The effect of anti-TNF on renal function in patients with ankylosing spondylitis: a prospective cohort study

BACKGROUND: Biologicals, such as anti-tumor necrosis factor (anti-TNF), reduce cardiovascular disease (CVD) in patients with inflammatory rheumatic diseases. Impaired renal function is a known predictor of CVD and elevated in ankylosing spondylitis (AS). OBJECTIVE: To assess the effect of anti-TNF on renal function in patients with AS and whether anti-TNF use is safe in AS patients with pre-existing risk factors for renal decline. METHOD: Biological-naïve consecutive AS patients treated with etanercept or adalimumab were prospectively followed from 2005 to 2014. Renal function was determined by calculation of the estimated glomerular filtration rate (eGFR), estimated with the abbreviated modification of diet in renal disease (MDRD) formula. The effect of anti-TNF on eGFR was analyzed using mixed model analysis. RESULTS: 211 AS patients were followed for a median of 156 (36–286) weeks. Overall mixed model analyses showed a significant decrease of eGFR over time (β = − 0.040, p = 0.000), although this association did not remain significant after adjustment for responding to anti-TNF, alcohol use, disease duration, body mass index (BMI), C-reactive protein (CRP), and disease activity (β = − 0.018, p = 0.094). However, patients with pre-existing risk factors for renal decline did have a significant change in eGFR over time (β = − 0.029, p = 0.006). CONCLUSIONS: We found a significant change in eGFR over time, although this small decrease was not clinically relevant. This study further demonstrates that anti-TNF does not affect renal function in AS patients with and without existing risk factors for renal decline, which means that use of anti-TNF is safe concerning renal function in patients with AS.