People with multiple sclerosis (MS) with a rapid decline in walking abilities were more likely to be older when first examined, female, or Black, according to a large data study in the U.S.
Other factors associated with worsening walking impairment over time included living with MS longer, having progressive disease, more severe depressive symptoms, relying on public health insurance, and living in a location with a lower socioeconomic status.
These findings highlight that socially disadvantaged and economically marginalized MS patients in the U.S. are the most vulnerable to declines in walking abilities, the researchers said.
The study, “Long-term trajectories of ambulatory impairment in multiple sclerosis,” was published in the Multiple Sclerosis Journal.
MS walking difficulties common as the disease progresses
MS is marked by an autoimmune response targeting the brain and spinal cord. It can present a wide range of disease symptoms that vary from person to person, depending on which parts of the nervous system are affected.
A large majority of MS patients experience changes in normal walking patterns, or ambulatory dysfunction, with about 90% considerably affected 10 years after symptom onset.
The timed 25-foot walk (T25-FW), a test that measures how long it takes to walk 25 feet, is a common objective measure of walking speed in MS and is routinely used in clinical practice and research to assess ambulatory function.
Researchers based at Case Western Reserve University, in Ohio, analyzed T25-FW measures collected from 7,683 people with MS. Their goal was to identify distinct subgroups with different changes in walking abilities over time.
Disease duration was a mean of 10 years, and 73% of the population was female, with 85% identifying as white and 12% as Black. Among them, 72% were diagnosed with relapsing forms of MS, and 20% had either primary progressive MS or secondary progressive MS.
Six classes of walking impairment were identified based on T25-FW patterns. Class 1 included those with very minimal but worsening impairment (7.2% of patients), class 2 had minimal impairment (22.3%), and class 3 indicated mild impairment (26.4%). Class 4 denoted moderate impairment (19.1%), class 5 high impairment (15.1%), and class 6 represented very high impairment (9.9%).
Blacks at first visit were 4% of least affected group, 20% of those most affected
Age at baseline, or the first visit to the clinic for MS, and disease duration increased with worsening impairment across subgroups. For example, the mean age at baseline was 38 years in class 1 compared with 53.5 in class 6. Likewise, the disease duration in class 1 was a mean of 5.8 years, while it was 15.5 years in class 6.
Several other factors also changed with class assignment. For example, Black MS patients comprised 4% of class 1 and 20% of class 6 at baseline. Women, likewise, were 56% class 1’s population, and 71% to 76% of all other subgroups with greater walking difficulties.
Overall, assignment to a subgroup by increasing degrees of impairment were independently and significantly associated with various factors.
Such factors included older age, being female, being Black, living with MS longer, having progressive disease, experiencing depressive symptoms, smoking (current or in past), being divorced, insurance via Medicaid/Medicare, and residing in an area with a lower socioeconomic status.
Three attributes “were the strongest predictors of membership to the most impaired trajectories,” the researchers wrote. They were to “have progressive disease, be Black (vs White), and be Medicaid/Medicare beneficiaries.”
Depressive symptoms also seen to factor in a decline in walking abilities
A separate analysis focusing on 2,591 individuals diagnosed with MS five or fewer years ago found similarities with the entire study group.
This analysis identified eight classes, from class 1 with very minimal impairment with eventual worsening to very stable high impairment in class 8. While class 3 started with minimal impairment and class 6 with moderate impairment, both rapidly converged with very high impairment subgroups over time.
Here, those with rapid progression were more likely to be Black, have high blood pressure, more depressive symptoms, and live in an area considered “deprived” by socioeconomic status. Classes 3 and 6 also had a higher number of current smokers.
“Black patients comprised 5% of Class 1 and 26% of Class 8,” the researchers noted. Likewise, “11.6% of Black patients and 29.3% of White patients were in Classes 1 and 2 compared to 27.4% of Black patients and 11.7% of White patients in Classes 7 and 8.”
Early stage MS patients with a decline in walking abilities (classes 6-8) were similar regarding marital status, insurance overage, depressive symptom severity, and socioeconomic status.
“We identified novel subgroups of MS patients with distinct long-term ambulatory impairment trajectories,” the researchers concluded.
“These results underscore that socially disadvantaged and economically marginalized MS patients are the most vulnerable for more severe ambulatory impairment, and are therefore the patients who may benefit most from health promotion and tailored care plans,” they added.
