, new research suggests. Analysis from the phase 3 ASCEND trial of nearly 900 patients showed that MRI measures were not associated with worsening of scores on the Expanded Disability Status Scale (EDSS), the most widely used physical outcome measure.
The few associations that were shown between MRI measures and clinical outcomes “were with the newer and possibly more sensitive outcomes” – the Timed 25-Foot Walk (T25FW) and Nine-Hole Peg Test (NHPT), wrote the investigators, led by Marcus W. Koch, MD, PhD, associate professor of neurology in the MS program at the University of Calgary, Canada.
However, “it is unclear if these associations are clinically meaningful,” they added.
Worsening on the NHPT at 48 weeks was associated with a 0.86% loss in normalized brain volume; worsening at 96 weeks was associated with a 1.47% loss.
The findings were published online July 26 in the Multiple Sclerosis Journal.
ASCEND data analysis
Although brain volume loss occurs in all forms of MS, it is believed to be particularly relevant in SPMS. Clinical trials often use MRI measures of brain volume as endpoints, likely on the assumption that these measures indicate worsening disability.
However, brain volume loss proceeds slowly. Changes that occur during the typical 2-year study period may not be associated with significant physical or cognitive disability.
In the current study, investigators examined data from the ASCEND trial, which assessed the use of natalizumab for patients with SPMS, to examine these potential associations. Eligible participants in ASCEND were between ages 18 and 58 years, had had SPMS for 2 or more years, had had disability progression during the previous year, and had an EDSS score between 3.0 and 6.5 at baseline.
Participants underwent gadolinium-enhanced cranial MRI at screening and at 24, 48, 72, and 96 weeks. MRI outcomes included normalized brain volume, normalized cortical gray matter volume, and normalized whole gray matter volume. The ASCEND investigators also examined the number and volume of T2 and contrast-enhancing lesions.
The study’s clinical outcomes included scores on the EDSS, T25FW, and NHPT, which were administered at baseline and every 12 weeks thereafter. Participants also underwent the Symbol Digit Modalities Test (SDMT), which is a cognitive assessment, at baseline and every 4 weeks thereafter. In addition, 3-month confirmed disability progression was measured every 12 weeks.
Few significant associations
The investigators’ analysis included 889 patients (61.9% women; median age, 48 years). The median EDSS score at screening was 6.
Brain volume measures decreased consistently during follow-up. Mean volume loss at 96 weeks was about 1%. In contrast, T2 lesion volume changed little during follow-up. The cumulative number of contrast-enhancing lesions and the cumulative number of new or newly enlarging T2 lesions increased steadily during follow-up.
For an increasing number of participants, scores on the EDSS, NHPT, and T25FW worsened significantly during follow-up. Performance on SDMT, however, changed little. Of all the clinical measures, the NHPT was most consistently associated with MRI measures.
Among patients whose NHPT score worsened at 48 weeks, there was greater loss of normalized brain volume (0.86%, P = .02), normalized cortical gray matter volume (1.15%, P = .03), and normalized whole gray matter volume (1.08%, P = .03) than among those whose NHPT score did not worsen.
Among patients whose NHPT score worsened at 96 weeks, there was greater normalized brain volume loss (1.47%, P = .002), greater increase in T2 lesion volume (4.68%, P = .02), and a greater number of cumulative new or newly enlarging T2 lesions (7.81, P = .03) than those whose NHPT score did not worsen.
After adjusting the data for covariables, the investigators found few significant associations between MRI measures and clinical outcomes. Worsening on the EDSS and SDMT was not associated with any MRI outcome.