Published research has suggested that socioeconomic disparities are associated with disability in people with MS and with an increasing incidence of MS. “Studies have also shown that a lower socioeconomic status (SES) is associated with higher mortality in the general population, but little is known about this relationship in people with MS,” says Helen Tremlett, PhD, noting that the reasons for this association are likely multifactorial.
For a study published in Multiple Sclerosis Journal, Dr. Tremlett and colleagues investigated the association between SES and mortality risk in people living with MS. Using health administrative data, the researchers identified 12,126 incident MS cases with a first demyelinating event defined as MS onset occurring between 1994 and 2017. A Cox proportional hazard model was used to evaluate associations between SES quintiles (SES-Qs) at MS onset and all-cause mortality.
Most (73%) patients included in the study were women and 26% were previously exposed to disease-modifying therapy (DMT). At the index date, the median age was 44, and 26% of participants had at least one comorbidity.
Lower SES Increases Mortality Risk in MS
Over an average of 10.8years of follow-up, 11% of the study participants died, 58% of whom were women. “We found that a lower SES was associated with higher mortality risk in people with MS,” says Dr. Tremlett.
The study team noted that the findings did not change substantially after adjusting for comorbidities and DMT use. The results were broadly consistent with other recent studies examining mortality risk in people living with MS, which identified SES as an independent risk factor for mortality.
The most deprived people living with MS defined as SES-Q1 had a lower survival rate than the least deprived participants, defined as SES-Q5 (Figure). “For example, people with MS living in the lowest SES quintile areas had a 61% greater mortality risk than those living in the highest SES quintile areas,” Dr. Tremlett says. “Further, the all-cause mortality HRs demonstrated a clear gradient across SES quintile.
Efforts Needed to Foster Improvements in Survival
Findings from the study further demonstrate the importance of SES for people with MS. “Our results show the potential of SES to
impact important clinical outcomes, including mortality risk,” says Dr. Tremlett.
The results also indicate that a complex system of factors may contribute to the association between SES and mortality risk. “Our findings show that efforts to improve economic stability, education, employment, social protection, and the neighborhood or built environments for the most disadvantaged people could improve survival in MS,” Dr. Tremlett notes.
A key strength of the study was that investigators had access to a large population-based cohort of more than 12,000 people with MS, she continues. “We were also able to obtain socioeconomic status close to the time of MS onset,” Dr. Tremlett says. “In addition, we had very little missing information, all of which help reduce selection or recall bias and reverse causation.”
Further research is needed to better understand the influence of socioeconomic disparities on survival in people living with MS.
“While we were able to access neighborhood-level SES, it would be valuable for future studies to assess individual level income and other markers of SES, such as education attainment, occupation, or employment status,” Dr. Tremlett notes. “It will also be important for future research to explore how race/ethnicity and lifestyle factors such as smoking, exercise, or diet might impact survival among patients with MS.”
