A longitudinal study of symptom botheration in Multiple Sclerosis.

Background: It is well documented that ambulatory disability in MS worsens over time, but there is a dearth of information on symptom evolution in other domains commonly affected by MS. Methods: SymptoMScreen (SyMS) is a validated tool for assessing symptom severity in 12 domains commonly affected by MS. Patients who attended two specialized MS centers filled out SyMS at each visit. We included in the study patients with neurologist-diagnosed MS who completed two SyMS questionnaires separated at least 12 months. We used the first and final assessment and adjusted for time on study, baseline SyMS score, age, sex, race, MS type, disability strata, and site. Changes over time were also examined using Markov chain estimates of moving from one level of botheration to another for each domain over 1-year periods. Results: A total of 1,014 MS patients met the inclusion criteria. Mean composite SyMS score was 1.4 (1.16) at baseline and increased by 0.084 (+/- 0.73) points during 21.0 (+/- 5.5) months of followup (p<0.0001). The initial mean composite SyMS score correlated strongly with the final mean composite SyMS score (r=0.81). Individual domain SyMS scores at baseline were highest for fatigue: 2.2 (+/- 1.7), and lowest for vision: 1.1 (+/- 1.3) and dexterity: 1.1 (+/- 1.4). Small but significant increases during followup were seen in dexterity, bladder, vision, and pain domains, while significant decreases were seen in anxiety and sensory domains. We observed a high degree of inter-individual variability in symptom severity with the more extreme scores tending to resolve over time. Conclusions: Symptom botheration increases modestly year-to-year, as would be expected in a slowly progressive disease that evolves over decades. Initial symptom burden strongly correlated with final symptom burden, but there was a high degree of individual variability in symptom severity.