Relapsing childhood steroid sensitive nephrotic syndrome: what determines eventual remission?

Childhood idiopathic nephrotic syndrome (INS) responds to corticosteroids (CS), but tends to relapse, often requiring steroid sparing agents (SSA). Long standing treatment free remission (LTFR) evolves in most cases, but whether this is related to puberty or disease length is unknown.

We retrospectively analyzed the computerized database of Israel's largest health maintenance organization. Children with a new INS diagnosis between 2000-2010 were divided into 2 groups according to INS presentation age. Disease length was determined based on CS or SSA use. Children with disease shorter than 1 year or those not reaching LTFR, defined as more than 3 years from last purchase, were excluded.

Out of 1,669,977 eligible children, 608 were diagnosed with INS, 524 relapsed, 174 were excluded, leaving 350 for analysis: 272 (77.7%) and 78 (22.2%) presented between 2-6.9 and 7-9.9 years, respectively. There was no difference in the need for SSA, time to SSA initiation and drug purchase count between the groups. After 15.5 ± 5.1 years of follow up, time until LTFR was longer in the older group (5.4 ± 4 vs. 7.1 ± 5.1 years, p = 0.002), without correlation between INS onset age and disease length. Many patients, especially in the older group, still relapsed beyond Tanner stage 3's 97th percentile age (age 14 years) (14.7% vs. 51.3%, p < 0.001), irrelevant of sex.

In this population-based study LTFR occurred in many cases well beyond puberty, in both groups, favoring the role for disease length on LTFR, probably due to maturational immune system changes.