Characteristics Associated with Sustained Disease Progression in Previously Relapsing MS Patients

Background: The emerging definition of secondary progressive multiple sclerosis (SPMS) is based on the concept that MS is a continuously destructive disease in which progressive disability ensues once a threshold is reached. Long-term disease management requires a better understanding timing of the gradual transition from the relapsing-remitting to the predominantly progressive phase.

 

Objectives: Describe characteristics of persons with relapsing MS who reach Patient Determined Disease Steps (PDDS) score of 4 (Early Cane Use) or higher over a 5-year follow-up period.

 

Methods: We included NARCOMS registry participants who had completed at least one semi-annual update survey in each of the 5 years in 2006-2010 and were US residents with diagnosis of MS and a history of relapse(s). Participants were classified into low disability (LD; PDDS < 3) or high disability (HD; PDDS > 4) groups based on their last PDDS score in 2010. Socio-demographics, MS history and disability levels are reported using proportions and median values. Statistical comparisons were made with chi-square or Wilcoxon tests, as applicable; p-values <0.05 considered meaningful.

 

Results: Of 5,452 eligible participants, 55.6% reported HD in 2010, 44.4% reported LD. Those with HD were more likely to be male (27.3% HD vs. 16.9% LD, p<0.0001), older at diagnosis (39 yrs. HD vs. 38 yrs. LD, p=0.004) and at enrollment in NARCOMS (55 HD vs. 49 LD, p<0.0001), with a longer duration of MS at the start of follow-up (15 yrs. HD vs. 9 yrs. LD, p<0.0001). A lower proportion HD reported relapse in the 6 months before enrollment (14.1% HD vs. 27.9% LD, p<0.0001). Retrospectively, those with HD in 2010 had a higher median PDDS score at enrollment in NARCOMS (4 HD vs. 1 LD, p<0.0001), at start of follow-up (5 HD vs. 1 LD, p<0.0001), and by definition at end of follow-up (6 HD vs. 1 HD, p<0.0001), and a greater PDDS worsening between 2006 and 2010 (mean worsening 0.6 points for HD vs. no change for LD, p<0.0001). Those with HD also reported greater worsening in the mobility, hand, vision, and bladder/bowel Performance Scales (p<0.0001).

Conclusions: While participants with high disability in 2010 began follow-up in 2006 with a higher level of disability, they also experienced more worsening over the follow-up period compared to those with lower disability. This conclusion assumes a linear increase of the PDDS scale over the follow up period, therefore a more detailed longitudinal analyses will also be presented.

Acknowledgements: NARCOMS is supported in part by the CMSC and the Foundation of the CMSC.  This study was supported by Novartis Pharmaceuticals.