Comorbidity in Multiple Sclerosis: Some Answers, More Questions

Cardiopulmonary exercise testing in people with minimally impaired multiple sclerosis

BACKGROUND

Multiple sclerosis (MS) is a chronic demyelinating inflammatory disorder of the central nervous system that may affect respiratory system at the later stages of the disease. The aim of our study was to evaluate respiratory function and cardiopulmonary exercise testing in ambulatory without aid people with MS (pwMS), and to investigate quality of life parameters and fatigue in this population.

METHODS

25 pwMS and 16 healthy controls were included in this study. Pulmonary function tests were performed and were followed by proper cardiopulmonary exercise testing with the use of treadmill. Quality of life assessment was done with SF-36 questionnaire.

RESULTS

The mean age of the patient group was 38.4 ± 8.2 years. Spirometric values were within normal limits, and so did lung diffusion capacity, while maximal voluntary ventilation was reduced. In cardiopulmonary exercise testing the patient group showed impairment compared to control group. The statistically significant lower parameters were V'O2 peak, V'CO2 peak, RER, V'O2/kg peak, V'CO2/kg peak, oxygen pulse peak and V'E/V'CO2 slope. Moreover, there was a negative and statistically significant correlation between CPET values and BMI and MFIS, while there was a positive and statistically significant correlation with quality of life, evaluated by SF-36.

CONCLUSION

Our study showed that the main cardiopulmonary exercise testing parameters were affected in ambulatory pwMS, even without evidence of respiratory symptoms. Therefore, these people should be evaluated for pulmonary function compromise.

Multiple Sclerosis Phenotypes as a Continuum: The Role of Neurologic Reserve

Purpose of Review

This review presents the hypothesis that loss of neurologic reserve explains onset of progressive multiple sclerosis (PrMS).

Recent Findings

Evidence supporting the separate classification of PrMS and relapsing multiple sclerosis (RMS) is limited and does not explain PrMS or the response of these patients to therapy.

Summary

We argue that multiple sclerosis (MS) progresses along a continuum from RMS to PrMS, with differing levels of neurologic reserve accounting for phenotypic differences. In early MS, inflammation causes brain atrophy with symptoms buffered by neurologic reserve. As brain loss from normal aging and MS continues, reserve is depleted and effects of subclinical MS disease activity and aging are unmasked, manifesting as PrMS. Most therapies show limited benefit in PrMS; patients are older, have fewer inflammatory events, and the effects of aging cause continued loss of neurologic function, even if inflammation is terminated. Loss of neurologic reserve means patients with PrMS cannot recover function, unlike patients with RMS.

Systematic Assessment of Medical Diagnoses Preceding the First Diagnosis of Multiple Sclerosis

OBJECTIVE

To explore the occurrence of diseases and symptoms in the 5 years before diagnosis in patients with multiple sclerosis (MS) in a case-control study.

METHODS

Using ambulatory claims data, we systematically assessed differences in the occurrence of diseases and symptoms in the 5 years before first diagnosis in patients with MS (n = 10,262) compared to patients with 2 other autoimmune diseases, Crohn disease (n = 15,502) and psoriasis (n = 98,432), and individuals without these diseases (n = 73,430).

RESULTS

Forty-three ICD-10 codes were recorded more frequently for patients with MS before diagnosis compared to controls without autoimmune disease. Many of these findings were confirmed in a comparison to the other control groups. A high proportion of these ICD-10 codes represent symptoms suggestive of demyelinating events or other neurologic diagnoses. In a sensitivity analysis excluding patients with such recordings before first diagnosis, no association remained significant. Seven ICD-10 codes were associated with lower odds ratios of MS, 4 of which represent upper respiratory tract infections. Here, the relations with MS were even more pronounced in the sensitivity analysis.

CONCLUSIONS

Our analyses suggest that patients with MS are frequently not diagnosed at their first demyelinating event but often years later. Symptoms and physician encounters before MS diagnosis seem to be related to already ongoing disease rather than a prodrome. The observed association of upper respiratory tract infections with lower odds ratios of MS diagnosis suggests a link between protection from infection and MS that, however, needs to be validated and further investigated.

Neurofilaments: neurobiological foundations for biomarker applications

Interest in neurofilaments has risen sharply in recent years with recognition of their potential as biomarkers of brain injury or neurodegeneration in CSF and blood. This is in the context of a growing appreciation for the complexity of the neurobiology of neurofilaments, new recognition of specialized roles for neurofilaments in synapses and a developing understanding of mechanisms responsible for their turnover. Here we will review the neurobiology of neurofilament proteins, describing current understanding of their structure and function, including recently discovered evidence for their roles in synapses. We will explore emerging understanding of the mechanisms of neurofilament degradation and clearance and review new methods for future elucidation of the kinetics of their turnover in humans. Primary roles of neurofilaments in the pathogenesis of human diseases will be described. With this background, we then will review critically evidence supporting use of neurofilament concentration measures as biomarkers of neuronal injury or degeneration. Finally, we will reflect on major challenges for studies of the neurobiology of intermediate filaments with specific attention to identifying what needs to be learned for more precise use and confident interpretation of neurofilament measures as biomarkers of neurodegeneration.

Precision medicine in the multiple sclerosis clinic: Selecting the right patient for the right treatment

Multiple sclerosis (MS) is a chronic, inflammatory disease of the central nervous system (CNS), affecting patients of all ages, causing neurologic disability if inadequately treated. Some patients have a relatively benign disease course without significant disability after decades, while a more aggressive course ensues in others and disability progression occurs after only several years. Certain risk factors confer a higher chance of a patient having aggressive MS. Currently over 15 disease-modifying treatments (DMTs) are approved for MS with different efficacy and safety profiles. Deciding which DMT to use in a specific patient requires a careful analysis of a patient’s disease course for high-risk factors for early progression, consideration of the efficacy and safety profile for potential therapy, as well as understanding of a patient’s lifestyle and expectations. The integration of these factors is the art of precision medicine, a necessary practice in the treatment of patients with MS.

Progressive familial intrahepatic cholestasis type-3 and multiple sclerosis: lessons from comorbidity

The comorbidity between multiple sclerosis (MS) and progressive familial intrahepatic cholestasis type‐3 (PFIC3) has never been described yet. ABCB4 gene encodes the multidrug resistant protein 3 (MDR3) and its mutations induce PFIC3 as well as intrahepatic cholestasis of pregnancy (ICP) and drug‐induced liver injury (DILI). We describe the case of a 32‐year‐old female with MS and PFIC3 who was effectively treated with natalizumab and ursodeoxycholic acid (UCDA), in contrast to glatiramer acetate, dimethylfumarate, and IFNb1a associated with DILI. Our findings clarify the pharmacodynamics of MS therapies and suggest natalizumab plus UDCA as the effective treatment of PFIC3/MS phenotype, unlike the others that should be avoided.

Blood pressure and body fat percent in women with NMOSD

BACKGROUND

Hypertension is a prevalent and impactful comorbid condition among patients with multiple sclerosis (MS). High level of body mass index (BMI) is associated with the risk and poor outcomes of neuromyelitis optica spectrum disorder (NMOSD) in women. However, the clinical implication of blood pressure (BP) and body fat percent (BF%) based on the Clínica Universidad de Navarra-Body Adiposity Estimator (CUN-BAE) in NMOSD has not been investigated thus far.

METHODS

Case data were collected from 47 NMOSD and 28 MS patients at acute phase, 21 NMOSD and 25 MS patients at stable phase, and 68 age- and sex-matched HCs. Four BP measures including systolic BP (SBP), diastolic BP (DBP), pulse pressure (PP), and mean arterial pressure (MAP); BMI; and BF% between NMOSD, MS, and healthy controls were determined.

RESULTS

Comparing NMOSD patients with MS patients, the former have significantly higher SBP (p < 0.001), DBP (p < 0.001), PP (p < 0.001), MAP (p < 0.001), BF% (p = 0.001), and BMI (p < 0.001) levels at acute phase after adjusting for age. Acute myelitis (OR 3.719, 95% CI 1.110-12.453) is more likely to occur in NMOSD patients with high BF% (≥30%) at acute phase. BF% was negatively correlated with 1/AQP4 titer in NMOSD at acute phase (r = -0.522, p = 0.004).

CONCLUSIONS

Women with NMOSD are probably more prone to have an increased BP and fat mass compared to MS.

Education, and the balance between dynamic and stationary functional connectivity jointly support executive functions in relapsing-remitting multiple sclerosis

Graphical network characteristics and nonstationary functional connectivity features, both derived from resting-state functional magnetic resonance imaging (rsfMRI) data, have been associated with cognitive performance in healthy subjects. How these features jointly relate to cognition in diseased states has not been investigated. In this study, 46 relapsing-remitting multiple sclerosis subjects underwent rsfMRI scans and a focused cognitive battery. With a sliding window approach, we examined six dynamic network features that indicated how connectivity changed over time as well as six measures derived from graph theory to reflect static network characteristics. Multiset canonical correlation analysis (MCCA) was then carried out to investigate the relations between dynamic network features, stationary network characteristics, cognitive testing, demographic, disease severity, and mood. Multiple sclerosis (MS) subjects demonstrated weaker connectivity strength, decreased network density, reduced global changes, but increased changes in interhemispheric connectivity compared to controls. The MCCA model determined that executive functions and processing speed ability measured by Wechsler Adult Intelligence Scale IV (WAIS-IV) Working Memory Index, WAIS-IV Processing Speed Index, and the Verbal Fluency Test were positively correlated with education, dynamic connectivity, and static connectivity strength; while poor task switching was correlated with disease severity, psychiatric comorbidities such as depression, anxiety, and fatigue, and static network density. Taken together, our results suggest that better executive functioning in MS requires maintenance of a continued coordination between stationary and dynamic functional connectivity as well as the support of education, and dynamic functional connectivity may provide an additional cognitive biomarker of disease severity in the MS population.

Exploring the role of physical activity and exercise for managing vascular comorbidities in people with multiple sclerosis: A scoping review

INTRODUCTION

Vascular comorbidities are prevalent among people with multiple sclerosis (MS) and have adverse disease-related consequences. In the general population, physical activity (PA) and exercise training have proven beneficial at all levels of vascular disease risk management. People with MS exhibit particularly low rates of PA; therefore, PA represents a modifiable health behavior for potentially managing vascular comorbidity risk in MS, and in turn, reducing disease burden. However, points of evidence justifying such an approach have yet to be summarized.

OBJECTIVE

To conduct a scoping review of existing evidence linking PA and exercise training to potential modification of vascular comorbidities and related risk factors in people with MS.

METHODS

We searched five electronic databases (PubMed, Ovid MEDLINE, Embase, PsycINFO, and CINAHL Plus) from inception to November 2017, for articles involving relevant vascular comorbidities (obesity, hyperlipidemia, heart disease, hypertension, and diabetes) in people with MS in conjunction with measures of PA, physical fitness, sedentary behavior, or exercise training. Studies were limited to English-language and primary research articles. Data were extracted and summarized by comorbidity type and study design (observational vs. interventional).

RESULTS

Our initial search identified 1028 articles; subsequent screening resulted in 34 articles meeting the final inclusion criteria, including both observational (n = 17) and interventional (n = 17) studies. Most of the articles reported on obesity (n = 29), although evidence surrounding hyperlipidemia (n = 5), arterial function and hypertension (n = 5), and diabetes (n = 5) was also identified. Data supporting a beneficial role for PA or exercise training could be drawn from each comorbidity category. Overall, 14 of the 17 observational studies identified (82.4%) reported an association between higher levels of PA or cardiorespiratory fitness, or decreased sedentary behavior, and better function of at least one risk factor related to vascular comorbid conditions in people with MS. The efficacy of exercise training in limiting vascular comorbidity risk and burden was dependent upon intervention type and duration, with 9 of 17 interventional studies (52.9%) reporting improvement in at least one relevant measure of vascular comorbidity in participants with MS.

CONCLUSIONS

Evidence points to a potential relationship between PA and exercise and risk factors related to vascular comorbidities in people with MS. PA and exercise training interventions may represent an effective therapeutic strategy for managing vascular comorbidities in people with MS, justifying further investigation.

Body mass index and cardiorespiratory fitness in persons with multiple sclerosis

OBJECTIVE

This study examined body fatness and its association with cardiorespiratory fitness (CRF) in persons with multiple sclerosis (pwMS) accounting for disability status.

MATERIALS AND METHODS

This study involved a secondary data analysis from a previous study of 62 pwMS. Body fatness was indirect measured as body mass index (BMI), and CRF was measured as peak oxygen consumption from an incremental exercise test with spirometry. Participants were allocated into 3 different groups based on established BMI categories (ie, normal, overweight, and obese), and data were analyzed using SPSS.

RESULTS

The average BMI was 27.0 (6.7) kg/m² , and CRF was 19.5 (7.2) mL/kg/min. There was an inverse correlation (pr = -.38 [-.57; -.14]; P = .003) between BMI and CRF controlling for age, sex, disease duration, and disability level. ANCOVA with linear contrast analysis revealed a statistical significant reduction in CRF between groups of different BMI categories; normal weight 20.8 (0.85); overweight 19.8 (1.13); and obese 16.9 (1.73) mL/kg/min; F (2, 55) = 3.33, P = .043; η²  = .11.

CONCLUSIONS

The findings suggest that BMI has a negative impact on CRF in pwMS, with a marked reduction in CRF for those classified as obese compared to those in the normal and overweight category.

Comorbidity and metabolic syndrome in patients with multiple sclerosis from Asturias and Catalonia, Spain

BACKGROUND

The impact of comorbidity on multiple sclerosis (MS) is a new area of interest. Limited data on the risk factors of metabolic syndrome (MetS) is currently available. The aim of this study was to estimate the presence of comorbid conditions and MetS in a sample of adult patients with MS.

METHODS

A retrospective, cohort study was conducted using electronic medical records from 19 primary care centres in Catalonia and Asturias, Spain. The number of chronic diseases (diagnoses), the Charlson Comorbidity Index and the individual Case-mix Index were used to assess general comorbidity variables. MetS was defined using the National Cholesterol Education Program Adult Treatment Panel III. Patients were distributed into two groups according to the Expanded Disability Status Scale (EDSS) score: 0-3.5 and 4-10.

RESULTS

A total of 222 patients were studied (mean age = 45.5 (SD 12.5) years, 64.4% were female and 62.2% presented a diagnosis of relapsing-remitting MS). Mean EDSS score was 3.2 (SD 2.0). Depression (32.4%), dyslipidaemia (31.1%), hypertension (23.0%) and obesity (22.5%) were the most common comorbidities. Overall MetS prevalence was 31.1% (95% CI: 25.0-37.2%). Patients with an EDSS ≥ 4.0 showed a significantly higher number of comorbidities (OR=2.2; 95% CI: 1.7-3.0; p<0.001).

CONCLUSION

MS patients had a high prevalence of MetS. Screening for comorbidity should be part of standard MS care. Further studies are necessary to confirm this association and the underlying mechanisms of MS and its comorbidities.

Development and validation of a claims-based measure as an indicator for disease status in patients with multiple sclerosis treated with disease-modifying drugs

Background

Administrative healthcare claims data provide a mechanism for assessing and monitoring multiple sclerosis (MS) disease status across large, clinically representative “real-world” populations. The estimation of MS disease status using administrative claims can be a challenge, however, due to a lack of detailed clinical information. Retrospective claims analyses in MS have traditionally used rates of MS relapses to approximate disease status. Healthcare costs may be alternate, broader claims-based indicators of disease activity because costs reflect multiple facets of care of patients with MS, and there is a strong correlation between quality of life of patients with MS and costs of the disease. This study developed, tested, and validated a healthcare cost-based measure to serve as an indicator of overall disease status in patients with MS treated with disease-modifying drugs (DMDs) utilizing administrative claims.

Methods

Using IMS Health Real World Data Adjudicated Claims – US data (January 2006–June 2013), a negative binomial regression predicted annual all-cause medical costs. Coefficients reaching statistical significance (p < 0.05) and increasing costs by ≥5% were selected for inclusion into an MS-specific severity score (scale of 0 to 100). Components of the score included rehabilitation services, altered mental state, pain, disability, stiffness, balance disorder, urinary incontinence, numbness, malaise/fatigue, and infections. Coefficient weights represented each predictor’s contribution. The predictive model was derived using 50% of a random sample and tested/validated using the remaining 50%.

Results

Average overall predicted annual total medical cost was $11,134 (development sample, n = 11,384, vs. $10,528 actual) and $11,303 (validation sample, n = 11,385, vs. $10,620 actual). The model had consistent bias (approximately +$600 or +6% of actual costs) for both samples. In the validation sample, mean MS disease status scores were 0.24, 8.95, and 21.77 for low, medium, and high tertiles, respectively. Mean costs were most accurately predicted among less severe patients ($5243 predicted vs. $5233 actual cost for lowest tertile).

Conclusion

The algorithm developed in this study provides an initial step to helping understand and potentially predict cost changes for a commercially insured MS population.

Electronic supplementary material

The online version of this article (doi:10.1186/s12883-017-0887-1) contains supplementary material, which is available to authorized users.