Interventional nephrology: current status and clinical impact in Japan

Current status and clinical significance of interventional nephrology has not been reported from Japan. Questionnaires were mailed twice to the directors of all 534 Japanese certificated nephrology training institutions in 2014. The main questions were current performance, categorized annual procedure volume and managers of peritoneal dialysis (PD) access, vascular access (VA) surgery, endovascular intervention, and kidney biopsy. Frequencies of nephrologist involvement between high volume center and low volume center and association between the level of nephrologists' involvement to each procedure and annual procedure volume were examined. 332 (62.2%) institutions answered performance of all procedures and 328 (61.4%) institutions answered all procedure volume. Kidney biopsy, VA surgery, endovascular intervention and PD access surgery were performed by any doctors in 94.2, 96.3, 88.4, and 76.2% and each involvement of nephrologist was 93.9, 54.1, 53.1 and 47.6%, respectively. Cochran-Armitage analyses demonstrated significant increases in all 4 procedure volume with greater management by nephrologists (p < 0.01). Nephrologists involvement to VA surgery associated with procedure volume increase in not only VA surgery, but also PD catheter insertion (p < 0.01) and kidney biopsy (p < 0.05). And nephrologists involvement to PD catheter insertion also associated with surgical volume increase in both VA surgery (p < 0.01) and endovascular intervention (p < 0.05). Main manager of all 4 procedures was nephrologist in Japan. Each procedure volume increased as nephrologists become more involved. Acquisition of one specific procedure by nephrologist associated with increase not only in this specific procedure volume, but also the other procedure volume.