, Volume 9, Issue 3, pp 219-227

Study design and methods for a clinical trial of an oral carbonaceous adsorbent used to prevent the progression of chronic kidney disease (CAP-KD)

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The number of patients with chronic kidney disease (CKD) in Japan is currently rising. Therefore, measures to control the progression of CKD from a predialysis condition to endstage renal failure are urgently required. We are conducting a clinical trial to investigate the efficacy of an oral carbonaceous adsorbent (Kremezin) in patients at the predialysis stage of progressive chronic kidney disease (the Carbonaceous oral Adsorbent's effectiveness on Progression of chronic Kidney Disease [CAP-KD] trial).


A multidisciplinary treatment regimen, consisting of antihypertensive therapy (using an angiotensin-converting-enzyme inhibitor and/or an angiotensin II receptor blocker) and a low-protein diet is conventionally used to treat patients with kidney disease. To assess the efficacy of Kremezin in preventing the progression of CKD, we compare two groups of patients, receiving either conventional treatment alone or such treatment paired with Kremezin. The CAP-KD trial is a prospective, multicenter, randomized, open-label, two-arm, parallel-group comparison clinical trial and will be conducted as a researcher-directed study. The primary endpoint of this study is the time to the first event of a composite endpoint, comprising the following: (1) a doubling of serum creatinine (sCr); (2) an increase in sCr level to 6.0 mg/dl or more; (3) endstage renal disease (defined as that requiring dialysis or renal transplantation); and (4) death. Secondary endpoints are as follows: (1) variation in urinary protein; (2) changes in creatinine clearance rate; (3) changes in health-related quality of life; and (4) adverse events. The total number of patients (putative) in this trial will be 450, with 225 patients in each group. Enrollment will take place over 2 years, with a 1-year follow-up period.


As this is an ongoing trial, results are not yet available.


We believe that the CAP-KD trial is a well-designed study that will provide internationally relevant evidence concerning the outcomes of treatment in Japanese patients with CKD.