I read with great interest in a recent issue the article by Donia et al. [1] about intravenous (i.v.) cyclophosphamide (CP) in steroid-dependent nephrotic syndrome (SDNS) patients. The results of this study are interesting, but there is a point that should be mentioned.
If we remember the short history of CP usage in SDNS, there is a significant difference in the success rate of an 8-week course of CP (2 mg/kg/day oral) between patients with frequently relapsing nephrotic syndrome and those with SDNS [2]. This led to a second study of a 2 mg/kg/day oral 12-week course of CP for SDNS, resulting in long-term remission (>2 years) in 67% of patients compared with 22% of patients with SDNS who had previously been treated for 8 weeks [3]. From this information, an essential point of CP treatment in SDNS patients is the treatment period. This means that the cumulative dosage of CP is the main factor which determines the response in SDNS. According to our recent article, in which we compared the efficiency of oral and i.v. CP, we found that annual relapse rates (0.38 for the oral group; 0.23 for the i.v. group), subsequent relapse time (19.5 months for the oral group, 31.5 months for the i.v. group) and dosage of prednisone that maintained remission after CP (3.06 mg/m2/alternate days for the oral group, 1.5 mg/m2/alternate days for the i.v. group) were significantly different. The proportion of patients in full remission for 2 years was 33.3% in the oral CP group and 50% in the i.v. CP group (P<0.05) without any significant side effects [4]. The main difference between our study and the group studied by Donia et al. [1] is the withdrawal time of the steroids. Donia et al. discontinued steroids at 2 months following the start of CP and lost more than half of the patients with relapse before CP has reached the cumulative effective dosage. Because of this, the results of this study must be unjust for reporting the efficiency of i.v. CP.
Conflict of interest statement. None declared.
Kocaeli University Hospital Pediatric Nephrology Kocaeli Turkey Email: zbircan{at}superonline.com
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