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Re: Follow-up of childhood Henoch-Schonlein purpura

Dear Editor,

We read with interest an article on 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. by Narchi et al.[1].

They found that the risk of long term renal impairment was only 1.6% in Henoch-Schonlein purpura (HSP) children with only isolated proteinuria or haematuria, but was much higher (19.5%) if the initial presentation was complicated by nephritic or nephrotic syndrome. Therefore, the renal biopsy in patients with HSP nephritis is indicated only in cases of nephrotic-range proteinuria, nephrotic or nephritic syndrome. Recently, however, Halling et al.[2] reported that 9 of the 13 HSP patients with only mild or moderate proteinuria had severe histological findings on renal biopsy and recommended the necessity of early renal biopsy in this group. Although rare, it may be important to identify this clinical entity, because Ronkainen et al.[3] reported that even patients with mild renal symptoms at the onset of HSP do carry a risk for severe long-term complications on the follow up of 24 years. However, it would not be rational costeffectively to perform a renal biopsy in all patients with mild or moderate renal symptoms considering the favourable outcome in HSP patients without severe symptoms.

Also, the exact meaning of long term is lacking in this report. Even though some patients were followed up over 10 years in each study, the duration of follow up was relatively short in most of patients in these papers. Although the prognosis for unselected children with HSP is relatively good, long term studies assessing the prognosis of HSN have shown that clinical recovery does not always mean favourable long-term outcome [3,4]. Goldstein et al.[4] studied former HSP patients 23.4 years later and reported highly unpredictable outcomes, in that several patients with mild initial disease and apparent complete recovery showed chronic renal insufficiency after 2 decades.

Relapsing course and the development of hypertension without any urinary abnormalities as a late sequela of HSP[5] were not considered in most of papers quoted in this article. The incidence of relapsing disease has been reported to be about 30%[6] and our previous report also demonstrated that HSP patients with relapse had higher trend to develop nephritis.[7]

Therefore, the possibility of relapse or unexpected deterioration should be explained to the parents of children with HSP as well as a favourable nature of this disease and further studies in a large cohort are necessary to elucidate the natural course and long term outcome of HSP.

References

1. Narchi H. 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. Arch Dis Child 2005;90(9):916-920.

2. Halling SF, Soderberg MP, Berg UB. Henoch-Schonlein nephritis: clinical findings related to renal function and morphology. Pediatr Nephrol 2005;20(1):46-51.

3. Ronkainen J, Nuutinen M, Koskimies O. The adult kidney 24 years after childhood Henoch-Schonlein purpura: a retrospective cohort study. Lancet 2002;360(9334):666-670.

4. Goldstein AR, White RH, Akuse R, Chantler C. Long-term follow-up of childhood Henoch-Schonlein nephritis. Lancet 1992;339(8788):280-282.

5. Nussinovitch N, Elishkevitz K, Volovitz B, Nussinovitch M. Hypertension as a late sequela of Henoch-Schonlein purpura. Clin Pediatr 2005;44(6):543 -547.

6. Sonmez F, Mir S, Cura A, Cakir D, Basdemir G. Clinicopathologic correlations of Henoch-Schonlein nephritis in Turkish children. Pediatr Int 1999;41(4):353-356.

Send letter to journal:
Re: Author's reply to Lee et al: Follow-up of childhood Henoch-Schonlein purpura

Dear Editor,

Lee et al. correctly mention that some children with Henoch-Schonlein purpura and only mild or moderate proteinuria may develop severe histological findings on renal biopsy[1] as well as severe long-term renal complications.[2] However, this statement adds nothing to the debate we wished to stimulate as we have never disputed this well established fact, but instead focused our review exclusively on children with normal or minimal urinary abnormalities. We therefore intentionally excluded the studies mentioned by Lee et al. as they referred to children with established nephritis on diagnosis of HSP.[1][3][4] As the risk of long-term renal damage in some children with minimal urinary findings[2] was already included in the risk we calculated in our review, Lee’s reference to that article adds therefore nothing new.

We fully agree that the duration of follow up was very variable amongst the reviewed reports and this was thoroughly debated in our discussion. However, we would like to point out again that the study mentioned by Lee and which included a follow up of up to 23.4 years[2] was already included in our review and was fully taken into consideration when calculating the risk we reported. I fail therefore to see the point that Lee et al. are trying to make here.

We had already thoroughly debated in our discussion that HSP relapses were not well defined in some of the studies we had reviewed. Furthermore, we had already made the specific point in our discussion, that the suggested follow up plan we made should be applicable not only after the diagnosis of HSP, but in addition after each recurrence of vasculitis. We made that recommendation without the benefit of the references mentioned by Lee et al, as the first[4] dealt again with children having established nephritis, therefore purposefully excluded in our review, while the other article[5] could not be retrieved in the literature search we described as it was not indexed in either Medline, or Embase or the Cochrane databases.

Finally, I am grateful to Lee et al for endorsing our recommendations for developing much larger prospective cohort studies to provide more precise estimates for the risk of long-term renal impairment in HSP with normal or minimal urinary abnormalities during the course of HSP.

Hassib Narchi

References

1. Halling SF, Soderberg MP, Berg UB. Henoch-Schonlein nephritis: clinical findings related to renal function and morphology. Pediatr Nephrol 2005;20(1):46-51.

2. Ronkainen J, Nuutinen M, Koskimies O. The adult kidney 24 years after childhood Henoch-Schonlein purpura: a retrospective cohort study. Lancet 2002;360(9334):666-670.

3. Goldstein AR, White RH, Akuse R, Chantler C. Long-term follow-up of childhood Henoch-Schonlein nephritis. Lancet 1992;339(8788):280-282.

4. Sonmez F, Mir S, Cura A, Cakir D, Basdemir G. Clinicopathologic correlations of Henoch-Schonlein nephritis in Turkish children. Pediatr Int 1999;41(4):353-356.