Although dialysis is typically started in an effort to prolong survival, mortality is reportedly high in the first few months. However, it remains unclear whether this is true in Japanese patients who tend to have a better prognosis than other ethnicities, and if health conditions such as functional status (FS) at initiation of dialysis influence prognosis. We investigated the epidemiology of early death and its association with FS using Japanese national registry data in 2007, which included 35,415 patients on incident dialysis and 7,664 with FS data. The main outcome was early death, defined as death within 3 months after initiation of hemodialysis (HD). The main predictor was FS at initiation of HD. Levels of functional disability were categorized as follows: severe (bedridden), moderate (overt difficulties in exerting basic activities of daily living), or mild/none (none or some functional disabilities). Early death remained relatively common, especially among elderly patients (overall: 7.1%; those aged ≥80 years: 15.8%). Severely and even only a moderately impaired FS were significantly associated with early death after starting dialysis (adjusted risk ratios: 3.93 and 2.38, respectively). The incidence of early death in those with impaired FS increased with age (36.5% in those with severely impaired FS and aged ≥80 years). Early death after starting dialysis was relatively common, especially among the elderly, even in Japanese patients. Further, early death was significantly associated with impaired FS at initiation of HD.

This review article series on water and electrolyte disorders is based on the 'Electrolyte Winter Seminar' held annually for young nephrologists in Japan. The seminar includes lively discussions based on cases, which are also partly included in this series as self-assessment questions. The first article in this series focuses on pathophysiology, symptoms, outcomes, and evaluation of hyponatremia, a common water and electrolyte disorder in clinical practice. Diagnosing the root cause(s) of hyponatremia can be challenging due to various etiologies and co-morbidities that affect water and electrolyte homeostasis, which can result in inappropriate management and worse outcomes in acute and chronic hyponatremia. This review provides an overview of pathophysiology, symptoms, outcomes, and evaluation of hyponatremia for better comprehension and improved clinical practice.

This review article series on water and electrolyte disorders is based on the ‘Electrolyte Winter Seminar’ held annually for young nephrologists in Japan. This is the third article in this series that focuses on water and electrolyte disturbances caused by novel pharmacological agents for kidney disease and cancer. The advent of novel pharmacological agents in cardiorenal medicine and oncology has introduced both therapeutic benefits and challenges in managing medication-induced water and electrolyte disturbances. These medications, including sodium–glucose cotransporter-2 (SGLT2) inhibitors, non-steroidal mineralocorticoid receptor antagonists (ns-MRAs), and immune checkpoint inhibitors (ICIs), significantly impact water and electrolyte homeostasis. SGLT2 inhibitors used widely in diabetes mellitus, heart failure, and chronic kidney disease mitigate hyperkalemia and hypomagnesemia but increase the risk of hypernatremia in patients on fluid restriction. Conversely, they are beneficial for managing hyponatremia in the syndrome of inappropriate antidiuresis (SIAD). ns-MRAs, prescribed for diabetic kidney disease, exhibit a high risk of hyperkalemia, particularly when combined with renin–angiotensin system inhibitors. ICIs, a breakthrough in oncology, frequently induce hyponatremia through immune-related adverse events, such as hypophysitis and non-immune-related adverse events like SIAD. Understanding the pathophysiology of these disturbances and implementing timely interventions, including hormone replacement and water and electrolyte management, is critical for optimizing treatment outcomes.