Impact of Cognitive Impairment on Quality of Life and Work Productivity of Relapsing-Remitting Multiple Sclerosis Patients: A Systematic Literature Review

Background: In 2020, there were an estimated 2.8 million people living with multiple sclerosis (MS) worldwide, with relapsing-remitting MS (RRMS) accounting for 85% of those. Cognitive impairment (CI), affecting 40-65% of MS patients, may have a significant impact on patient quality of life (QoL).

Objectives: The aim of this systematic literature review was to summarize the impact of CI on the QoL and work productivity in RRMS patients.

Methods: A systematic search was performed in EMBASE, MEDLINE and MEDLINE-IN-PROCESS on July 27^th, 2020. Abstracts published between 2017 and 2020 were also captured. Correlations between CI and QoL and work productivity were assessed based on variables meeting a ±0.3 correlation threshold.

Results: Out of 5216 screened publications, 28 were included in the review. Studies were predominantly prospective cross-sectional (n=11, 40%) and conducted in multiple countries. CI and its correlation with QoL was assessed in 25 studies, and work productivity was assessed in 5 studies. The sample size ranged from 35 to 699 patients, with the majority female between the ages of 35 and 48 years. Average disease duration ranged between 2.6 and 13.8 years. Multiple tools were used to evaluate CI, with most studies evaluating complex attention (n=19, 68%) and learning/memory (n=16, 57%). The Symbol Digit Modalities Test was the most used tool (n=13, 46%), followed by the Paced Auditory Serial Addition Test (n=11, 39%). Most included studies assessed the correlation between CI and depression (n=16, 57%), fatigue (n=9, 32%) and anxiety (n=7, 25%) using MS-specific and generic QoL tools. Studies found CI to be positively correlated with depression, fatigue, and stigma, and inversely correlated with social support, employment status, and mental health, regardless of cognitive domain. No correlations were identified between CI and anxiety, stress, or driving ability. High performance in general cognition was strongly associated with increased rates of employment. However, correlations, or lack thereof, varied based on cognitive domain being evaluated and across studies.

Conclusions: This review suggests that CI is associated with increased fatigue, depression and decreased social support, mental and physical QoL, and employment status. Study findings varied due to the plethora of outcome measures used. Further research is required to assess how CI impacts MS-related QoL and work productivity, including absenteeism, presenteeism, and lost wages.