Prevalence, Risk Factors of Renal Impairment Evaluated in Spondyloarthritis

In patients with spondyloarthritis (SpA), renal impairment is associated with age, HLA-B27 positivity, and inflammation, but not with disease severity or cardiovascular (CV) risk factors, according to data from the Assessment of Spondyloarthritis International Society-Comorbidities in Spondyloarthritis (ASAS-COMOSPA) study published in The Journal of Rheumatology.

The investigators sought to evaluate the prevalence of renal dysfunction in patients with SpA using data from the ASAS-COMOSPA study, which explored comorbidities in individuals with SpA. Renal function was assessed according to estimated glomerular filtration rate (eGFR), which was measured using the Modification of Diet in Renal Disease (MDRD) equation. Features of SpA and risk factors associated with renal impairment were gathered. Researchers also evaluated use of nonsteroidal anti-inflammatory drugs (NSAIDs) based on intake over the previous 3 months.

Overall, 3984 patients with SpA were included in the study; 52.6% had data available to allow eGFR calculation with the MDRD equation. The mean patient age in the study population was 45.3±13.7 years, and the majority (63.5%) of the patients were men. Mean SpA duration was 8.6±9.0 years, HLA-B27 was positive in 73.1% of patients, and the average Bath Ankylosing Spondylitis Activity Index (BASDAI) score was 3.6.

A total of 153 patients exhibited an eGFR <60 mL/min/1.73 m². Based on univariate analysis, renal impairment was significantly associated with the following parameters: age (P <.001), HLA-B27 positivity (P =.003), disease activity scores (BASDAI, P =.001; Ankylosing Spondylitis Disease Activity Score-C-reactive protein[CRP], P <.001), functional variables (Bath Ankylosing Spondylitis Functional Index, P <.001), inflammatory biomarkers (erythrocyte and CRP, P <.001 for both), and NSAID intake since disease onset (P =.008). After univariate analysis, several CV risk factors were found to be associated with renal impairment, including history of hypertension (P <.001), systolic blood pressure (P =.009), diabetes (P =.005), and Framingham risk score (P <.001). There was no association reported with disease duration, disease severity, or ASAS-NSAID score.

In multivariate analysis, age (45 to 59 years: odds ratio [OR], 1.9; age >60 years: OR, 6.2), HLA-B27 positivity (OR, 0.51), and CRP level (OR, 1.3) all remained significantly associated with eGFR <60 mL/min/1.73 m².

The investigators concluded that in patients with SpA, renal dysfunction is linked to age, HLA-27 positivity, and inflammation, but not to CV risk factors, disease severity, or NSAID intake. Systematic assessment of eGFR is needed in patients with SpA, specifically in those who are treated with nephrotoxic therapies.

Reference

Couderc M, Pereira B, Molto A, Tiple A, Soubrier M, Dougados M. The prevalence of renal impairment in patients with spondyloarthritis: results from the international ASAS-COMOSPA study [published online April 15, 2018].  J Rheumatol. doi: 10.3899/jrheum.170133