Are infection risks associated with tumor-necrosis factor inhibitors decreasing?

This study assessed the risk of serious infection during treatment with tumor-necrosis factor inhibitors in rheumatoid arthritis patients.

Over the past decade, tumor necrosis factor (TNF) inhibitors have become increasingly popular treatments for rheumatoid arthritis. TNF inhibitors, also known as biologics, block the activity of tumor necrosis factor, a protein that is a cause of inflammation. New TNF inhibitors continue to be developed, and the safety and efficacy profiles of these drugs are influenced by the characteristics of the patients selected to receive them. A drug which is safe for one patient may lead to serious infection in another. The safety profile of a treatment can help a physician choose the proper therapy for a patient, thereby lowering the risk of serious infection or other negative effects. The current study examined whether improved safety profiles for TNF inhibitors have decreased the risks of serious infection in rheumatoid arthritis patients.

This study compared two groups of patients: 716 who began treatment with TNF inhibitors between 2005 and 2007, and 353 who started therapy between 2008 and 2011. Both groups received the TNF inhibitors infliximab (Remicade) and etanercept (Enbrel), while the 2008-2011 group also received adalimumab (Humira). Patients were followed for an average of 1 year following the start of treatment.

103 serious adverse events (any untoward medical occurrence that may not necessarily be associated with the drug) and 42 serious infections occurred in the 2005 group, compared to 41 adverse events and 9 serious infections in the 2008 group. Serious infections were predominantly respiratory tract infections. Patients in the 2008 group had a 57% lower risk of serious infections.

Those who presented with comorbidities (the presence of one or more additional diseases) including lung, liver, kidney diseases and diabetes were also 2.23 times more likely to experience infection. Each increasing decade of age was associated with a 76% increased risk of serious infection.

80.9% of the patients in the 2008 group achieved low disease activity, as measured by the Disease Active Score 28 (a measure of rheumatoid arthritis activity in 28 joints), compared to 68.7% of patients in the 2005 group. A higher proportion of the 2008 group discontinued TNF inhibitors due to achieving good disease control.

This study concluded that improved safety profiles for tumor necrosis factor inhibitors have decreased the risks of serious infections and adverse events in rheumatoid arthritis patients.