Table 4 Modifications made to the CHAQ (adapted for achondroplasia)

Instructions

Shortened and simplified wording

To make them easier to understand

Recall period

Change to ‘Over the past 7 days’

The instruction to ‘average’ difficulties experienced ‘over an entire day’ is not applicable to achondroplasia and several participants found the original description of the recall period to be confusing

‘Arising’

Replacement of ‘Arising’ with ‘Getting Up’

‘Getting up’ may better describe the applicable concepts

‘Aids and devices’ items

Capitalization of “…any of the ABOVE activities.”

To draw participants’ attention that only aids/devices used during completion of the associated activities should be considered

Aids and devices (‘hygiene,’ ‘reach,’ ‘gripping and opening things’, ‘errands and chores’)

Addition of ‘step stool’ as a listed aid/device and inclusion of an ‘other’ option

To improve relevance of the measure to achondroplasia and reduce likelihood that participants fail to acknowledge use of a step stool

‘Global evaluation’ item

Removal of ‘Global Evaluation’ heading

To make the item easier to complete

‘Pain’ and ‘global evaluation’ response scales

Replacement of 0–100 VAS with 0–10 NRS

A 0–10 NRS is easier to complete than a 0–100 VAS due to the clear numeric response options, and removes risk of inconsistencies in the length of the VAS scale due to formatting/printing of pen and paper measures

‘Pain’ response scale

Change anchors to ‘No pain’ and ‘Worst pain imaginable’

These anchors are generally considered most appropriate for pain measurement