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Résumé :
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[BDSP. Notice produite par INIST-CNRS pR0xrJA7. Diffusion soumise à autorisation]. Longitudinal observational data are required to assess the association between exposure to bêta-interferon medications and disease progression among relapsing-remitting multiple sclerosis (MS) patients in the "real-world" clinical practice setting. Marginal structural Cox models (MSCMs) can provide distinct advantages over traditional approaches by allowing adjustment for time-varying confounders such as MS relapses, as well as baseline characteristics, through the use of inverse probability weighting. We assessed the suitability of MSCMs to analyze data from a large cohort of 1,697 relapsing-remitting MS patients in British Columbia, Canada (1995-2008). In the context of this observational study, which spanned more than a decade and involved patients with a chronic yet fluctuating disease, the recently proposed "normalized stabilized" weights were found to be the most appropriate choice of weights. Using this model, no association between bêta-interferon exposure and the hazard of disability progression was found (hazard ratio=1.36,95% confidence interval : 0.95,1.94). For sensitivity analyses, truncated normalized unstabilized weights were used in additional MSCMs and to construct inverse probability weight-adjusted survival curves ; the findings did not change. Additionally, qualitatively similar conclusions from approximation approaches to the weighted Cox model (i.e., MSCM) extend confidence in the findings.
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