Infection Rates with Rheumatoid Arthritis Medications – TNF Drugs

What are TNF Blockers?

The five medications below are often called called ‘TNF-blockers’ and are used for rheumatoid arthritis and certain other arthritic diseases (TNF stands for tumor necrosis factor, a protein – we all have naturally in our systems, but if you have rheumatoid arthritis, it makes things worse). These medicines may be used if another medicine, such as methotrexate alone fails to control the arthritic inflammation. Although generally very safe when they are used correctly, they slightly lower the immune defense system. Infections are one of the most frequent side effects of these medicines.

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They are Cimzia, Enbrel, Humira, Remicade, and Simponi. (Simponi is called ‘Simponi Aria‘ when given in the vein).

What types of infections?

The serious types of infections are usually pneumonia, sinusitis, bronchitis, sore throat, cellulitis (skin infection), kidney or bladder infections, and sepsis (blood infection).

Infection rates below are simplified for clarity, and are taken from the manufacturers’ official published drug information (prescribing information). As you can see, each company reports infections differently, making it difficult to exactly compare apples to apples, but the numbers below will provide a general feeling for how risky (or not) these medications are for the development of infections. As a group, it seems the risk is about 5 out of 100 treated patients each year will develop a serious infection; usually these are infections which could be life or limb threatening if not treated aggressively with antibiotics – often in the hospital.

Five Main TNFs – for now!

Cimzia – In all patient in study populations combined before the drug was approved, the most common reported infections were upper respiratory infections (18%) and urinary tract infections (8%). (For some reason they only reported infections that happened in more than 8% of people being studied). When compared with patients not taking Cimzia, infection of the nose and throat (nasopharyngitis) 5%, placebo 1%, upper respiratory infection Cimzia 6%, placebo 2%, and acute bronchitis Cimzia 3%, placebo 1%. (I’m not certain I know the difference between upper respiratory infection and nasopharyngitis however – they refer to the same area.)

Enbrel – serious infections overall 1.4% in treated groups using Enbrel (with or without methotrexate).

Humira – In their studies, if 100 patients took Humira for a year, there were 4.6 serious infections, versus 3.1 infections in patients not receiving the medication (placebo), for any condition that Humira is approved.

Remicade – 5.3% of patients who received Remicade serious infections as compared to 3.4% of placebo patients

Simponi – Using patient years,  if 100 patients took Simponi for a year for rheumatoid arthritis, there would be predicted 5.7 serious infections, versus 4.2 infections in patients not receiving the medication.

High Risk Infections

In all the the ‘TNF blockers’ patients at higher risk (elderly or those with diminished immune systems or a tendency for infections) are at higher risk for infections as they normally would not have to worry as much about due to bacterial, tuberculosis or other tuberculosis-like bacteria, invasive fungus, virus, parasite, valley fever or other opportunistic pathogens including certain mold-like and yeast-like diseases. These are usually less than 0.1% however, and low risk.

About Doug Roberts MD

Board certified practicing rheumatologist and founder of
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