Objective. Analysis of the renal status in patients with axial spondyloarthritis (SpA), taking non-steroidal anti-inflammatory drugs (NSAIDs) continuously for 24 months.
Material and methods. 12 and 24 months from the start of continuous administration of NSAIDs, the glomerular filtration rate (GFR), urine α1-microglobulin and albumin levels equivalent to 1 g of urinary creatinine were determined in 36 patients with SpA without an initial renal failure.
Results. 24 months after start of study, the average GFR was 107.0 [93.0; 125.0] ml/min/1.73 m2, urine α1-microglobulin was 24.78 [19.87; 34.73] mg/g (P≥0.05 for differences with baseline value) against the background of continuous use of NSAIDs. A marked increase in the urine albumin level to 44.24 [28.46; 85.96] mg/g (P=0.035 compared with baseline level and with urine albumin levels after 12 months of treatment). After 24 months of follow-up, the deviation in three indicators (GFR, microglobulin, urine albumin level) was revealed in 2 (5.6%) patients with SpA. An increase in the urine albumin or α1-microglobulin level or a decrease in GFR of less than 90 ml/min/ 1.73 m2 was detected in 10 (27.8%) patients. 7 (19.4%) patients showed abnormalities in two markers of renal damage. Overall, kidney damage was recorded in 18 (50%) patients with SpA. In all patients, GFR corresponded to chronic kidney disease stage 1–2.
Conclusion. Against the background of continuous use of NSAIDs for 24 months, 18 (50%) patients with SpA showed some changes in the renal status. Kidney damage from all established cases was more common in patients taking diclofenac sodium.

Keywords: the safety of NSAIDs, axial spondyloarthritis, renal safety, ankylosing spondylitis, nonsteroidal anti-inflammatory drugs