Background Over the past years, many new biologics have been introduced for the treatment of RA. In clinical practice, treatment guidelines and perceived or established differences between available biologics lead to a non-random allocation of treatment, the magnitude of which is seldom quantified but essential for a correct understanding of their comparative effectiveness and safety. In Sweden, national treatment guidelines for RA suggest the use of TNF inhibitors (with no inter-drug preference) as first biologic, but the use of non-anti TNF biologics (with no inter-drug preference) in case of contra-indications or non-response to TNF-inhibitors.
Objectives To assess differences in baseline characteristics across biologics.
Methods Data on biological treatment, RA characteristics, demographics, and comorbidities among RA patients initiating biological therapies were identified in the nationwide Swedish Biologics Register (ARTIS) 2006-2011 (estimated coverage around 90%, and through linkage to the nationwide and virtually complete Swedish Patient Register. Initiators of biological therapies were stratified by type of biologic and by previous use of any biologic.
Results There were only moderate differences with respect to demographics and RA characteristics (Table). These differences were larger between drugs than between initiators of a given drug as first vs. later biologic. In contrast, we noted large differences in the prevalence of comorbidities across different biologics, with higher load of co-morbidities among patients initiating non-antiTNF biologics as their first biologic.
Conclusions We observed clear channeling, notably a higher prevalence of comorbidities in patients for whom non-anti-TNF biologics were chosen. There were smaller differences between initiators of older and newer anti-TNF drugs. We speculate that the observed channeling is related to perceived safety and effectiveness. Studies of comparative effectiveness and safety of different biologics must factor in, and be interpreted in light of, this channeling which is as pronounced among subsets of initiators of a particular biologic as between different biologics.
Acknowledgements ARTIS has agreements with Abbott, BMS, Merck, Sobi, AstraZeneca, Pfizer, and Roche
Disclosure of Interest: None Declared