"Where Does It Hurt Most?" Is a Valid Diagnostic Question

White SG, McNair P, Laslett M, Hing W. Do patients undergoing physical testing report pain intensity reliably?Arthritis Care & Research. 2014. Accepted article. doi: 10.1002/acr.22530.

Thom N, Ritchlin CT, Zhang X, Reveille J, Michael H. Weisman MH. Prevalence of chronic axial pain, inflammatory back pain and spondyloarthritis in diagnosed psoriasis.Arthritis Care & Research. 2014 Accepted article. doi: 10.1002/acr.22528.

Two new studies say that patients' descriptions of back or hip pain may have clinically valid utiliy in diagnosis of their conditions.

A small study involvimg patients with hip pain in New Zealand found numerical pain rating scale (NPRS) scores from more than a dozen standardized tests, such as external hip rotation, and found those scores to be “almost perfect” in their reliability.

In a separate study, data from more than 5,000 people in the US National Health and Nutrition Examination Survey (NHANES) showed those with a prior diagnosis of psoriasis who report lower back and alternating buttock pain are almost 14 times more likely to have spondyloarthritis (SpA) than those without psoriasis. The authors suggest screening patients with sudden-onset axial or alternating buttock pain for SpA and inflammatory back pain.

In the New Zealand study, a single examiner performed standardized physical tests among 18 people, repeating them 1 hour and then 2 to 7 days later. “Patients demonstrated ‘substantial’ or ‘almost perfect’ reliability in reporting pain intensity with 11 of 14 tests,” the authors state.

The Standard Error of Measurements (SEM) values were nearly identical within and between sessions. An average SEM value of 0.9 points should be considered when precise calculations of changes in pain intensity are important, the researchers comment.

The authors of the NHANES study found a significantly higherprevalence of SpA  in the psoriasis group than in the non-psoriasis group (14.3% vs 1.5%) over a 3-month period, using the Amor or European Spondylarthropathy Study Group (ESSG) SpA criteria .

Sudden onset of axial pain within 1 hour to a day was higher among those with psoriasis than those without (23.3% vs 13%).

One limitation of this study: Providers' diagnoses of psoriasis could not be validated formally.