Perceived illness-related uncertainty among patients with mid-stage relapsing-remitting multiple sclerosis

BACKGROUND: Patients with multiple sclerosis (MS) have to deal with a variable disease trajectory often associated with disability and productivity loss. OBJECTIVE: This study aimed to assess illness-related uncertainty and associated correlates in patients with relapsing-remitting multiple sclerosis (RRMS) beyond the near diagnosis phase. METHODS: We conducted a multicenter, non-interventional study including patients diagnosed with RRMS (2017 revised McDonald criteria) and a disease duration of 3 to 8 years. Perceived uncertainty was measured using the Mishel Uncertainty of Illness Scale (MUIS). Associations between the MUIS and different patient-based outcome measures were analyzed using Spearman's rank correlation. RESULTS: A total of 201 patients were studied (mean age (standard deviation): 38.7 (8.4) years, 71.4 % female). The median disease duration (interquartile range) was 6.0 (4.0-7.0) years and the median EDSS score was 1.0 (0.0-2.0). The mean MUIS score was 38.2 (10.8). Perceived uncertainty was positively correlated with fatigue (p < 0.001), symptom severity (p < 0.001), anxiety (p < 0.001), depressive symptoms (p < 0.001), and a threatening illness perception (p < 0.001), and negatively correlated with self-management (p < 0.001), self-efficacy (p < 0.001), processing speed (p < 0.001), knowledge of MS (p = 0.006), and quality of life (p < 0.001). CONCLUSION: Illness-related uncertainty was common in a population of mid-stage RRMS. Identifying uncertainty and its associated factors may be useful for implementing preventive strategies to help patients cope with the disease throughout life.