Risk of long term renal impairment and duration of follow up recommended for Henoch-Schonlein purpura with normal or minimal urinary findings: a systematic review

Background: The duration of follow up to assess the risk of long term renal impairment in Henoch-Schonlein purpura (HSP) without nephritic or nephrotic syndrome or renal failure on diagnosis remains undetermined. Aims: To undertake a systematic review of the literature to assess whether the risk of long term renal impairment without renal involvement on diagnosis could be estimated and to determine the time period when renal involvement is very unlikely after the diagnosis of HSP. Methods: Search of studies of unselected children with HSP, and available information on urinary findings, renal involvement, and long term renal function follow up. Studies of selected children with HSP nephropathy at diagnosis were excluded. Results: Twelve studies of 1133 children were reviewed. The follow up period ranged from 6 weeks to 36 years. Proteinuria and/or haematuria, which occurred in 34.2%, of which only one fifth were in association with nephritic or nephrotic syndrome, developed in 85% of cases within 4 weeks of the diagnosis of HSP, in 91% within 6 weeks, and in 97% within 6 months. Permanent renal impairment never developed after normal urinalysis; it occurred in 1.6% of those with isolated urinary abnormalities, and in 19.5% of those who developed nephritic or nephrotic syndrome. Conclusion: No long term renal impairment occurred after normal urinalysis. Even if urinalysis is normal at presentation, the testing should be continued for six months. There is no need to follow up after the first six months those whose urinalysis remains normal.