A new study suggests patients whose systolic blood pressure varies significantly over time might be at greater risk of higher multiple sclerosis disability.
Patients with multiple sclerosis (MS) who have significant variability in their systolic blood pressure readings tend to have higher disability levels, according to new research.
The study, published in BMJ Open, took a retrospective look at 92 patients who visited an MS specialty clinic between the years of 2011 and 2015. The patients included in the study had a range of scores on the patient-determined disease steps (PDDS) scale, which measures disability in patients with MS. PDDS scores were measured against visit-to-visit variability in systolic blood pressure (SBP).
Patient SBP variability coefficients were used to divide the group into 3 tertiles, based on how variable their SBP readings were.
Patients in the third tertile (highest variability) were 5.2 times more likely to be in a high disability category of MS, compared to those in the first tertile (lowest variability). Patients in the second tertile were 3.5 times as likely as those in the first tertile to have high MS disability.
“Our results demonstrate a significant and strong graded relationship between SBP variability and self-reported disability outcome measures (PDDS) among MS patients,” concluded corresponding author Myla D. Goldman, MD, of Virginia Commonwealth University.
The precise link between those 2 variables is not fully understood. However, Goldman and colleagues note that SBP variability has already been connected to certain cardiovascular problems. And cardiovascular problems, such as hypertension, have been associated with disability progression in MS. However, the investigators believe this is the first time someone has shown a link between SBP variability itself and MS progression.
Still, the authors note that the relationship does not appear to be a 2-way relationship.
“This cross-sectional study was not designed to make any causal inferences between SBP variability and PDDS scores,” they note. “However, our sensitivity analyses suggest that, while SBP variability was a strong and significant predictor of PDDS scores, the latter did not predict the former.”
The 1-way relationship suggests that SBP variability might be a predictor of future disease progression, which could represent a “vicious cycle” if it turns out that SBP variability leads to worse disease progression, which could then create even more SBP variability.
The authors noted several limitations to the study. For one, the sample size was only 92 patients. For another, it’s possible that additional blood pressure readings were taken by other providers and not included in the electronic medical records to which the investigators had access. The researchers also did not have access to other information that could impact disability, such as disease duration and the use of disease modifying therapies.
However, Goldman and colleagues said there is a sufficient correlation for physicians to keep an eye on the SBP of patients with MS.
“It is still premature to derive any MS-related clinical implications from our results,” they wrote. “But it is advisable that MS patients be checked for SBP variability and those with excessive variability (eg, within-subject [standard deviation] of 8 or higher) be recommended for careful vascular evaluation.”
Doing so might also have a side benefit—identifying patients who have undiagnosed hypertension. Goldman and colleagues said they found that the majority of patients who met the criteria for hypertension using the seventh Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure (JNC 7) and American College of Cardiology/American Heart Association guidelines had not received a hypertension diagnosis.
Goldman MD, Min S, Lobo JM, et alRetrospective cohort study of the relationship between systolic blood pressure variability and multiple sclerosis disability. BMJ Open. 2020;10:e034355. doi: 10.1136/bmjopen-2019-034355.