Illness Perceptions Mediate Back Pain, Quality of Life in Early Axial Spondyloarthritis

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Elevated intensity of back pain was associated with lower health-related quality of life and increased work productivity loss in patients with suspected axial spondyloarthritis.
Elevated intensity of back pain was associated with lower health-related quality of life and increased work productivity loss in patients with suspected axial spondyloarthritis.

In patients with suspected axial spondyloarthritis (axSpA), elevated intensity of back pain was associated with lower health-related quality of life (HRQoL) and increased work productivity loss. These effects were mediated by patient illness perceptions, but not by coping strategies. The results of the study were published in Arthritis Care & Research.

Using Leventhal's Common Sense Model of self-regulation as a theoretical framework for the relationship between pain and health outcomes, investigators examined a variety of cognitive perceptions and coping strategies to determine their effects in this population. Leventhal's Common Sense Model of self-regulation had not been previously studied in relation to axSpA or in those with chronic back pain, and there is sparse information available regarding illness perceptions or coping in patients with early axSpA.

There were 424 patients (64% women; mean age, 30.9 years; mean symptom duration, 13.3 months) analyzed from the prospective Spondyloarthritis Caught Early (SPACE) trial. Using Assessment of Spondyloarthritis international Society (ASAS) criteria, the cohort was categorized into subgroups of participants diagnosed and classified with axSpA (n=145), those only diagnosed with axSpA (n=81), or those diagnosed with chronic back pain (n=198). Intensity of back pain was a determinant, whereas HRQoL and work productivity loss were evaluated outcomes. HRQoL was assessed using the 36-Item Short Form Health Survey (SF-36) physical and mental component summaries.

Regardless of subgroup, regression analyses of all patients showed that adding illness perceptions to the basic model reduced the correlational strength between back pain and physical component summaries (β = −3.5 [r2 = 0.37] to β = −2.7 [r2 = 0.47]), back pain and mental component summaries (β = −0.9 [r2 = 0.03] to β = −0.1 [r2 = 0.32]), and back pain and work productivity loss (β = 7.7 [r2 = 0.36] to β = 6.3 [r2 = 0.40]) while improving explained variance and model performance. However, the addition of coping strategies to the basic and illness perception models did not have the same effect.

For individuals diagnosed and classified with axSpA, inflammation was used as an additional objective indicator of disease activity, replacing back pain intensity, as measured by Spondyloarthritis Research Consortium of Canada scores. In this subset, neither illness perceptions nor coping strategies significantly affected outcomes, and no influence was detected on the strength of associations between pain and HRQoL or work productivity loss.

Study limitations included the cross-sectional nature of the trial, the use of a questionnaire designed for patients with inflammatory rheumatic diseases by those diagnosed with only chronic back pain, and the possibility that r-squares may have been inflated because of the covariance of components of HRQoL and illness perceptions.

Contrary to their initial hypothesis that both illness perception and coping would influence the relationship between back pain and health outcomes, the researchers found that only illness perceptions had a substantial mediating effect. They observed that this is an important finding that demands further investigation to parse these effects in more detail and over time. The authors noted, "Rheumatologists and [healthcare] professionals should be aware that illness perceptions play an important role in determining medical outcomes in these patients," and add that "psychological support could be given in addition to targeting back pain by drug treatment and physiotherapy."

Reference

van Lunteren M, Scharloo M, Ez-Zaitouni Z, et al. The impact of illness perceptions and coping on the association between back pain and health outcomes in patients suspected of axial spondyloarthritis: data from the SPACE cohort [published online April 2, 2018]Arthritis Care Res. doi: 10.1002/acr.23566

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