Comorbidity in multiple sclerosis: Emphasis on patient-reported outcomes

Background: Aim of our study was to estimate the prevalence of comorbid conditions and adverse health behaviors in relapsing-remitting multiple sclerosis (RRMS) patients and evaluate association between comorbidity and MS outcomes (relapse rate, fatigue and quality of life) in Lithuanian setting. Methods: A prospective cohort study was carried out in the MS center of Lithuanian University of Health Sciences Hospital Kaunas clinics from November 2016 to March 2021. People with MS filled a self-report comorbidity and adverse health behavior questionnaire, visual analogue fatigue scale (VAFS), a Short Form 36 (SF-36) v2 health related quality of life questionnaire (QoL). Information about disability and relapses was acquired from medical documentation and Lithuanian MS registry at baseline and after 24-month observational period. Chi square, t test, ANOVA, Mann-Whitney U were used for basic statistical evaluation. Multivariable logistic regression models were used to prognose MS outcomes in association to comorbidity and adverse health behaviors, adjusting for age and baseline disability. Results: Of 230 RRMS patients, 167 (72.6%) were women, average age was 42 years. 207 persons were followed through the observational period and included into relapse analysis. 112 (48.7%) of participants reported having at least one comorbidity, the most prevalent were arterial hypertension (19.1%) depression (16.5%) and anxiety (14.8%). People with comorbidities had higher fatigue (6.6 vs. 5.3, p < 0.001) and lower quality of life (overall SF-36 46.3 vs 59.1, p < 0.001). People consuming alcohol had fewer relapses per 24 months (0.56 vs. 0.82, p = 0.01), lower fatigue (5.7 vs. 6.4, p = 0.03), better quality of life (overall SF-36: 56.8 vs. 45.6, p < 0.001), compared to abstinents. In regression models, comorbidities were associated with severe (> 7 VAFS) fatigue (Exp(B)=1.98, 95% CI [1.02, 3.86], p = 0.043), diminished (< 50 SF-36) QoL (Exp(B)=3.50, 95% CI [1.72, 7.09], p = 0.001). Depression was independently associated with lower QoL (Exp(B)= 2.86, 95% CI [1.04, 7.88], p = 0.042) and severe fatigue (Exp (B)=4.65, 95% CI [2.39, 9.01], p < 0.001); anxiety with diminished QoL (Exp(B)= 4.99, 95%CI [1.67, 14.92], p = 0.002). Light alcohol consumption (compared to abstinents) was associated with decreased risk for: relapse during 24 months (Exp(B)=0.44, 95% CI[0.24, 0.77], p = 0.005), severe fatigue (Exp(B)=0.48, 95% CI [0.24, 0.98], p = 0.042) and lower QoL (Exp(B)= 0.32, 95% CI [0.16, 0.65], p = 0.002). Conclusion: Comorbidity is a relevant issue in multiple sclerosis as half of people with MS report concomitant conditions. Hypertension, depression, and anxiety are especially prevalent in MS. In our study, comorbidity is associated with quality of life and fatigue, but not relapse rate. Depression and anxiety are independently associated with lower quality of life and higher fatigue. Light alcohol consumption is associated with reduced relapse risk, less fatigue and better quality of life. Overweight and tobacco smoking do not seem to have negative impact on MS outcomes in our sample.