A Systematic Review of Modifiable Risk Factors in the Progression of Multiple Sclerosis

Published in: Multiple Sclerosis Journal, Volume 23, Issue 4 (February 2017), pages 525 - 533. doi: 10.1177/1352458517690270

Posted on RAND.org on March 31, 2017

by Susanne Hempel, Glenn D. Graham, Ning Fu, Elena Estrada, Annie Chen, Isomi M. Miake-Lye, Jeremy N. V. Miles, Roberta M. Shanman, Paul G. Shekelle, Jessica M. Beroes, et al.

Read More

Access further information on this document at Multiple Sclerosis Journal

This article was published outside of RAND. The full text of the article can be found at the link above.

BACKGROUND: The presenting symptoms and rate of progression of multiple sclerosis (MS) are very heterogeneous. The diverse clinical manifestations and the clinical course of the disease may vary with modifiable risk factors. OBJECTIVE: To systematically review modifiable risk factors and exposures associated with MS progression. METHODS: We searched six databases till March 2015, reference-mined reviews, and consulted with experts (PROSPERO 2015:CRD42015016461). Two reviewers screened and extracted data. We used random meta-analysis models and Grading of Recommendations Assessment, Development, and Evaluation (GRADE) to assess the quality of evidence. RESULTS: In total, 59 studies met inclusion criteria. Lower vitamin D levels were associated with higher Expanded Disability Status Scale (EDSS) scores (r = −0.22; confidence interval (CI) = −0.32, −0.12; 11 studies; I2 = 66%), smokers had an increased risk of MS progression (hazard ratio (HR) = 1.55; CI = 1.10, 2.19; I2 = 72%; seven studies), and there was no association of MS progression with the use of epidural analgesics during childbirth delivery (three studies). There was insufficient evidence to draw conclusions for 11 risk factors due to conflicting results or use of different predictor and outcome measures. CONCLUSION: MS progression was consistently associated with low vitamin D levels, and smoking was associated with a more rapid decline in MS disability. Studies used a variety of methods, predictors, and outcomes making it difficult to draw conclusions. Future studies should focus on prospective assessments.

This report is part of the RAND Corporation External publication series. Many RAND studies are published in peer-reviewed scholarly journals, as chapters in commercial books, or as documents published by other organizations.

Our mission to help improve policy and decisionmaking through research and analysis is enabled through our core values of quality and objectivity and our unwavering commitment to the highest level of integrity and ethical behavior. To help ensure our research and analysis are rigorous, objective, and nonpartisan, we subject our research publications to a robust and exacting quality-assurance process; avoid both the appearance and reality of financial and other conflicts of interest through staff training, project screening, and a policy of mandatory disclosure; and pursue transparency in our research engagements through our commitment to the open publication of our research findings and recommendations, disclosure of the source of funding of published research, and policies to ensure intellectual independence. For more information, visit www.rand.org/about/principles.

The RAND Corporation is a nonprofit institution that helps improve policy and decisionmaking through research and analysis. RAND's publications do not necessarily reflect the opinions of its research clients and sponsors.