Visual rating scales for age-related white matter changes (leukoarailosis) - Can the heterogeneity be reduced?

Background and Purpose-It has been hypothesized that the use of different visual rating scales partly explains the discordant results of studies investigating risk factors and clinical correlates of age-related cerebral white matter changes (leukoaraiosis). We aimed to compare 6 widely used rating scales for leukoaraiosis and to calculate conversion coefficients of the score of 1 scale in the score of a second scale. Methods-Two trained raters evaluated 80 pairs of CT and MRI scans using 2 CT and 4 MRI rating scales for white matter changes. Correlations among the scales were evaluated and regression lines were constructed with each of the CT and MRI scale scores as variables. Results-A high correlation was observed in all the paired comparisons of the 6 scales (Spearman's rho ranging from 0.85 to 0.96, P<0.0001). Using regression analysis, we determined numeric parameters to transform the score of 1 scale to the corresponding score for each of the remaining scales and relative confidence intervals. The predictive values of these conversions expressed as R-2 ranged from 0.75 to 0.92. Conclusions-The present findings support the view that a good correlation exists among the considered visual rating scales for white matter changes. With the limitation that conversion parameters are calculated by applying a linear regression to partly nonlinear scales, their use allows comparison of the results of previous studies that used different scales and to pool data from past and ongoing clinical trials.