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.
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.