knee pain that comes and goes affected your overall quality of life?	0.841	0.803	0.869	0.942
10. In the past week, how frustrated or annoyed have you been by your knee pain that comes and goes?	0.787	0.794	0.876	0.942
11. In the past week, how upset or worried have you been by your knee pain that comes and goes?	0.755	0.711	0.882	0.945