Prevalence and incidence of ischemic heart disease in multiple sclerosis: A population-based validation study

Current understanding of cardiovascular autonomic dysfunction in multiple sclerosis

Autoimmune diseases, including multiple sclerosis (MS), are proven to increase the likelihood of developing cardiovascular disease (CVD) due to a robust systemic immune response and inflammation. MS can lead to cardiovascular abnormalities that are related to autonomic nervous system dysfunction by causing inflammatory lesions surrounding tracts of the autonomic nervous system in the brain and spinal cord. CVD in MS patients can affect an already damaged brain, thus worsening the disease course by causing brain atrophy and white matter disease. Currently, the true prevalence of cardiovascular dysfunction and associated death rates in patients with MS are mostly unknown and inconsistent. Treating vascular risk factors is recommended to improve the management of this disease. This review provides an updated summary of CVD prevalence in patients with MS, emphasizing the need for more preclinical studies using animal models to understand the pathogenesis of MS better. However, no distinct studies exist that explore the temporal effects and etiopathogenesis of immune/inflammatory cells on cardiac damage and dysfunction associated with MS, particularly in the cardiac myocardium. To this end, a thorough investigation into the clinical presentation and underlying mechanisms of CVD must be conducted in patients with MS and preclinical animal models. Additionally, clinicians should monitor for cardiovascular complications while prescribing medications to MS patients, as some MS drugs cause severe CVD.

Stroke risk in multiple sclerosis: a critical appraisal of the literature

Observational studies suggest that the occurrence of stroke on multiple sclerosis (MS) patients is higher compared to the general population. MS is a heterogeneous disease that involves an interplay of genetic, environmental and immune factors. The occurrence of stroke is subject to a wide range of both modifiable and non-modifiable, short- and long-term risk factors. Both MS and stroke share common risk factors. The immune mechanisms that underlie stroke are similar to neurodegenerative diseases and are attributed to neuroinflammation. The inflammation in autoimmune diseases may, therefore, predispose to an increased risk for stroke or potentiate the effect of conventional stroke risk factors. There are, however, additional determinants that contribute to a higher risk and incidence of stroke in MS. Due to the challenges that are associated with their differential diagnosis, the objective is to present an overview of the factors that may contribute to increased susceptibility or occurrence of stroke in MSpatients by performing a review of the available to date literature. As both MS and stroke can individually detrimentally affect the quality of life of afflicted patients, the identification of factors that contribute to an increased risk for stroke in MS is crucial for the prompt implementation of preventative therapeutic measures to limit the additive burden that stroke imposes.

Sex and age differences in the Multiple Sclerosis prodrome

Background and objectives

Little is known of the potential sex and age differences in the MS prodrome. We investigated sex and age differences in healthcare utilization during the MS prodrome.

Methods

This was a population-based matched cohort study linking administrative and clinical data from British Columbia, Canada (population = 5 million). MS cases in the 5 years preceding a first demyelinating event ("administrative cohort;" n = 6,863) or MS symptom onset ("clinical cohort;" n = 966) were compared to age-, sex- and geographically-matched controls (n = 31,865/4,534). Negative binomial and modified Poisson models were used to compare the rates of physician visits and hospitalizations per international classification of diseases chapter, and prescriptions filled per drug class, between MS cases and controls across sex and age-groups (< 30, 30-49, ≥50 years).

Results

In the administrative cohort, males with MS had a higher relative rate for genitourinary-related visits (males: adjusted Rate Ratio (aRR) = 1.65, females: aRR = 1.19, likelihood ratio test P = 0.02) and antivertigo prescriptions (males: aRR = 4.72, females: aRR = 3.01 P < 0.01). Injury and infection-related hospitalizations were relatively more frequent for ≥50-year-olds (injuries < 30/30-49/≥50: aRR = 1.16/1.39/2.12, P < 0.01; infections 30-49/≥50: aRR = 1.43/2.72, P = 0.03), while sensory-related visits and cardiovascular prescriptions were relatively more common in younger persons (sensory 30-49/≥50: aRR = 1.67/1.45, P = 0.03; cardiovascular < 30/30-49/≥50: aRR = 1.56/1.39/1.18, P < 0.01). General practitioner visits were relatively more frequent in males (males: aRR = 1.63, females: aRR = 1.40, P < 0.01) and ≥50-year-olds (< 30/≥50: aRR = 1.32/1.55, P = 0.02), while differences in ophthalmologist visits were disproportionally larger among younger persons, < 50-years-old (< 30/30-49/≥50: aRR = 2.25/2.20/1.55, P < 0.01). None of the sex and age-related differences in the smaller clinical cohort reached significance (P ≥ 0.05).

Discussion

Sex and age-specific differences in healthcare use were observed in the 5 years before MS onset. Findings demonstrate fundamental heterogeneity in the MS prodromal presentation.

Prevalence of chronic comorbidities in people with multiple sclerosis: descriptive study based on administrative data in Tuscany (Central Italy)

Objective

Chronic comorbidities are common in people with multiple sclerosis (PwMS), thus worsening their prognosis and quality of life, and increasing disease burden. The aim of the present study was to evaluate the prevalence of common comorbidities in PwMS in Tuscany (Central Italy) and to compare it with the general population.

Methods

The prevalence of comorbidities, including diabetes, chronic obstructive pulmonary disease (COPD), hypertension, stroke, heart failure (HF), cardiac infarction and ischemic heart disease (IHD), was assessed in PwMS and in general population resident in Tuscany, aged > 20 years, using administrative data.

Results

In total, we identified 8,274 PwMS. Among them, 34% had at least one comorbidity, with hypertension being the most common (28.5%). Comparing PwMS with the general population, PwMS had a higher frequency of hypertension and stroke when considering the whole group, and of diabetes, COPD, and IHD when considering sex and age subgroups. This increased risk was especially evident in the young and intermediate age groups, where multiple sclerosis may play an important role as risk factor for some comorbidities.

In PwMS, as well as in the general population, prevalence of chronic diseases was higher in males and increased with age.

Conclusions

Comorbidities frequently coexist with multiple sclerosis and they may have an impact on this complex disease, from the health, clinical, and socioeconomic points of view. Therefore, a routine screening of chronic comorbidities should be a crucial step in clinical practice, as well as the promotion of healthy lifestyles to prevent the onset and to reduce their burden.

Multiple sclerosis is associated with low bone mineral density and osteoporosis

Objective

To compare measures of bone mineral density (BMD) between people with and without MS.

Methods

Using population-based administrative data from Manitoba, Canada, we identified people with MS who received BMD screening and controls who received BMD screening matched 5:1 on age, sex, region of residence, and date of BMD screening. We determined the BMD T-scores for the femoral neck, total hip, and lumbar spine and frequency of osteoporosis (defined as T-score -2.5 or lower). We compared the groups with respect to the femoral neck T-score using multivariable linear regression, adjusting for age, sex, region, disability, continuity of care, recent previous fracture, falls history, medication use, and comorbidities. We compared the odds of osteoporosis between groups using multivariable logistic regression analysis.

Results

We identified 783 MS cases who underwent BMD screening and 3,915 matched controls. The mean (SD) femoral BMD T-score was lower in MS cases (-1.48 [1.08]) than in matched controls (-1.12 [0.98], p < 0.001), and the prevalence of osteoporosis was higher among the MS cases (range across BMD sites: 16%-26%) vs controls (6%-15%). MS was associated with a lower femoral neck BMD T-score after accounting for covariates (β = -0.24; 95% CI: -0.32 to -0.17) and more than 2-fold increased odds of osteoporosis (covariate-adjusted OR 2.41; 95% CI: 1.82-3.19).

Conclusions

People with MS have lower BMD and a higher prevalence of osteoporosis compared with people of similar age and sex without MS. These findings indicate the importance of addressing bone health as part of comprehensive MS care.

Five years before multiple sclerosis onset: Phenotyping the prodrome

BACKGROUND

The multiple sclerosis (MS) prodrome is poorly characterized.

OBJECTIVE

To phenotype the MS prodrome via health care encounters.

METHODS

Using data from a population-based cohort study linking administrative and clinical data in four Canadian provinces, we compared physician and hospital encounters and prescriptions filled (via International Classification of Diseases chapters, physician specialty or drug classes) for MS subjects in the 5 years before the first demyelinating claim in an administrative cohort or the clinical symptom onset in an MS clinic-derived cohort, to age-, sex- and geographically matched controls. Rate ratios (RRs), 95% confidence intervals (95% CIs) and proportions were estimated.

RESULTS

The administrative and clinical cohorts included 13,951/66,940 and 3202/16,006 people with and without MS (cases/controls). Compared to controls, in the 5 years before the first demyelinating claim or symptom onset, cases had more physician and hospital encounters for the nervous (RR (range) = 2.31; 95% CI: 1.05-5.10 to 4.75; 95% CI: 3.11-7.25), sensory (RR (range) = 1.40; 95% CI: 1.34-1.46 to 2.28; 95% CI: 1.72-3.02), musculoskeletal (RR (range) = 1.19; 95% CI: 1.07-1.33 to 1.70; 95% CI: 1.57-1.85) and genito-urinary systems (RR (range) = 1.17; 95% CI: 1.05-1.30 to 1.59; 95% CI: 1.48-1.70). Cases had more psychiatrist and urologist encounters (RR (range) = 1.48; 95% CI: 1.36-1.62 to 1.80; 95% CI: 1.61-2.01), and higher proportions of musculoskeletal, genito-urinary or hormonal-related prescriptions (1.1-1.5 times higher, all p < 0.02). However, cases had fewer pregnancy-related encounters than controls (RR = 0.78; 95% CI: 0.71-0.86 to 0.88; 95% CI: 0.84-0.92).

CONCLUSION

Phenotyping the prodrome 5 years before clinical recognition of MS is feasible.

Psychiatric comorbidity is associated with disability progression in multiple sclerosis

OBJECTIVE

Emerging evidence suggests that comorbidity may influence disability outcomes in multiple sclerosis (MS); we investigated the association between psychiatric comorbidity and MS disability progression in a large multiclinic population.

METHODS

This retrospective cohort study accessed prospectively collected information from linked clinical and population-based health administrative databases in the Canadian provinces of British Columbia and Nova Scotia. Persons with MS who had depression, anxiety, or bipolar disorder were identified using validated algorithms using physician and hospital visits. Multivariable linear regression models fitted using an identity link with generalized estimating equations were used to determine the association between psychiatric comorbidity and disability using all available Expanded Disability Status Scale (EDSS) scores.

RESULTS

A total of 2,312 incident cases of adult-onset MS were followed for a mean of 10.5 years, during which time 35.8% met criteria for a mood or anxiety disorder. The presence of a mood or anxiety disorder was associated with a higher EDSS score (β coefficient = 0.28, p = 0.0002, adjusted for disease duration and course, age, sex, socioeconomic status, physical comorbidity count, and disease-modifying therapy exposure). Findings were statistically significant among women (β coefficient = 0.31, p = 0.0004), but not men (β coefficient 0.22, p = 0.17).

CONCLUSION

Presence of psychiatric comorbidities, which were common in our incident MS cohort, increased the severity of subsequent neurologic disability. Optimizing management of psychiatric comorbidities should be explored as a means of potentially mitigating disability progression in MS.

Lower prevalence of multiple sclerosis in First Nations Canadians

Background

We compared the incidence and prevalence of multiple sclerosis (MS) between First Nations (FN) and non-FN populations in Manitoba.

Methods

We applied previously validated algorithms to population-based administrative (health claims) data from Manitoba, Canada, to identify all persons with MS from 1984 to 2011. We identified FN individuals using the Municipality of Registration field held at Manitoba Health. We compared the incidence and prevalence of MS between the FN and non-FN populations using negative binomial models.

Results

From 1984 to 2011, 5,738 persons had MS, of whom 64 (1.1%) were of FN ethnicity. The average annual incidence rate per 100,000 population was 8.15 (95% confidence interval [CI] 5.98–11.1) in the FN population and 15.7 (95% CI 15.1–16.3) in the non-FN population (incidence rate ratio 0.52; 95% CI 0.38–0.71). In 1984, the crude prevalence of MS per 100,000 population was 35.8 (95% CI 14.9–86.1) in the FN population and 113.3 (95% CI 106.3–120.8) in the non-FN population. Between 1984 and 2011, the age-standardized prevalence of MS increased by 351% to 188.5 (95% CI 146.6–230.4) in the FN population. In contrast, the prevalence of MS per 100,000 general population increased by 225%–418.4% (95% CI 405.8–431.0).

Conclusions

The incidence and prevalence of MS are twofold lower in the FN population than the non-FN population. Nonetheless, the prevalence of MS in FN Manitobans is higher than in other indigenous populations outside Canada. Given reports of more rapid disability progression among FN Canadians with MS, and the rising prevalence of MS in this population, attention should be directed to the needs of this population.

Effects of physical comorbidities on disability progression in multiple sclerosis

OBJECTIVE

To examine the association between physical comorbidities and disability progression in multiple sclerosis (MS).

METHODS

We conducted a retrospective cohort study using linked health administrative and clinical databases in 2 Canadian provinces. Participants included adults with incident MS between 1990 and 2010 who entered the cohort at their MS symptom onset date. Comorbidity status was identified with validated algorithms for health administrative data and was measured during the 1 year before study entry and throughout the study period. The outcome was the Expanded Disability Status Scale (EDSS) score as recorded at each clinic visit. We used generalized estimating equations to examine the association between physical comorbidities and EDSS scores over time, adjusting for sex, age, cohort entry year, use of disease-modifying drugs, disease course, and socioeconomic status. Meta-analyses were used to estimate overall effects across the 2 provinces.

RESULTS

We identified 3,166 individuals with incident MS. Physical comorbidity was associated with disability; with each additional comorbidity, there was a mean increase in the EDSS score of 0.18 (95% confidence interval [CI] 0.09-0.28). Among specific comorbidities, the presence of ischemic heart disease (IHD) or epilepsy was associated with higher EDSS scores (IHD 0.31, 95% CI 0.01-0.61; epilepsy 0.68, 95% CI 0.11-1.26).

CONCLUSIONS

Physical comorbidities are associated with an apparent increase in MS disability progression. Appropriate management of comorbidities needs to be determined to optimize outcomes.

Exercise interventions in multiple sclerosis rehabilitation need better reporting on comorbidities: a systematic scoping review

OBJECTIVE

To identify the extent to which exercise intervention studies in multiple sclerosis rehabilitation are addressing comorbidities and if researchers consider comorbidities as possible moderators or mediators of exercise outcomes.

METHODS

Five databases were searched from inception to January 8, 2016, for exercise-related terms in combination with multiple sclerosis. Studies were screened and limited to randomized control trials, full text, and English language. We assessed whether comorbidities were excluded or included, how they were reported and described, and if they were examined as possible moderators or mediators of exercise outcomes.

RESULTS

We reviewed 99 articles that included various exercise interventions, where the most common were general multi-faceted exercise training ( n=34), cardiovascular training ( n=18), progressive-resistance training ( n=12), and balance and gait training ( n=12). In total, 77 of 99 studies reported one or more comorbidities as an exclusion criterion. The most commonly excluded comorbidities were cardiovascular diseases, cognitive impairments or psychiatric disorders, and unspecified conditions or contraindications. Only nine studies reported details on excluded participants with comorbidities. Across studies that reported comorbidities of included participants ( n=8), none examined comorbidities as possible moderators or mediators of exercise outcomes.

CONCLUSION

Although a variety of exercise interventions have positive outcomes, there is limited evidence that these interventions are generalizable to people with multiple sclerosis who have comorbid conditions.

Infection-related health care utilization among people with and without multiple sclerosis

BACKGROUND

Little is known about infection risk in multiple sclerosis (MS).

OBJECTIVE

We examined infection-related health care utilization in people with and without MS.

METHODS

Using population-based health administrative data from British Columbia, Canada, people with MS were followed from their first demyelinating claim (1996-2013) until death, emigration, or study end (2013). Infection-related hospital, physician, and prescription data of MS cases were compared with sex-, age-, and geographically matched controls using adjusted regression models. Sex and age differences (18-39, 40-49, 50-59, 60+ years) were explored.

RESULTS

Relative to 35,837 controls, 7179 MS cases were over twice as likely to be hospitalized for infection (adjusted odds ratio: 2.39; 95% confidence interval (CI): 2.16-2.65), had 41% more physician visits (adjusted rate ratio (aRR): 1.41; 95% CI: 1.36-1.47), and filled 57% more infection-related prescriptions (aRR: 1.57; 95% CI: 1.49-1.65). Utilization was disproportionately higher in MS men than women and was elevated across all ages. MS cases had nearly twice as many physician visits and two to three times more hospitalizations for pneumonia, urinary system infections, and skin infections (aRRs ranged from 1.6 to 3.3) and over twice as many hospitalizations for intestinal infections (aRR = 2.6) and sepsis (aRR = 2.2).

CONCLUSION

Infection-related health care utilization was increased in people with MS across all age groups, with a higher burden for men.

Physical comorbidities increase the risk of psychiatric comorbidity in multiple sclerosis

BACKGROUND

Risk factors for psychiatric comorbidity in multiple sclerosis (MS) are poorly understood.

OBJECTIVE

We evaluated the association between physical comorbidity and incident depression, anxiety disorder, and bipolar disorder in a MS population relative to a matched general population cohort.

METHODS

Using population-based administrative data from Alberta, Canada we identified 9624 persons with MS, and 41,194 matches. Using validated case definitions, we estimated the incidence of depression, anxiety disorder, and bipolar disorder, and their association with physical comorbidities using Cox regression, adjusting for age, sex, socioeconomic status, and index year.

RESULTS

In both populations, men had a lower risk of depression and anxiety disorders than women, as did individuals who were ≥45 years versus <45 years at the index date. The risk of bipolar disorder declined with increasing age. The risks of incident depression (HR 1.92; 1.82-2.04), anxiety disorders (HR 1.52; 1.42-1.63), and bipolar disorder (HR 2.67; 2.29-3.11) were higher in the MS population than the matched population. These associations persisted essentially unchanged after adjustment for covariates including physical comorbidities. Multiple physical comorbidities were associated with psychiatric disorders in both populations.

CONCLUSION

Persons with MS are at increased risk of psychiatric comorbidity generally, and some physical comorbidities are associated with additional risk.

Network analysis of genes and their association with diseases

A plethora of network-based approaches within the Systems Biology universe have been applied, to date, to investigate the underlying molecular mechanisms of various human diseases. In the present study, we perform a bipartite, topological and clustering graph analysis in order to gain a better understanding of the relationships between human genetic diseases and the relationships between the genes that are implicated in them. For this purpose, disease-disease and gene-gene networks were constructed from combined gene-disease association networks. The latter, were created by collecting and integrating data from three diverse resources, each one with different content covering from rare monogenic disorders to common complex diseases. This data pluralism enabled us to uncover important associations between diseases with unrelated phenotypic manifestations but with common genetic origin. For our analysis, the topological attributes and the functional implications of the individual networks were taken into account and are shortly discussed. We believe that some observations of this study could advance our understanding regarding the etiology of a disease with distinct pathological manifestations, and simultaneously provide the springboard for the development of preventive and therapeutic strategies and its underlying genetic mechanisms.

Sex differences in comorbidity at diagnosis of multiple sclerosis: A population-based study

Objective:

To determine the prevalence of comorbidity in the multiple sclerosis (MS) population at the time of MS diagnosis. We also compared the prevalence of comorbidity in the MS population to that in a matched cohort from the general population.

Methods:

Using population-based administrative health data from 4 Canadian provinces, we identified 23,382 incident MS cases and 116,638 age-, sex-, and geographically matched controls. We estimated the prevalence of hypertension, diabetes, hyperlipidemia, heart disease, chronic lung disease, epilepsy, fibromyalgia, inflammatory bowel disease, depression, anxiety, bipolar disorder, and schizophrenia at MS diagnosis using validated case definitions. We compared the populations using rate ratios.

Results:

Of the MS cases, 16,803 (71.9%) were female. The most prevalent comorbidity was depression (19.1%). Compared to the matched population, all comorbidities except hyperlipidemia were more common in the MS population. Relative to the matched populations, the prevalence of hypertension was 16% higher for women with MS and 48% higher for men with MS, thus there was a disproportionately higher prevalence of hypertension in men with MS than women. Men with MS also had a disproportionately higher prevalence than women with MS for diabetes, epilepsy, depression, and anxiety.

Conclusions:

Comorbidity is more common than expected in MS, even around the time of diagnosis. The prevalence of psychiatric comorbidity is particularly high and highlights the need for clinical attention to this issue. The observed sex-specific differences in the burden of comorbidity in MS, which differ from those in the matched population, warrant further investigation.

Differing trends in the incidence of vascular comorbidity in MS and the general population

BACKGROUND

Although the adverse effects of vascular comorbidities are increasingly recognized in multiple sclerosis (MS), the epidemiology of these conditions remains poorly understood.

METHODS

Using population-based administrative data, we identified 44,452 Canadians with MS and 220,849 age-, sex- and geographically matched controls. We applied validated definitions to estimate the incidence of diabetes, hypertension, hyperlipidemia, and ischemic heart disease (IHD) from 1995 to 2005.

RESULTS

Of the MS cases, 31,757 (71.4%) were in female participants, with a mean (SD) age at the index date of 43.8 (13.7) years. Over time, the age-standardized incidence of diabetes rose more in the MS population (incidence rate ratio [IRR] per year 1.06; 95% confidence interval [CI] 1.03-1.08) than in the matched population (IRR per year 1.02; 95% CI 1.01-1.03). Temporal trends in the age-standardized incidence of hyperlipidemia, hypertension, and IHD were similar in both populations. Among those aged 20-44 years, the incidence of IHD was higher in the MS population (IRR 1.59; 95% CI 1.19-2.11). The increased incidence of IHD in the MS population was attenuated among those aged 60 years and older (IRR 1.01; 95% CI 0.97-1.06).

CONCLUSIONS

The incidence rates of diabetes, hypertension, and hyperlipidemia are rising within the MS population. Programs to systematically prevent and treat these conditions are needed.

Examining the effects of comorbidities on disease-modifying therapy use in multiple sclerosis

OBJECTIVE

Comorbidities are common in multiple sclerosis (MS) and adversely affect health outcomes. However, the effect of comorbidity on treatment decisions in MS remains unknown. We aimed to examine the effects of comorbidity on initiation of injectable disease-modifying therapies (DMTs) and on the choice of the initial DMT in MS.

METHODS

We conducted a retrospective observational analysis using population-based health administrative and linked clinical databases in 3 Canadian provinces. MS cases were defined as any individual with ≥3 diagnostic codes for MS. Cohort entry (index date) was the first recorded demyelinating disease-related claim. The outcomes included choice of initial first-line DMTs and time to initiating a DMT. Logistic and Cox regression models were used to examine the association between comorbidity status and study outcomes, adjusting for sex, age, year of index date, and socioeconomic status. Meta-analysis was used to estimate overall effects across the 3 provinces.

RESULTS

We identified 10,698 persons with incident MS, half of whom had ≥1 comorbidities. As the total number of comorbidities increased, the likelihood of initiating a DMT decreased. Comorbid anxiety and ischemic heart disease were associated with reduced initiation of a DMT. However, patients with depression were 13% more likely to initiate a DMT compared to those without depression at the index date (adjusted hazard ratio 1.13; 95% confidence interval 1.00-1.27).

CONCLUSIONS

Comorbidities are associated with treatment decisions regarding DMTs in MS. A better understanding of the effects of comorbidity on effectiveness and safety of DMTs is needed.

Effect of comorbidity on mortality in multiple sclerosis

Objective:

We aimed to compare survival in the multiple sclerosis (MS) population with a matched cohort from the general population, and to evaluate the association of comorbidity with survival in both populations.

Methods:

Using population-based administrative data, we identified 5,797 persons with MS and 28,807 controls matched on sex, year of birth, and region. We estimated annual mortality rates. Using Cox proportional hazards regression, we evaluated the association between comorbidity status and mortality, stratifying by birth cohort, and adjusting for sex, socioeconomic status, and region. We compared causes of death between populations.

Results:

Median survival from birth in the MS population was 75.9 years vs 83.4 years in the matched population. MS was associated with a 2-fold increased risk of death (adjusted hazard ratio 2.40; 95% confidence interval: 2.24–2.58). Several comorbidities were associated with increased hazard of death in both populations, including diabetes, ischemic heart disease, depression, anxiety, and chronic lung disease. The magnitude of the associations of mortality with chronic lung disease, diabetes, hypertension, and ischemic heart disease was lower in the MS population than the matched population. The most common causes of death in the MS population were diseases of the nervous system and diseases of the circulatory system. Mortality rates due to infectious diseases and diseases of the respiratory system were higher in the MS population.

Conclusion:

In the MS population, survival remained shorter than expected. Within the MS population, comorbidity was associated with increased mortality risk. However, comorbidity did not preferentially increase mortality risk in the MS population as compared with controls.

A systematic review of the incidence and prevalence of comorbidity in multiple sclerosis: overview

Background:

Comorbidity is an area of increasing interest in multiple sclerosis (MS).

Objective:

The objective of this review is to estimate the incidence and prevalence of comorbidity in people with MS and assess the quality of included studies.

Methods:

We searched the PubMed, SCOPUS, EMBASE and Web of Knowledge databases, conference proceedings, and reference lists of retrieved articles. Two reviewers independently screened abstracts. One reviewer abstracted data using a standardized form and the abstraction was verified by a second reviewer. We assessed study quality using a standardized approach. We quantitatively assessed population-based studies using the I² statistic, and conducted random-effects meta-analyses.

Results:

We included 249 articles. Study designs were variable with respect to source populations, case definitions, methods of ascertainment and approaches to reporting findings. Prevalence was reported more frequently than incidence; estimates for prevalence and incidence varied substantially for all conditions. Heterogeneity was high.

Conclusion:

This review highlights substantial gaps in the epidemiological knowledge of comorbidity in MS worldwide. Little is known about comorbidity in Central or South America, Asia or Africa. Findings in North America and Europe are inconsistent. Future studies should report age-, sex- and ethnicity-specific estimates of incidence and prevalence, and standardize findings to a common population.

Comorbidity increases the risk of hospitalizations in multiple sclerosis

OBJECTIVE

We aimed to evaluate the association between comorbidity and rates of hospitalization in the multiple sclerosis (MS) population as compared to a matched cohort from the general population.

METHODS

Using population-based administrative data from the Canadian province of Manitoba, we identified 4,875 persons with MS and a matched general population cohort of 24,533 persons. We identified all acute care hospitalizations in the period 2007-2011. Using general linear models, we evaluated the association between comorbidity status and hospitalization rates (all-cause, non-MS-related, MS-related) in the 2 populations, adjusting for age, sex, and socioeconomic status.

RESULTS

Comorbidity was common in both cohorts. Over the 5-year study period, the MS population had a 1.5-fold higher hospitalization rate (adjusted rate ratio [aRR] 1.56; 95% confidence interval [CI] 1.44-1.68) than the matched population. Any comorbidity was associated with a 2-fold increased risk of non-MS-related hospitalization rates (aRR 2.21; 95% CI 1.73-2.82) in the MS population, but a nearly 4-fold increase in hospitalization rates in the matched population (aRR 3.85; 95% CI 3.40-4.35). Comorbidity was not associated with rates of hospitalization for MS-related reasons, regardless of how comorbidity status was defined.

CONCLUSIONS

In the MS population, comorbidity is associated with an increased risk of all-cause hospitalizations, suggesting that the prevention and management of comorbidity may reduce hospitalizations.

A systematic review of the incidence and prevalence of cardiac, cerebrovascular, and peripheral vascular disease in multiple sclerosis

BACKGROUND

Findings regarding the prevalence of vascular comorbidities in multiple sclerosis (MS) are conflicting.

OBJECTIVE

The objective of this review is to estimate the incidence and prevalence of vascular comorbidities and predisposing comorbidities in persons with MS and to assess the quality of the included studies.

METHODS

The PubMed, EMBASE, SCOPUS and Web of Knowledge databases, conference proceedings, and reference lists of retrieved articles were searched. One reviewer abstracted data using a standardized data collection form, while the second reviewer verified the abstraction. Included studies were assessed qualitatively. Quantitatively, we assessed studies using the I² statistic, and conducted meta-analyses for population-based studies only.

RESULTS

The prevalence of hypertension and hyperlipidemia exceeded 10% in the MS population and increased with age. While the prevalence of ischemic heart disease, congestive heart failure, and stroke were less than 5% overall, the prevalence of these conditions exceeded expectations when compared to the general population. Cardiac valvular disease, however, affected the MS population less often than expected. Problems with study quality were common.

CONCLUSION

Despite the relatively high prevalence of some vascular comorbidities in the MS population, important gaps exist in our understanding of their epidemiology. Most of our knowledge is based on studies conducted in a small number of regions.

Vascular comorbidities in the onset and progression of multiple sclerosis

Vascular comorbidities are common in the general population and are associated with adverse health outcomes. In people with multiple sclerosis (MS), an increasing amount of evidence suggests that vascular comorbidities are also common, but an association with MS risk and disability has not been conclusively established. This review aims to critically examine published data on the relationship between vascular comorbidities (including vascular risk factors) and MS. The evidence suggests an increased risk of MS in people with a high BMI during childhood or adolescence but not adulthood. People with established MS appear to have a slightly increased risk of cardiovascular disease and a greater proportion of people with MS die from cardiovascular disease, which has important implications for clinicians trying to identify risk factors for cardiovascular disease and reviewing treatment options. In relation to whether vascular comorbidities influence MS clinical disability or other aspects of the disease course, the key finding was that having type-2-diabetes, hypertension, dyslipidaemia or peripheral vascular disease at any point in the disease course may be associated with a greater progression in disability. Additionally, a negative effect of high cholesterol and triglycerides and a positive effect of higher HDL (high density lipoprotein) levels on acute inflammatory activity were observed on magnetic resonance imaging. The results of the published clinical trials of statins as an intervention in MS were however conflicting and care needs to be taken when treating people with MS with statins. Taken together, the literature seems to indicate a potential association of vascular comorbidities with MS risk and disability, but the number of prospective studies was sparse, thus precluding ascription of causality. We therefore recommend that future studies of the frequency and effects of vascular comorbidities on MS risk and disability should be prospective and objective where relevant.

Dramatically changing rates and reasons for hospitalization in multiple sclerosis

OBJECTIVE

We aimed to describe hospitalizations in the multiple sclerosis (MS) population, and to evaluate temporal trends in hospitalizations in the MS population compared to the general population.

METHODS

Using population-based administrative data, we identified 5,797 persons with MS and a matched general population cohort of 28,769 persons. Using general linear models, we evaluated temporal trends in hospitalization rates and length of stay in the 2 populations over the period 1984-2011.

RESULTS

In 1984 the hospitalization rate was 35 per 100 person-years in the MS population and 10.5 in the matched population (relative risk [RR] 3.33; 95% confidence interval: 1.67-6.64). Over the study period hospitalizations declined 75% in the MS population but only 41% in the matched population. The proportion of hospitalizations due to MS declined substantially from 43.4% in 1984 to 7.8% in 2011. The 3 most common non-MS-related reasons for admission in the MS population were diseases of the digestive, genitourinary, and circulatory systems. Admissions for bacterial pneumonia, influenza, urinary tract infections, and pressure ulcers occurred more often in the MS population than in the general population, while admissions for circulatory system disease and neoplasms occurred less often. Older age, male sex, and lower socioeconomic status were associated with increased hospitalization rates for non-MS-related reasons.

CONCLUSIONS

Although hospitalization rates have declined dramatically in the MS population over the last quarter century, they remain higher than in the general population. Admissions for MS-related reasons now constitute only a small proportion of the reasons for hospitalization.

Intensive care unit admission in multiple sclerosis: increased incidence and increased mortality

OBJECTIVE

To compare the incidence of, and mortality after, intensive care unit (ICU) admission as well as the characteristics of critical illness in the multiple sclerosis (MS) population vs the general population.

METHODS

We used population-based administrative data from the Canadian province of Manitoba for the period 1984 to 2010 and clinical data from 93% of admissions to provincial high-intensity adult ICUs. We identified 5,035 prevalent cases of MS and a cohort from the general population matched 5:1 on age, sex, and region of residence. We compared these populations using incidence rates and multivariable regression models adjusting for age, sex, comorbidity, and socioeconomic status.

RESULTS

From January 2000 to October 2009, the age- and sex-standardized annual incidence of ICU admission among prevalent cohorts was 0.51% to 1.07% in the MS population and 0.34% to 0.51% in matched controls. The adjusted risk of ICU admission was higher for the MS population (hazard ratio 1.45; 95% confidence interval [CI] 1.19-1.75) than for matched controls. The MS population was more likely to be admitted for infection than the matched controls (odds ratio 1.82; 95% CI 1.10-1.32). Compared with the matched controls admitted to ICUs, 1-year mortality was higher in the MS population (relative risk 2.06; 95% CI 1.32-3.07) and was particularly elevated in patients with MS who were younger than 40 years (relative risk 3.77; 95% CI 1.45-8.11). Causes of death were MS (9.3%), infections (37.0%), and other causes (52.9%).

CONCLUSIONS

Compared with the general population, the risk of ICU admission is higher in MS, and 1-year mortality after admission is higher. Greater attention to preventing infection and managing comorbidity is needed in the MS population.