4.3  bDMARDs
The risk of infection observed in RA patients treated with bDMARDs is generally considered slightly higher (from 1.5- up to 2-fold) compared with csDMARDs [27,54]. This evidence recurred in most RCTs [55] and observational registry studies [[56], [57], [58]] and was confirmed by a recent meta-analysis which showed that this risk is progressively increasing in relation to the use of bDMARDs at higher than recommended dosages [59]. Following the results of comparative metanalyses and real-life studies, abatacept is accepted as the safest bDMARD in terms of infectious risk [60,61].
Data focused on viral respiratory infections in bDMARD cohort are still very limited. The incidence of influenza-like infections observed in a cohort of 159 Italian patients treated with bDMARDs during the influenza season 2009–2010 was higher than the value reported in a wide sample of Italian population in the same period, even though no important complications or hospitalizations have been reported [62]. Overall, post-marketing experience is relatively reassuring that anti-TNF treated patients may not be at any specifically increased risk of influenza and that severe adverse outcomes, including death, do not appear to be exceedingly frequent [63].