Kyla A. McKay

Health-related quality of life in multiple sclerosis: Direct and indirect effects of comorbidity.

Objective: To evaluate the direct and indirect influences of physical comorbidity, symptoms of depression and anxiety, fatigue, and disability on health-related quality of life (HRQoL) in persons with multiple sclerosis (MS). Methods: A large (n = 949) sample of adults with MS was recruited from 4 Canadian MS clinics. HRQoL was assessed using the patient-reported Health Utilities Index Mark 3. Expanded Disability Status Scale scores, physical comorbidity, depression, anxiety, and fatigue were evaluated as predictors of HRQoL in a cross-sectional path analysis. Results: All predictors were significantly associated with HRQoL and together accounted for a large proportion of variance (63%). Overall, disability status most strongly affected HRQoL (β = −0.52) but it was closely followed by depressive symptoms (β = −0.50). The direct associations of physical comorbidity and anxiety with HRQoL were small (β = −0.08 and −0.10, respectively), but these associations were stronger when indirect effects through other variables (depression, fatigue) were also considered (physical comorbidity: β = −0.20; anxiety: β = −0.34). Conclusions: Increased disability, depression and anxiety symptoms, fatigue, and physical comorbidity are associated with decreased HRQoL in MS. Disability most strongly diminishes HRQoL and, thus, interventions that reduce disability are expected to yield the most substantial improvement in HRQoL. Yet, interventions targeting other factors amenable to change, particularly depression but also anxiety, fatigue, and physical comorbidities, may all result in meaningful improvements in HRQoL, as well. Our findings point to the importance of further research confirming the efficacy of such interventions.

Factors associated with onset, relapses or progression in multiple sclerosis: A systematic review

&NA; Multiple sclerosis (MS) is a chronic disease of the central nervous system with an unidentified etiology. We systematically reviewed the literature on the possible risk factors associated with MS disease onset, relapses and progression from 1960 to 2012 by accessing six databases and including relevant systematic reviews, meta‐analyses, case‐control or cohort studies. The focus was on identifying modifiable risk factors. Fifteen systematic reviews and 169 original articles were quality assessed and integrated into a descriptive review. Best evidence, which included one or more prospective studies, suggested that lower exposure to sunlight and/or lower serum vitamin D levels were associated with an increased risk of developing MS onset and subsequent relapses, but a similar quality of evidence was lacking for disease progression. Prospective studies indicated that cigarette smoking may increase the risk of MS as well as accelerate disease progression, but whether smoking altered the risk of a relapse was largely unknown. Infections were implicated in both risk of developing MS and relapses, but data for progression were lacking. Specifically, exposure to the Epstein‐Barr virus, particularly if this manifested as infectious mononucleosis during adolescence, was associated with increased MS risk. Upper respiratory tract infections were most commonly associated with an increase in relapses. Relapse rates typically dropped during pregnancy, but there was no strong evidence to suggest that pregnancy itself altered the risk of MS or affected long‐term progression. Emerging research with the greatest potential to impact public health was the suggestion that obesity during adolescence may increase the risk of MS; if confirmed, this would be of major significance.

Risk Factors Associated with the Onset of Relapsing-Remitting and Primary Progressive Multiple Sclerosis: A Systematic Review

Multiple sclerosis (MS) is a chronic central nervous system disease with a highly heterogeneous course. The aetiology of MS is not well understood but is likely a combination of both genetic and environmental factors. Approximately 85% of patients present with relapsing-remitting MS (RRMS), while 10–15% present with primary progressive MS (PPMS). PPMS is associated with an older onset age, a different sex ratio, and a considerably more rapid disease progression relative to RRMS. We systematically reviewed the literature to identify modifiable risk factors that may be associated with these different clinical courses. We performed a search of six databases and integrated twenty observational studies into a descriptive review. Exposure to Epstein-Barr virus (EBV) appeared to increase the risk of RRMS, but its association with PPMS was less clear. Other infections, such as human herpesvirus-6 and chlamydia pneumoniae, were not consistently associated with a specific disease course nor was cigarette smoking. Despite the vast literature examining risk factors for the development of MS, relatively few studies reported findings by disease course. This review exposes a gap in our understanding of the risk factors associated with the onset of PPMS, our current knowledge being predominated by relapsing-onset MS.

Cholesterol and markers of cholesterol turnover in multiple sclerosis: relationship with disease outcomes

Multiple sclerosis (MS) is a chronic central nervous system disease that is associated with progressive loss of myelin and subsequent axonal degeneration. Cholesterol is an essential component of mammalian cellular and myelin membranes. In this systematic review, we examined the relationship between levels of cholesterol and markers of cholesterol turnover in circulation and/or cerebrospinal fluid (CSF) and disease outcomes in adults with clinically isolated syndrome (CIS) or confirmed MS. Studies suggest that elevated levels of circulating low density lipoprotein cholesterol (LDL), total cholesterol, and particularly, apolipoprotein B and oxidized LDL are associated with adverse clinical and MRI outcomes in MS. These relationships were observed as early as CIS. The studies also suggest that oxysterols, cholesterol precursors, and apolipoprotein E may be markers of specific disease processes in MS, but more research is required to elucidate these processes and relationships. Taken together, the data indicate that cholesterol and markers of cholesterol turnover have potential to be used clinically as biomarkers of disease activity and may even be implicated in the pathogenesis of MS.

Adverse health behaviours are associated with depression and anxiety in multiple sclerosis: A prospective multisite study.

Background: Depression and anxiety are common among people with multiple sclerosis (MS), as are adverse health behaviours, but the associations between these factors are unclear. Objective: To evaluate the associations between cigarette smoking, alcohol use, and depression and anxiety in MS in a cross-Canada prospective study. Methods: From July 2010 to March 2011 we recruited consecutive MS patients from four MS clinics. At three visits over two years, clinical and demographic information was collected, and participants completed questionnaires regarding health behaviours and mental health. Results: Of 949 participants, 75.2% were women, with a mean age of 48.6 years; most had a relapsing−remitting course (72.4%). Alcohol dependence was associated with increased odds of anxiety (OR: 1.84; 95% CI: 1.32–2.58) and depression (OR: 1.53; 95% CI: 1.05–2.23) adjusting for age, sex, Expanded Disability Status Scale (EDSS), and smoking status. Smoking was associated with increased odds of anxiety (OR: 1.29; 95% CI: 1.02–1.63) and depression (OR: 1.37; 95% CI: 1.04–1.78) adjusting for age, sex, EDSS, and alcohol dependence. Alcohol dependence was associated with an increased incidence of depression but not anxiety. Depression was associated with an increased incidence of alcohol dependence. Conclusion: Alcohol dependence and smoking were associated with anxiety and depression. Awareness of the effects of adverse health behaviours on mental health in MS might help target counselling and support for those ‘at risk’.

Comorbidity is associated with pain-related activity limitations in multiple sclerosis

BACKGROUND Comorbidities are common in multiple sclerosis (MS). The high prevalence of pain in MS is well-established but the influence of comorbidities on pain, specifically, pain-related interference in activity is not. OBJECTIVE To examine the relationship between comorbidity and pain in MS. METHODS We recruited 949 consecutive patients with definite MS from four Canadian centres. Participants completed the Health Utilities Index (HUI-Mark III) and a validated comorbidity questionnaire at 3 visits over 2 years. The HUIs pain scale was dichotomized into two groups: those with/without pain that disrupts normal activities. We used logistic regression to assess the association of pain with each comorbidity individually at baseline and over time. RESULTS The incidence of disruptive pain over two years was 31.1 per 100 persons. Fibromyalgia, rheumatoid arthritis, irritable bowel syndrome, migraine, chronic lung disease, depression, anxiety, hypertension, and hypercholesterolemia were associated with disruptive pain (p<0.006). Individual-level effects on the presence of worsening pain were seen for chronic obstructive pulmonary disease (odds ratio [OR]: 1.50 95% CI: 1.08-2.09), anxiety (OR: 1.49 95% CI: 1.07-2.08), and autoimmune thyroid disease (OR: 1.40 95% CI: 1.00-1.97). CONCLUSION Comorbidity is associated with pain in persons with MS. Closer examination of these associations may provide guidance for better management of this disabling symptom in MS.

Determinants of non-adherence to disease-modifying therapies in multiple sclerosis: A cross-Canada prospective study

Background: Poor adherence to the disease-modifying therapies (DMTs) for multiple sclerosis (MS) may attenuate clinical benefit. A better understanding of characteristics associated with non-adherence could improve outcomes. Objective: To evaluate characteristics associated with non-adherence to injectable DMTs. Methods: Consecutive patients from four Canadian MS Clinics were assessed at three time points over two years. Clinical and demographic information included self-reported DMT use, missed doses in the previous 30 days, health behaviors, and comorbidities. Non-adherence was defined as <80% of expected doses taken. We employed generalized estimating equations to examine characteristics associated with non-adherence at all time points with findings reported as adjusted odds ratios (OR). Results: In all, 485 participants reported use of an injectable DMT, of whom 107 (22.1%) were non-adherent over the study period. Non-adherence was associated with a lower Expanded Disability Status Scale score (0–2.5 vs 3.0–5.5, OR: 1.80; 95% confidence interval (CI): 1.06–3.04), disease duration (⩽5 vs <5 years, OR: 2.23; 95% CI: 1.10–4.52), alcohol dependence (OR: 2.14; 95% CI: 1.23–3.75), and self-reported cognitive difficulties, measured by the Health Utilities Index-3 (OR: 1.55; 95% CI: 1.08–2.22). Conclusions: Nearly one-quarter of participants were non-adherent during the study. Alcohol dependence, perceived cognitive difficulties, longer disease duration, and mild disability status were associated with non-adherence. These characteristics may help healthcare professionals identify patients at greatest risk of poor adherence.

Genetic variation associated with the occurrence and progression of neurological disorders.

This paper presents an overview of genetic variation associated with the onset and progression of 14 neurological disorders, focusing primarily on association studies. The 14 disorders are heterogeneous in terms of their frequency, age of onset, etiology and progression. There is substantially less evidence on progression than onset. With regard to onset, the conditions are diverse in terms of their epidemiology and patterns of familial aggregation. While the muscular dystrophies and Huntingtons disease are monogenic diseases, for the other 12 conditions only a small proportion of cases is associated with specific genetic syndromes or mutations. Excluding these, some familial aggregation remains for the majority of cases. There is considerable variation in the volume of evidence by condition, and by gene within condition. The volume of evidence is greatest for Alzheimers disease, Parkinsons disease, multiple sclerosis and amyotrophic lateral sclerosis. As for common complex chronic diseases, genome wide association studies have found that validated genomic regions account for a low proportion of heritability. Apart from multiple sclerosis, which shares several susceptibility loci with other immune-related disorders, variation at HLA-DRB5 being associated both with Parkinsons disease and Alzheimers disease, and the association of the C9orf72 repeat expansion with ALS and frontotemporal degeneration, there was little evidence of gene loci being consistently associated with more than one neurological condition or with other conditions. With the exception of spina bifida, for which maternal MTHFR genotype is associated with risk in the offspring, and corroborates other evidence of the importance of folate in etiology, there was little evidence that the pathways influenced by genetic variation are related to known lifestyle or environmental exposures.

Determinants of neurological disease: Synthesis of systematic reviews

&NA; Systematic reviews were conducted to identify risk factors associated with the onset and progression of 14 neurological conditions, prioritized as a component of the National Population Health Study of Neurological Conditions. These systematic reviews provided a basis for evaluating the weight of evidence of evidence for risk factors for the onset and progression of the 14 individual neurological conditions considered. A number of risk factors associated with an increased risk of onset for more than one condition, including exposure to pesticides (associated with an increased risk of AD, amyotrophic lateral sclerosis, brain tumours, and PD; smoking (AD, MS); and infection (MS, Tourette syndrome). Coffee and tea intake was associated with a decreased risk of onset of both dystonia and PD. Further understanding of the etiology of priority neurological conditions will be helpful in focusing future research initiatives and in the development of interventions to reduce the burden associated with neurological conditions in Canada and internationally. HighlightsWith population aging, the burden of neurological disease is increasing worldwide.Understanding the factors affecting the onset and progression of neurological disease through systematic review is essential for the development of strategies to reduce the burden of these diseases.Systematic review identified biological, demographic, environmental, genetic, lifestyle and pharmacological risk factors for specific neurological conditions.Several risk factors were associated with the onset of multiple conditions. Pesticides, for example, were associated with an increased risk of Alzheimers disease, amyotrophic lateral sclerosis, primary brain tumours, and Parkinsons disease.Helmet use was associated with a reduction in onset of neurotrauma, as well as all neurologic conditions for which head injury was a risk factor.The findings presented here should be viewed as provisional, pending a more in‐depth evaluation of the weight of evidence.Further research will also serve to fill current data gaps, particularly regarding risk factors for the progression of neurological disease.In the interim, the modifiable risk factors may be considered as potential candidates for the development of targeted interventions to reduce the burden of neurological disease in Canada and internationally.

Fatigue and Comorbidities in Multiple Sclerosis

BACKGROUND Fatigue is commonly reported by people with multiple sclerosis (MS). Comorbidity is also common in MS, but its association with the presence of fatigue or fatigue changes over time is poorly understood. METHODS Nine hundred forty-nine people with definite MS were recruited from four Canadian centers. The Fatigue Impact Scale for Daily Use and a validated comorbidity questionnaire were completed at three visits over 2 years. Participants were classified into groups with no fatigue versus any fatigue. Logistic regression was used to determine the relationship between fatigue and each comorbidity at baseline, year 1, year 2, and overall. RESULTS The incidence of fatigue during the study was 38.8%. The prevalence of fatigue was greater in those who were older (P = .0004), had a longer time since symptom onset (P = .005), and had greater disability (P < .0001). After adjustment, depression (odds ratio [OR], 2.58; 95% confidence interval [CI], 2.03-3.27), irritable bowel syndrome (OR, 1.71; 95% CI, 1.18-2.48), migraine (OR, 1.69; 95% CI, 1.27-2.27), and anxiety (OR, 1.57; 95% CI, 1.15-2.16) were independently associated with fatigue that persisted during the study. There was also an individual-level effect of depression on worsening fatigue (OR, 1.49; 95% CI, 1.08-2.07). CONCLUSIONS Comorbidity is associated with fatigue in MS. Depression is associated with fatigue and with increased risk of worsening fatigue over 2 years. However, other comorbid conditions commonly associated with MS are also associated with persistent fatigue, even after accounting for depression. Further investigation is required to understand the mechanisms by which comorbidities influence fatigue.