Multiple Sclerosis Symptom Onset May Affect Disability Progression

New findings suggest that individuals with late-onset multiple sclerosis tend to have rapidly increasing disability scores compared with younger patients.

In most patients, initial symptoms of multiple sclerosis develop between 18- and 40-years-old, with only 20% of patients experiencing the symptoms for the first time after age 40. However, the occurrence of late-onset multiple sclerosis seems to be increasingly more common.

Late-onset of the disease can be challenging to both physicians and patients since it presents differently, and also has a different disease course compared with earlier onset disease. There have been relatively few studies that have explored the progression of late-onset disease.

In a study published by Plos One, researchers collected demographic and clinical data about patients with multiple sclerosis living in Kuwait. They used the Kuwait National MS Registry to gather information about presentation at onset, duration, amount of relapses, and expanded disability status scale (EDSS) scores.

Researchers focused on the time from baseline to sustained disability. They defined sustained disability as an EDSS score of 6.0, which has been indirectly linked to disability progression.

This disease score means that the individual must use an assistance device, such as a cane or a crutch, intermittently or unilaterally to walk 100 meters with or without resting, according to the study.

Included in the study were 99 patients with late-onset disease, and 804 patients with early-onset multiple sclerosis. The median age in the late-onset group was 45.9, and the median age of patients in the early-onset group was 26.6.

During the follow-up period, an analysis of EDSS scores showed that 19.2% of late-onset patients, and 15.7 of early-onset patients reached a score of 6.0. Researchers discovered that late-onset patients reached this level of disability in an average of 6.5 years, while early-onset patients reached it in 12.8 years.

This difference shows a 3.6-increased likelihood in late-onset patients reaching an EDSS score of 6.0 compared with patients with early-onset multiple sclerosis, according to the study. Being male (1.85) and having a presentation of spinal symptoms at onset (1.47) were also linked to an increased risk of reaching an EDSS score of 6.0 during a short period of time.

Symptoms of spinal cord disease at onset of multiple sclerosis were more prevalent among late-onset patients (46.5%) compared with early-onset patients (32.3%).

The researchers also discovered that 26.3% of late-onset patients progressed to secondary progressive multiple sclerosis, a more severe disease state, compared with only 17.8% of early-onset patients who progressed.

“LOMS [late-onset multiple sclerosis] patients attained EDSS 6.0 in a significantly shorter period that was influenced by male gender and spinal cord presentation at MS onset,” the study concluded. “Since the prevalence of LOMS will continue to increase, there is a need to better understand the natural history of these patients and their response to earlier institution of treatment.”