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

Abstract

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.

Multiple sclerosis in Canada 2011 to 2031: results of a microsimulation modelling study of epidemiological and economic impacts

“…33,34 Such conditions may be precursors to or related sequelae of MS, or may be present independent of MS. Individuals both with and without MS may experience some of these conditions.…”

Effect of Comorbidities on Outcomes of Neurorehabilitation Interventions in Multiple Sclerosis

“…Of concern is the finding that most of the commonly excluded comorbidities represent some of the most prevalent ones experienced by people with MS (eg, cognitive and psychiatric disorders and cardiovascular diseases). 6 Furthermore, in some studies, the descriptions provided for excluded comorbidities were vague, for example, "other illnesses that may affect motor function." 16 Most studies did not provide any information about measurement tools and cutoff scores used to determine eligibility, particularly for cognitive impairment.…”

“…However, neither of these studies examined the possible mediating or moderating effect of comorbidities on intervention outcomes. Recent systematic reviews have identified common comorbidities experienced by people with MS. 6 Together with the gaps identified by the present review, the body of evidence suggests that MS neurorehabilitation researchers should prioritize the inclusion of participants with comorbidities such as cognitive impairment and psychiatric and cardiovascular conditions. This work also suggests that investigating the effect of these comorbidities on intervention outcomes is clearly warranted.…”

“…Mental conditions, such as depression and anxiety, are also commonly reported. 6 Despite advances in disease-modifying therapies that may reduce disease progression, the residual level of disability remains unchanged. 7 Consequently, neurorehabilitation interventions are needed to manage the consequences of MS. 8 For the purposes of this study, we defined neurorehabilitation interventions as any treatment activities or services aimed at reducing the effect of disability resulting from MS using the principles of neuroplasticity.…”

Managing the complexity of multiple sclerosis

“…Mortality from infectious diseases and diseases of the respiratory system was higher in the MS population than in the control population. These findings extend the results of previous studies that reported an effect of comorbidity on the diagnosis of and disability in MS 9 , suggesting that treatment and prevention of comorbidities improves survival in MS. Future research will fill important gaps in our knowledge about the worldwide epidemiology of comorbidity in MS 10 .…”