Urinalysis monitoring in children with Henoch-Schönlein purpura: Is it time to revise?

Abstract

Objectives: To describe the natural history and risk factors of renal involvement in our Henoch-Schönlein purpura (HSP) inception cohort.

Methods: HSP patients followed at our center for at least 6 months between 1/2009-4/2017 were included. A 2-year urinalysis (UA) monitoring protocol was adopted (6 monthly and another 6 of 3 monthly UA). Renal involvement included minimal renal involvement defined as isolated hematuria (urine red blood cells >5/high-power field or 10/µL) and/or proteinuria (urine protein >1+), and renal impairment defined as nephritic, nephrotic symptoms, or renal insufficiency. Recurrent HSP were excluded. Kaplan-Meier estimates and log-rank test were used to analyze the duration to onset and resolution of abnormal UA. Relationships between demographic and clinical features and renal involvement were studied using logistic regression analyses.

Results: Two hundred and thirty-eight patients (52.9% male) were analyzed. Median duration of follow up was 20.6 (interquartile range 11.3-24.4) months. Eighty-nine children (37.4%) developed abnormal UA either at diagnosis (n = 43), or during follow up (n = 46), mostly (91.0%) within 6 months. Seventeen patients (7.1%) developed renal impairment. Among patients without renal impairment, an earlier subsidence (P = 0.008) was noted in those with normal UA at diagnosis and most abnormal UA resolved by 18 months in this subgroup. Older age at diagnosis was a risk factor of renal involvement (P < 0.001). Prednisolone therapy for non-renal indications did not affect the onset or duration of renal involvement.

Conclusions: Normal UA at diagnosis indicated a shorter duration of renal involvement. We propose a curtailed duration of follow up for those with normal and abnormal UA at diagnosis.

Keywords: HSP; Henoch-Schönlein purpura; pediatric rheumatology; systemic vasculitis; urinalysis.