WOMAC stiffness subscale

Method

Western Ontario and McMaster Universities Osteoarthritis Index stiffness subscale, 2 items, administered in Likert (0-8) or visual-analogue format.

The method is part of the endpoint identity. Studies measuring the same quantity by a different method are held as separate endpoints.

Notes

The pain (5-item) and physical function (17-item) subscales of the same questionnaire are the near-misses, and the item count is the reason they cannot share a node: with only 2 items this subscale's range and its measurement noise differ sharply from theirs, so a raw point difference here is not comparable to a raw point difference there and a shared 'WOMAC' node would be dominated by the function items. Also distinct from the WOMAC total index, of which this is 2 of 24 items, and from joint stiffness (pooled across scales), which mixes this with morning-stiffness duration in minutes — a duration and an ordinal severity are not the same measurement.