To identify disease and patient characteristics used to diagnose secondary progressive (SPMS). We hypothesized that evidence of progression independent of relapse activity (PIRA) would be the most relied upon factor, along with other markers of neurodegeneration/progression.

Influential disability-related metrics for identifying SPMS were PIRA (78% by self-report vs. 55% of chart audit submissions), accumulation of disability/lack of improvement between relapses (54% vs 39%), decreasing walking speed (45% vs. 17%), and worsening 6-month Expanded Disability Status Scale (EDSS) score (40% vs. 16%). While most disability measures were consistent between self-report and audit, decline in activities of daily living (61% vs. 18%) and increasing brain atrophy (42% vs. 9%) were more influential in theory, as compared to clinical practice. Disease activity metrics were also influential including: increasing lesion burden (61% self-report, 36% chart audit) and increasing relapse rate (28% vs. 14%). Absence of relapses (48% vs. 24%) was an influential factor, and, to a lesser degree, decreasing relapses (22% vs. 11%). Age did not appear to be a major influential factor (12% vs. 8%).