A much needed metric: Defining reliable and statistically meaningful change of the oral version Symbol Digit Modalities Test (SDMT).

BACKGROUND: The Symbol Digit Modalities Test (SDMT) has been recommended for use in clinical trials and outcome studies to monitor cognitive change. However, defining what is a meaningful change has been elusive for several years. OBJECTIVE: The present investigation aimed to develop methods for assessing individual-level statistically significant change on the SDMT - reliable change indices (RCIs) and standardized regression-based (SRB) equations. METHODS: A total of 219 healthy individuals completed the oral version SDMT at baseline, 6-month and 1-year follow-up. RESULTS: The SDMT demonstrated high reliability across all time points (r's = 0.83 to 0.86). Reliable change scores of 7, 8, and 10 points for the 6-month intervals represented statistically meaningful change at the 0.70, 0.80, and 0.90 confidence intervals, respectively. Over 1-year, a difference of 8, 10, and 12 was statistically meaningful at the 0.70, 0.80, and 0.90 confidence intervals, respectively. SRB equations are also provided taking into account additional factors found to be predictive of SDMT scores over time. CONCLUSION: Clinicians frequently denote a decline of 4 points on the SDMT as meaningful. Results in this large normative sample show that higher cut-points are needed to demonstrate statistically significant decline at the individual level. RCIs are provided for 6 month and one year assessment, which is typical in clinical practice and trials. SRB equations are also provided for use when applicable and may provide a more precise assessment of meaningful change.

Tired of not knowing what that fatigue score means? Normative data of the Modified Fatigue Impact Scale (MFIS).

BACKGROUND: The Modified Fatigue Impact Scale (MFIS) is one of the most common self-report measures used to assess fatigue in multiple sclerosis (MS). Despite its widespread use, there are no existing normative data for the MFIS. OBJECTIVE: The present investigation aimed to develop normative data for the MFIS in a large community sample, stratified by age, gender, and education and to compare the derived new cutoffs to an existing cutoff. METHODS: A total of 675 healthy individuals, stratified by age, gender, and education completed the MFIS. After the removal of 19 outliers, the final sample consisted of 656 individuals. Archival data of 540 individuals with MS who completed the MFIS were also included to analyze the utility of the new cutoffs. RESULTS: There were no main effects on the MFIS for gender. However, there were main effects for age and education. Specifically, younger cohorts (25-34 and 35-44) reported less physical fatigue compared to the two oldest cohorts (55-64 and 65-74). Similar effects were found for total MFIS fatigue with individuals aged 55-64 reporting greater overall fatigue than 35-44 year olds. Finally, 18-24 year olds reported significantly higher levels of cognitive fatigue compared to 35-44 and 65-74 aged cohorts. No other effects were observed for age. Individuals with higher education consistently reported less fatigue. Subsequent analyses also revealed an interaction effect for age x gender. When examining the age x gender interaction, women age 18-24 reported significantly greater levels of physical, cognitive, psychosocial, and total fatigue than their male counterparts. In contrast, men aged 65-74 reported greater physical, cognitive, and total fatigue than women their age. Comparisons of the existing cutoff of the MFIS to the new age, gender, and education specific cutoffs found either comparable or slightly higher rates of fatigue with the latter. CONCLUSION: Based on these findings, updated normative data and age, gender, and education specific cutoffs are provided. Utilization of these updated norms will result in a more accurate assessment of fatigue and will be valuable for those conducting research and/or clinical practice with individual with MS.

A new look at an old test: Normative data of the symbol digit modalities test -Oral version.

BACKGROUND: The Symbol Digit Modalities Tests (SDMT) is the most sensitive measure to multiple sclerosis (MS)-related cognitive dysfunction. However, existing normative data has been under scrutiny. Specifically, they are outdated, do not take into account gender, and are poorly stratified by education. More importantly, there exists no oral only version norms, which is typical administration among individuals with MS. OBJECTIVE: The present investigation aimed to develop updated normative data of the oral version SDMT in which age, gender, and education were taken into consideration. METHODS: A total of 675 healthy individuals, stratified by age, gender, and education completed the oral version SDMT. RESULTS: Significant effects were found for age, gender, and education, consistent with previous contentions. Specifically, performance on the SDMT tends to decline with age, with the most noticeable decline beginning in the third decade of life and continuing into the sixth decade. Women, in general perform better than men, with an average of 5.1 more points. Finally, education effects were apparent among those aged 25-54. CONCLUSION: Based on these findings, updated normative data are provided. Utilization of these updated norms will result in a much needed and more accurate assessment of processing speed for individuals with MS.