Effects of biological and targeted synthetic DMARDs on bone loss in rheumatoid arthritis

Bone loss is a typical consequence of Rheumatoid Arthritis (RA). It occurs not only locally, affecting the inflamed joints (erosions), but also systemically, leading to osteopenia and/or overt osteoporosis, with increased risk of fragility fractures. This complication, often underestimated, can worsen the burden of disability in RA patients. Moreover, systemic and local bone loss are closely intertwined as osteoporosis per se can facilitate the development of erosions. A fundamental role in this process is played by the osteoimmunologic dysregulation typical of RA and other chronic inflammatory conditions. The poor response to the DMARDs, in terms of progression of bone erosions, might depend on the concomitant osteoporosis and on other determinants of bone loss. Thus, we need a deeper investigation in RA patients of bone health and effects of DMARDs on it and, eventually, a specific anti-osteoporotic treatment, other than DMARDs, for the prevention of both fragility fractures and bone erosions. The present review summarizes the most relevant evidence on systemic bone loss of biological and targeted synthetic DMARDs.