[Purpose] We sought to clarify the reasons for the decrease in the total number of dialysis patients in Japan in 2022. [Subject] Survey values for each year were obtained using the Web-based Analysis of Dialysis Data Archives (WADDA) system. These values were then adjusted for response rates based on the number of facilities. General population statistics for Japan were obtained from e-Stat of the Statistics Bureau, Ministry of Internal Affairs and Communications. [Methods] We compared the prevalence, morbidity, and mortality rates of dialysis patients according to sex and age. We also examined trends in the number of deaths by major causes of death. [Results] The prevalence rates of dialysis among people aged≥65 years, which had been on the rise before 2020, have been decreasing since 2020. Morbidity rates have consistently decreased. Mortality rates, which had been decreasing before 2020, increased for all ages after 2020. Since 2020, the number of deaths due to infectious diseases and the number of deaths due to coronavirus disease 2019 (COVID-19) pneumonia have rapidly increased. [Conclusion] The decrease in the number of dialysis patients in Japan in 2022 could be attributed to an increase in the number of deaths due to COVID-19 pneumonia after 2020.

IgG4-related disease (IgG4-RD) is a systemic condition characterized by elevated serum IgG4 levels and, histopathologically, massive infiltration of IgG4-positive lymphocytes and plasma cells, along with storiform fibrosis, leading to enlargement, nodules, or thickening. This study aimed to investigate the frequency of serum IgG4 elevation and latent IgG4-RD in patients undergoing hemodialysis. Measurement of serum IgG4 levels in 227 patients undergoing hemodialysis from four institutions showed that the mean serum IgG4 level was 34 mg/dL, and serum IgG4 elevation was observed in 12 patients (5.3％). Univariate linear regression analyses indicated that male sex, lower serum CH50 and total cholesterol levels, anti-nuclear antibody positivity, absence of hypertension, and smoking history were associated with serum IgG4 elevation. Age- and sex-adjusted analyses extracted the same factors, except for smoking history, as significant. Secondary evaluations for patients with IgG4 elevation revealed that one of the 12 patients was diagnosed with IgG4-related retroperitoneal fibrosis, which was a cause of renal failure. In patients undergoing hemodialysis, serum IgG4 elevation is more common in males, those with smoking history, or immunological abnormalities. A small proportion of patients with serum IgG4 elevation have latent IgG4-RD；thus, it is important to recognize IgG4-RD as a cause of renal failure.

We introduced a new index, termed the ʼlower limb CT calcification score,ʼ for patients undergoing hemodialysis. This score was calculated by measuring the sum (L) of the total lengths of the common iliac arteries, external iliac arteries, superficial femoral arteries, popliteal arteries, and posterior tibial arteries on plain CT. Additionally, we determined the sum (C) of calcification areas in both lower limbs from the same scans. The lower limb CT calcification score was defined as C÷L×100％. In the group of patients with peripheral artery disease (PAD), HDL cholesterol levels were low；blood glucose levels were high；ABI, SPP (plantar), PVR (ankle), and PVR (plantar) were low；and the lower limb CT calcification score was high. Lower limb CT calcification score showed a positive correlation with age, duration of dialysis, pulse pressure, coronary artery calcium score, carotid artery plaque score, and baPWV. On the other hand, it exhibited a negative correlation with HDL cholesterol levels, ABI, and PVR. In multiple regression analysis, significant independent variables for the lower limb CT calcification score were coronary artery calcium score, carotid artery plaque score, and ABI. Patients with a lower limb CT calcification score of 60％ or higher had lower survival rates compared to those with a score below 60％. Lower limb CT calcification score was identified as a significant variable in overall mortality using Cox proportional hazard analysis. Lower limb CT calcification score may be a useful indicator for predicting the progression of lower limb arterial calcification and prognosis in hemodialysis patients.

An 88-year-old woman was admitted to our hospital with a diagnosis of acute kidney injury (AKI, stage 3) in May 20XX, attributed to rapidly progressive glomerulonephritis caused by anti-glomerular basement membrane disease. Emergent hemodialysis (HD) was performed for the rapidly progressing AKI, and she was also treated with PSL combined with plasma exchange (PE). On the fifth day of hospitalization, she showed a decreased level of consciousness. We suspected antibiotic-associated encephalopathy (AAE) due to ceftriaxone (CTRX), which had been administered since admission. The next day, plasma CTRX concentration was high (198.7 μg/mL). We discontinued CTRX. We predicted that PE would promote the removal of CTRX due to its low distribution volume and high protein-binding affinity rate；however, plasma CTRX concentration did not decrease after PE. Although a temporary decrease in plasma CTRX concentration was observed after HD, effective drug elimination was not achieved the next day due to redistribution of the drug from the tissue to the blood (rebound phenomenon). After discontinuation of CTRX, the patientʼs level of consciousness improved to the same level as on admission on the 13th day. Hypoalbuminemia and the presence of the rapidly progressing AKI in the present patient may have led to a decrease in the protein-binding affinity rate of CTRX, resulting in the plasma CTRX concentration being unchanged after HD and PE. As elderly AKI patients have multiple risks for AAE, we need to take this background into account.