What Are Predictors of Mortality in Veterans With MS?

NASHVILLE—Among veterans with multiple sclerosis (MS), excess MS-related mortality is mainly influenced by initial presentation with progressive MS, sensory and cerebellar complaints, and higher levels of disability. Excess mortality also may be influenced by motor complaints and low BMI, according to research presented at the 2018 CMSC Annual Meeting. Main causes of death include MS itself, infection, respiratory disease, and cancer.

These findings suggest a need to pay more attention “to preventive strategies such as yearly influenza immunization, aggressively treating MS-related complications, and comorbidities, especially vascular risk factors,” said the researchers.

Studying mortality in chronic neurologic diseases may help identify treatable risk factors, and population-based studies of English death records have found that about 64% of patients with MS have a neurologic cause of death.

To identify the predictors of mortality in veterans with MS attending outpatient clinics, Meheroz H. Rabadi, MD, Clinical Professor of Neurology at the University of Oklahoma College of Medicine and Medical Director of the Oklahoma City Veterans Affairs Medical Center MS Program, and Christopher E. Aston, PhD, Associate Research Professor of Pediatrics and a biostatistician at the University of Oklahoma Sciences Center, conducted a retrospective study.

Data From a Veterans Affairs Medical Center

The researchers conducted a retrospective electronic chart review of data from 229 veterans with MS diagnosed based on the McDonald criteria who were registered in the MS program at the Oklahoma City Veterans Affairs Medical Center between January 1, 2000, and December 31, 2014. Participants were followed up every four months in the clinic.

Data included age at initial clinic visit, gender, ethnicity and race, age at MS diagnosis, clinical MS subtype (ie, relapsing-remitting, secondary progressive, primary progressive, clinically isolated syndrome, or radiologically isolated syndrome), and initial presenting features (eg, visual complaints, motor weakness, balance disorder, and sensory complaints).

Drs. Rabadi and Aston determined an impairment index based on the presence or absence of motor and nonmotor signs on initial examination. MS severity was measured by initial Expanded Disability Status Scale and total Functional Independence Measure scores.

The researchers recorded the presence of pre-existing and new-onset comorbidities that are commonly encountered in veterans and are the most common causes of disability and death in the United States, such as hypertension, hyperlipidemia, diabetes mellitus, BMI, and history of smoking. They also recorded the presence of MS-related complications such as pressure ulcers, neurogenic bowel, and neurogenic bladder.

Main Causes of Death

A total of 226 participants were included in the analysis; 17% were female. Most participants were white (81%), 13% were black, 1% were Hispanic, and 2% were Native American. The mean age of MS diagnosis was 36, and the mean age of study entry was 49. The mean duration of MS was 21 years, and the mean duration of follow-up was 12 years. In all, 45 (20%) participants had primary progressive MS, 54 (24%) had secondary progressive MS, 96 (43%) had relapsing-remitting MS, and 31 (14%) had another or unknown MS type.

The mortality rate at the end of the 15-year study period was 14%. Among the 33 patients who died, the main causes of death documented were MS disease itself (57% of cases), infection (43%), cancer (18%), and respiratory failure (18%). Cox regression analysis using the whole cohort found that significant predictors of mortality were progressive MS type; older age at entry into the study; the presence of sensory, cerebellar, or motor complaints on presentation; more disability on presentation; lower BMI; diabetes; not having been on disease-modifying therapy; and the presence of pressure ulcers or neurogenic bladder.

Among patients who died during follow up, 36% had primary progressive MS, compared with 17% of patients who were alive; 42% of patients who died had secondary progressive MS, compared with 21% of those who were alive.

In addition, patients who died had an average age of 56 at study entry, compared with an average age of 48 among those who were alive. BMI among those who died was 23.7, compared with 28 among patients who were alive. Thirty-nine percent of patients who died were never on a disease-modifying therapy, compared with 22% of patients who were alive. Thirty-three percent of patients who died had diabetes mellitus, compared with 16% of those who were alive. Finally, 12% of patients who died had pressure ulcers, compared with 2% of patients who were alive, and 82% of patients who died had neurogenic bladder, compared with 53% of patients who were alive.

—Erica Tricarico