Perceived Pain-Related Illness Intrusiveness Among Persons with Multiple Sclerosis

Background: More than half of persons with multiple sclerosis (PwMS) have pain, with nearly a third noting it to be one of their worst symptoms. Pain among PwMS has been associated with poorer psychological functioning and level of productivity. In addition, PwMS report that pain interferes with aspects of their daily functioning. One way of examining the influence of a disease on an individual’s quality of life is through the construct of perceived illness intrusiveness—how the disease and its related treatments disrupt engagement in activities and interests, which contribute to poorer psychological well-being. While the association between other factors (e.g., emotional distress) and perceived illness intrusiveness has been examined in MS, no study to date has investigated pain-related illness intrusiveness in relation to MS symptoms, more generally.

Objectives: To determine the extent to which PwMS experience pain as a particularly intrusive problem among the totality of their experience of MS-related challenges, including their current level of functioning and disability.

Methods: Participants (N = 161) were PwMS with at least mild pain who were recruited through the North American Research Committee on MS (NARCOMS) Registry. Illness intrusiveness was measured using the Illness Intrusiveness Ratings Scale (IIRS). Participants completed the IIRS with regards to their MS, as well as with regards to their pain. Unforced principal component analyses (PCA) with promax rotations were used to evaluate whether the two versions of the IIRS measured similar constructs. A multiple regression analysis was then conducted, with disability (as measured by the Patient Determined Disease Steps) and pain severity as covariates.

Results: Based on the PCA results, 10 items for each version of the IIRS were retained, with good internal consistency (α = 0.87). The MS-related and pain-related IIRS were highly related to each other (ICC = 0.89). Like their overall MS, PwMS viewed their pain as a significant disruptive factor in their daily lives, particularly with their involvement in active recreation, work, health, and community and civic engagement. Even after considering the level of disease severity, pain-related illness intrusiveness was a significant predictor of overall MS-related illness intrusiveness, accounting for 47% of the variance.

Conclusions: These findings highlight the impact that pain has on PwMS’ daily lives, even after accounting for the level of disease severity.