Table 2 Fit of "activity-participation" item bank to Rasch model (after rescoring) (n = 266)

WHODAS II – 2.1. In the last 30 days, how much difficulty did you have in standing for long periods such as 30 minutes?

WHODAS II – 2.2. In the last 30 days, how much difficulty did you have in standing up from sitting down?

WHODAS II – 2.3. In the last 30 days, how much difficulty did you have in moving around inside your home?

WHODAS II – 2.4. In the last 30 days, how much difficulty did you have in getting out of your home?

WHODAS II – 2.5. In the last 30 days, how much difficulty did you have in walking a long distance such as a kilometer (or equivalent)?

WHODAS II – 3.1. In the last 30 days, how much difficulty did you have in washing your whole body?

WHODAS II – 3.2. In the last 30 days, how much difficulty did you have in getting dressed?

WHODAS II – 3.3. In the last 30 days, how much difficulty did you have in eating?

WHODAS II – 3.4. In the last 30 days, how much difficulty did you have in staying by yourself for a few days?

WHODAS II – 5.3. In the last 30 days, how much difficulty did you have in doing most important households tasks well?

WHODAS II – 5.4. In the last 30 days, how much difficulty did you have in getting all the household work done that you needed to do?

WHODAS II – 5.5. In the last 30 days, how much difficulty did you have in getting your household work done as quickly as needed?

WHODAS II – 6.1. In the last 30 days, how much of a problem did you have in joining in community activities (for example, festivities, religious or other activities) in the same way as anyone else can

WHODAS II – 6.2. In the last 30 days, how much of a problem did you have because of barriers or hindrances in the world around you?

WHODAS II – 6.8. In the last 30 days, how much of a problem did you have in doing things by yourself for relaxation or pleasure?

ODI 4. Walking

ODI 6. Standing

ODI 9. Social Life

ODI 10. Travelling

RDQ 1. I stay at home most of the time because of my back

RDQ 2. I change position frequently to try to get my back comfortable

RDQ 3. I walk more slowly than usual because of my back

RDQ 4. Because of my back, I am not doing any jobs that I usually do around the house

RDQ 5. Because of my back, I use handrail to get upstairs

RDQ 6. Because of my back, I lie down to rest more often

RDQ 7. Because of my back, I have to hold on to something to get out of an easy chair

RDQ 8. Because of my back, I try to get other people to do things for me

RDQ 9. I get dressed more slowly than usual because of my back

RDQ 10. I only stand up for short periods of time because of my back

RDQ 11. Because of my back, I try not to bend or kneel down

RDQ 12. I find it difficult to get out of chair because of my back

RDQ 14. I find it difficult to turn over in bed because of my back

RDQ 16. I have trouble putting on my sock (or stockings) because of the pain in my back

RDQ 17. I can only walk short distances because of my back pain

RDQ 19. Because of my back pain, I get dressed with the help of someone else

RDQ 21. I avoid heavy jobs around the house because of my back

RDQ 23. Because of my back, I go upstairs more slowly than usual

RDQ 24. I stay in bed most of the time because of my back

NHP 8. I find it painful to change position

NHP 11. I find it hard to bend

NHP 12. Everything is an effort

NHP 18. I find it hard to reach for things

NHP 19. I'm in pain when I walk

NHP 24. I'm in pain when I'm standing

NHP 25. I find it hard to get dressed by myself

NHP 26. I soon run out of energy

NHP 27. I find it hard to stand for long (e.g., at the kitchen sink, waiting in a line)

NHP 36. I'm in pain when going up or down stairs

NHP 38. I'm in pain when I'm sitting