#ResearchSpeak & #BrainHealth: age is associated with MS-related disability

The study below proposes including age, instead of disease duration, into a MS severity score. It shows that age is weakly correlated with disability; in StatsSpeak the r-value or correlation coefficient is 0.46. This means that r-squared is 0.21 and means that only 21% of the variance of disability can be explained by age. This weak correlation means that at an individual patient level this age-related score is unlikely to be helpful, but could be useful when studying groups of people. 

This study does tell us, however, that age is a predictor of disability, which is not surprising. We know that as we lose reserve; ‘natural’ ageing will begin to manifest itself on top of MS. In other words MS ages the brain early. This is why we promote brain health and early treatment to protect the brain and delay the onset of age-related cognitive impairment. 

Manouchehrinia et al. Age Related Multiple Sclerosis Severity Score: Disability ranked by age. Mult Scler. 2017 Jan 1:1352458517690618.

BACKGROUND: The Multiple Sclerosis Severity Score (MSSS) is obtained by normalising the Expanded Disability Status Scale (EDSS) score for disease duration and has been a valuable tool in cross-sectional studies.

OBJECTIVE: To assess whether use of age rather than the inherently ambiguous disease duration was a feasible approach.

METHOD: We pooled disability data from three population-based cohorts and developed an Age Related Multiple Sclerosis Severity (ARMSS) score by ranking EDSS scores based on the patient’s age at the time of assessment. We established the power to detect a difference between groups afforded by the ARMSS score and assessed its relative consistency over time.

RESULTS: The study population included 26058 patients from Sweden ( n = 11846), Canada ( n = 6179) and the United Kingdom ( n = 8033). There was a moderate correlation between EDSS and disease duration ( r = 0.46, 95% confidence interval (CI): 0.45-0.47) and between EDSS and age ( r = 0.44, 95% CI: 0.43-0.45). The ARMSS scores showed comparable power to detect disability differences between groups to the updated and original MSSS.

CONCLUSION: Since age is typically unbiased and readily obtained, and the ARMSS and MSSS were comparable, the ARMSS may provide a more versatile tool and could minimise study biases and loss of statistical power caused by inaccurate or missing onset dates.