What is the impact of biologic therapies on common co-morbidities in patients with rheumatoid arthritis?

Biologic therapies have revolutionised disease control in patients with rheumatoid arthritis. Theoretically, they have the potential to influence co-morbid disease associated with RA through better control of systemic inflammation. Conversely, co-morbidity may occur as an adverse effect of the drugs. The latest evidence from observational data shows an increased risk of infection in the first 6 month of treatment with tumour necrosis factor inhibitor (TNFi) therapies and potentially other biologic therapies. Rates of infection after the first 6 months decrease and become comparable to patients with RA treated with conventional synthetic disease modifying drugs (csDMARDs). TNFi also appear to reduce the risk of cardiovascular disease in these patients, in particular ischaemic heart disease. TNFi treatment may be associated with a small increase in the risk of developing squamous cell carcinoma of the skin; in terms of other cancers rates appears to be no different to those seen in patients treated with csDMARDs. There is a paucity of data on the impact of other biologic therapies and the effect of all biologic therapies on other common co-morbidities.