Prevalence of and factors associated to chronic kidney disease and hypertension in a cohort of children with juvenile idiopathic arthritis.

We evaluated chronic kidney disease (CKD) (proteinuria or estimated glomerular filtration rate < 60 mL/min/1.73 m) or hypertension prevalence in 110 children with juvenile idiopathic arthritis (JIA). CKD and hypertension were clustered under the umbrella term of "renal injury". Median age at the last visit was 14 years. Nine out of 110 (8.1%) patients showed renal injury (8 hypertension, 1 proteinuria). Patients with renal injury presented higher age at last visit, longer duration of active JIA, shorter intervals free from JIA relapses, longer duration of non-steroidal anti-inflammatory drugs (NSAIDs) treatment but with similar cumulative NSAIDs dose and higher rate of methotrexate (MTX) prescription, longer time of MTX administration, and higher cumulative MTX dose compared to patients without renal injury. At the last visit, patients with and without renal injury presented similar prevalence of active disease. The cumulative proportion of patients free from renal injury at 240 months since JIA onset was 40.72% for all population; while the cumulative proportion was 23.7% for patients undergoing NSAIDs+MTX treatment and 100% for those undergoing NSAIDs (p = 0.039) treatment.Conclusion:About 8% of the children with JIA develop hypertension or CKD. The main risk factor was longer exposure to both NSAIDs and MTX due to a more severe form of the disease. What is Known •Anecdotal reports showed that rarely juvenile idiopathic arthritis (JIA) could present renal involvement due to prolonged and uncontrolled inflammation (renal amyloidosis) or to long exposure to anti-rheumatic drugs. •No cohort studies investigated renal health in children with JIA. What is new •About 8% of the children with JIA developed hypertension or chronic kidney disease. •The main risk factor was long exposure to non-steroidal anti-inflammatory drugs and methotrexate for patients suffering from a more severe form of the disease. •In JIA patients, periodic evaluation of renal function, blood pressure and proteinuria should be warranted.