More efficacious disease-modifying treatment is likely the main reason for a trend to slower progression in relapsing onset multiple sclerosis (ROMS), researchers say.
A Swedish study of more than 7,000 patients with follow-up of about 8.5 years has found those diagnosed in more recent times took longer to reach disability milestones.
It found a 3% reduction per calendar year in patients reaching a sustained Extended Disability Status Score (EDSS) 3.0, a 6% reduction for EDSS 4.0 and a 7% reduction for EDSS 6.0.
“For example, a patient diagnosed in 2010 has 14%, 26%, and 30% lower adjusted risk of EDSS milestones 3.0, 4.0, and 6.0 compared with a patient diagnosed in 2005, respectively,” the study said.
They said the findings were consistent with other evidence including an increasing patient age at the same disability milestones, a reduction in mortality risk over time and a lower cost of care in recent years, despite the higher cost of treatments.
However the study found no similar pattern in patients diagnosed with progressive onset MS (POMS).
The researchers said the increased use of disease-modifying therapies (DMTs) over time was the most likely, but not only, explanation for the observed reduction in disability risk.
“Our finding of a lower risk of progression among ROMS, but not POMS, over time is compatible with availability of DMTs for ROMS but not POMS.”
“Because significant societal resources are presently being invested in MS treatments, our findings, suggesting that these medications may affect the long-term course of disease, are encouraging.”
“However, the supplementary analyses showed similar estimates when adjusting for time with first and second-generation DMTs. We also observed an independent effect of treatment from calendar year on disability milestones, indicating that treatment cannot fully explain the lower risk of reaching disability milestones in recent years.”
The researchers said earlier treatment, other improvements in care, and possible changes in health behaviours or environmental exposures to factors including the Epstein-Barr virus may also be driving the trend to slower progressing disease.