Knee pain when using stairs early clue to OA

By Lucy Piper, Senior medwireNews Reporter

Feeling knee pain during weight-bearing activities involving knee bending, such as using stairs, could be an early sign of osteoarthritis (OA) and the need for intervention, research indicates.

“Early detection of OA may enable effective interventions before major structural damage has occurred,” comments the team led by Elizabeth Hensor (Chapel Allerton Hospital, Leeds, UK).

They subjected 4674 responses on the Western Ontario McMaster Universities Osteoarthritis (WOMAC) Index to Rasch analysis to determine which question, and therefore which activity, is affirmed first and associated with the onset of pain.

The participants, aged an average of 61 years, either had confirmed OA or were at high risk of OA and they completed the WOMAC Index annually for up to 7 years.

At the point the participants first felt pain (based on a change in total WOMAC score from 0 to above 0), they were asked whether it was felt during certain activities – walking, using stairs, in bed, sitting or lying and standing. When using stairs was the activity most likely to be affirmed followed by when walking.

Of 280 patients who had affirmed just one question, 8% affirmed feeling pain when walking, 76% affirmed pain when using stairs, 7% when in bed, 6% when sitting or lying and 4% when standing.

“Thus question 2 (using stairs) was apparently more likely to be the first affirmed”, notes the team in Arthritis Care and Research.

For Rasch analysis, 25 patients per category were selected at random based on maximum score for score categories 0–17, while 14, 8 and 19 were selected for the higher score categories of 18, 19 and 20, respectively, giving a total subset sample of 491.

The index showed a good overall fit to the Rasch model and very good internal consistency and reliability.

Moreover, it demonstrated that pain on going up or down stairs was the first item to score points, “by a considerable margin,” when the total pain score increased from 0, the researchers report.

The next item was walking, followed by standing, lying or sitting and finally in bed. This order was consistent over subsequent visits.

“Prospective trials will help to determine whether people who develop OA can be identified sooner if pain during such activities is used during screening, perhaps facilitating effective intervention to prevent further progression of the disease”, Hensor and co-workers conclude.

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