To clarify the epidemiology of DKI in Japan, we reviewed the reports of DKI for elderly persons from the study of a Health and Labour Science Research Grant from the Ministry of Health, Labour, and Welfare (2007–2009) and analyzed the data of the Japan-Kidney Disease Registry (J-KDR) from 2007 to 2012.
In the reports of DKI for elderly persons (2007–2009), DKI accounted for approximately 1 % of all admitted patients in the hospitals of 47 representative nephrologists. The major drugs inducing renal injury were non-steroidal anti-inflammatory drugs (NSAIDs) in 25.1 % of cases, anti-cancerous drugs in 18.0 %,antibiotic agents in 17.5 %, and radio-contrast agents in 5.7 %. Of these cases, 54.6 % were of the direct renal injury type. Moreover, the kidney function of 36.5 % of these patients did not recover.
A total of 231 cases of DKI, including 224 renal-biopsy-proven cases, had been registered on J-KDR in 2007–2012 (1.42 % of 15,821 cases). The frequency of DKI increased with aging. Elderly patients in their 70s showed a three times higher frequency of DKI as compared to less than 10 year (1.83 vs. 0.65 %). The major clinical diagnoses of these cases were DKI in 118 cases (51.1 %), nephrotic syndrome in 42 cases (18.2 %), chronic nephritic syndrome in 42 cases (17.7 %), and rapidly progressive nephritic syndrome in 19 cases (8.2 %). The pathological findings of these cases were glomerular injuries in 67 cases (29.0 %), acute tubule-interstitial injuries in 60 cases (26.0 %), chronic tubule-interstitial injuries in 55 cases (23.8 %), and sclerotic glomerular lesion and/or nephrosclerosis in 18 cases (7.8 %). Both acute and chronic tubulo-interstitial injuries were mainly related to the clinical diagnosis of DKI. On the other hand, nephrotic syndrome mainly due to membranous nephropathy was the major cause of glomerular injuries in 44.4 %. The prevalence of these diagnosis was peaked in the 60s and 70s in all categories, excepting for chronic tubulo-interstitial injuries, which peaked in their 30s and 40s. According to the risk category of CKD (heat map), 80.6, 75.9, and 40.9 % of acute and chronic tubulo-interstitial injuries and glomerular injury were categorized as high-risk (red zone) cases, respectively.
The causative drugs identified in 71 cases, which included bucillamine in 26 cases with membranous nephropathy, gemucitabine in 3 cases with thrombotic microangiopathy, and propyl thiouracil in 3 cases with ANCA-related nephritis.