Background Patients with rheumatoid arthritis (RA) are more likely to develop chronic kidney disease (CKD) than those without it over time [1]. CKD is one of the major limiting factors for the use of RA-related drugs [2], and has some influence on the clinical course of RA.

Objectives To evaluate the impact of CKD on the treatment and complications of Japanese patients with RA.

Methods We enrolled 300 Japanese patients with RA (245 females and 55 males; mean age 61.6±13.7 years; disease duration 11.1±9.6 years) at 4 hospitals from April 2011 to September 2011. Renal function was evaluated by the estimated glomerular filtration rate (eGFR) calculated from the Cockcroft-Gault formula modified for Japanese patients. These patients were divided into two groups by their eGFR: group A, eGFR≥60 ml/min/m², which represents normal renal function to CKD stage G1-2, and group B, eGFR<60 ml/min/m², representing CKD stage G3-5 (CKD). We investigated the treatment of RA including corticosteroid, nonsteroidal anti-inflammatory drugs (NSAIDs), methotrexate (MTX), other nonbiologic disease-modifying antirheumatic drugs (DMARDs), and biologics, the disease activity measured by Disease Activity Score (DAS) 28-CRP, and co-morbidities including hypertension, diabetes mellitus, chronic lung disease, acute myocardial infarction, extraarticular manifestations, and severe infection, which included only the prevalence of infectious events requiring hospitalizations during the 5 years before this study period. Then we analyzed the influence of CKD on these clinical parameters.

Results Group B consisted of 47 patients (15.7%). Patients in group B were significantly older (70.1±9.4 vs. 60.0±13.8 years), with longer duration of RA (14.3±10.1 vs. 10.6±9.4 years), and higher prevalence of hypertension (51.1% vs. 17.0%). The frequency of use of NSAIDs (14.9% vs. 32.0%) and dose of MTX (3.4±3.6 vs. 4.8±3.6 mg) were significantly lower in group B, but there were no differences in the frequency or dose of corticosteroid, frequency of DMARDs including MTX, or total biologics used. The prevalence of severe infectious events was significantly higher in group B than group A (25.0% vs. 10.6%). There were no significant differences between these 2 groups in disease activity or other complications. On the other hand, patients treated with biologics (biologics group) tended to have a higher prevalence of infectious events than those without them (17.6% vs. 10.4%; p=0.076). In the biologics group, in particular, patients in group B had a significantly higher prevalence of infections than those in group A (41.2% vs. 13.2%). Multivariable analysis revealed CKD to be one of the independent risk factors for infectious events in patients with biologics (β=-1.526, p=0.041).

Conclusions RA patients with CKD were older and had a longer duration of RA than those without CKD. They were administrated a lower dose of MTX, but disease activity was almost the same. They had a higher prevalence of infections, and CKD was one of the independent risk factors especially in those with biologics. Therefore, we need to pay particular attention to infections in RA patients with CKD, especially those treated with biologics.

References

1. LaTonya J. Hickson et al. Am J Kidney Dis. 2013 Oct 4. Epub ahead of print.

2. Axel J Hueber et al. Ann Rheum Dis. 2007;66:981-2.

Disclosure of Interest None declared

DOI 10.1136/annrheumdis-2014-eular.3584