Hypertension Triples Disability Risk in Hispanic/Latino MS Patients
Hypertension — high blood pressure — triples the risk of severe walking disability in Hispanic and Latino people with multiple sclerosis (MS), a new observational study reports.
The study, “Hypertension and hypertension severity in Hispanics/Latinx with MS,” was published in the Multiple Sclerosis Journal.
Although the cause of MS is unknown, genetic and environmental factors are known to contribute to its development.
Research has established that underlying cardiovascular conditions such as hypertension are associated with an increase in MS diagnosis delay, disability progression, hospitalization, and brain atrophy (shrinkage).
Hypertension occurs when the force of blood flowing through blood vessels is consistently too high. The condition occurs more frequently in Hispanics/Latinos than Caucasians in the United States. Moreover, Hispanics/Latinos with MS experience a more rapid disease progression, with
a higher risk of mortality and morbidity than Caucasians. However, it is not known whether underlying hypertension contributes to a worse MS prognosis in Hispanics/Latinos.
A team of researchers in the U.S. now has sought to investigate if a link exists between hypertension and severe disease in Hispanic/Latino people with MS.
A total of 451 Hispanic/Latino people with MS enrolled at the University of Southern California from November 2007 to April 2019 were included. Participants had a mean age of 38.8 years, 63% were female, 92.6% had relapsing MS, and the mean disease duration for the group was 8.7 years.
In total, 41.9% of the group had medical comorbidities (co-existing ailments), with almost a quarter (24.2%) having a vascular comorbidity, including hypertension, diabetes, hyperlipidemia (abnormally high levels of fats in the blood), ischemic events (when blood flow and oxygen are restricted or reduced in a part of the body), and smoking.
Based on American Heart Association (AHA) definitions, blood pressure is categorized into five groups according to its increased severity: normal; elevated; stage 1 hypertension; stage 2 hypertension; and hypertensive crisis. In the group analyzed, hypertension affected 7.3% of participants, with 22% of these classified as stage 1 hypertension and 9.8% as stage 2. Hypertension was more common among participants age 40 or older.
Severe disability was present in 27% of participants. Those with any vascular comorbidity, including smoking, had a more than 1.5 times higher risk of having severe ambulatory (walking) disability. Notably, hypertension alone increased the risk of having severe disability by three times.
The risk of severe disability increased as hypertension worsened, as people with stage 2 hypertension exhibited significantly higher disability risk than those with stage 1 hypertension, elevated, or normal blood pressure.
“In contrast to the previous White cohorts which found associations with multiple cardiovascular comorbidities (underlying cardiovascular conditions), only hypertension was independently associated with disability in our cohort, indicating that relationship with cardiovascular comorbidities and disability is mostly driven by hypertension in this [Hispanic/Latino] population,” the researchers wrote.
Interestingly, blood pressure measurements based on AHA criteria revealed that 27.5% of the group analyzed had hypertension, but only 7.3% had an established diagnosis, indicating that hypertension is under-diagnosed.
According to the team, this finding was not surprising because uncontrolled hypertension is common among Hispanic/Latino people. Moreover, they often have poor accessibility to treatments specific for hypertension and MS, possibly contributing to the high incidence rates of hypertension.
“While we do not fully understand whether the observed variance in disease severity is due to [hypertension] or other factors associated with MS, race/ethnicity remains an important surrogate for other risk factors that could be involved in disease progression,” the researchers wrote.
The team noted some limitations of the study, including its retrospective (past events) design, the possibility of selection bias, and excluding other unmeasured variables that may have affected the results.
Nonetheless, the data obtained suggested that Hispanic/Latino people “with MS and a diagnosis of [hypertension], particularly stage II [hypertension], are three times more likely to have severe ambulatory disability compared to those without [hypertension],” they wrote.
Future studies need to “evaluate whether [hypertension] is associated with disease progression and whether disparities in [hypertension] help explain disparities in disability for [Hispanics/Latinos] with MS compared to Whites,” the team concluded.
This study was supported by the National MS Society.