Chronic kidney disease in patients with psoriatic arthritis: a cohort study

Objectives Chronic kidney disease (CKD) is a comorbidity in psoriatic arthritis (PsA). We aimed to define the prevalence of CKD in patients with PsA, describe their long-term renal outcomes and identify risk factors for CKD development. Methods We included patients with PsA followed by our prospective observational cohort. We defined CKD as an estimated glomerular filtration rate (eGFR) <60 mL/min/1.73 m(2) for at least 3 months. We characterised long-term renal outcomes of CKD cases identified following clinic entry. We used time-dependent Cox regression models to identify factors associated with CKD development. Results Of 1336 patients included in the study, 123 (9.2%) had CKD. Of these, 25 (20.3%) were observed to have CKD at clinic entry and 98 (79.7%) developed CKD during follow-up at a median (IQR) of 8.2 (2.8-14.0) years from baseline. Doubling of baseline creatinine was observed in 18 of 98 (18.3%) new patients with CKD. 49 (50%) patients developed a sustained >= 40% reduction in baseline eGFR. Two patients developed eGFR <15 mL/min/1.73 m(2). In the multivariate Cox regression model adjusted for age at study entry, sex and baseline eGFR, factors independently associated with the development of CKD included diabetes mellitus (HR 2.58, p<0.001), kidney stones (HR 2.14, p=0.01), radiographic damaged joint count (HR 1.02, p=0.02), uric acid (HR 1.21, p<0.001; 50-unit increase), daily use of non-steroidal anti-inflammatory drugs (NSAIDs) (HR 1.77, p=0.02) and methotrexate use (HR 0.51, p=0.01). Conclusion CKD is not infrequent in PsA. Its development is associated with related comorbidities, joint damage and NSAID use. Methotrexate seems to be protective.