Causal and Associational Language in Observational Health Research: A Systematic Evaluation.

We estimated the degree to which language used in the high-profile medical/public health/epidemiology literature implied causality using language linking exposures to outcomes and action recommendations; examined disconnects between language and recommendations; identified the most common linking phrases; and estimated how strongly linking phrases imply causality. We searched for and screened 1,170 articles from 18 high-profile journals (65 per journal) published from 2010-2019. Based on written framing and systematic guidance, 3 reviewers rated the degree of causality implied in abstracts and full text for exposure/outcome linking language and action recommendations. Reviewers rated the causal implication of exposure/outcome linking language as none (no causal implication) in 13.8%, weak in 34.2%, moderate in 33.2%, and strong in 18.7% of abstracts. The implied causality of action recommendations was higher than the implied causality of linking sentences for 44.5% or commensurate for 40.3% of articles. The most common linking word in abstracts was "associate" (45.7%). Reviewers' ratings of linking word roots were highly heterogeneous; over half of reviewers rated "association" as having at least some causal implication. This research undercuts the assumption that avoiding "causal" words leads to clarity of interpretation in medical research.

Safety liver profile of teriflunomide versus interferon ß in multiple sclerosis: Systematic review and indirect comparison meta-analysis.

OBJECTIVES: To compare the liver safety profile of interferon ß (IFN ß) and teriflunomide in patients with multiple sclerosis. METHODS: A network meta-analysis was carried out following the Cochrane Collaboration methodology. All trials comparing all types of IFN ß with teriflunomide, or disease-modifying drugs, or placebo in RRMS were included. An indirect comparison network meta-analysis within a Bayesian framework with STATA (version 13.0) was done for this study. RESULTS: The database searches yielded 284 titles, with 15 records as duplicates. One study was identified by manually searching. Thirteen articles were included in the systematic review. Twelve studies compared IFN ß (4203 patients) vs another DMT. Four studies evaluated the effectiveness and safety of teriflunomide (906 patients) vs another DMT. Six studies reported drug-induced liver injury as per the Hy's Law. However, only one study had a direct comparison and reported no cases of liver toxicity in either group, so it was not possible to estimate the OR. The indirect comparisons metanalysis shows that there was no statistically-significant difference between teriflunomide and IFN ß (OR 1.09, 95% CI 0.02-2.16). CONCLUSIONS: There were no significant difference when comparing IFN ß and teriflunomide in terms of liver failure or elevation of transaminases.