Dyschloremia is associated with failure to restore renal function in survivors with acute kidney injury: an observation retrospective study

www.nature.com/scientificreports OPEN Dyschloremia is associated with failure to restore renal function in survivors with acute kidney injury: an observation retrospective study Youn Kyung Kee, Hee Jung Jeon, Jieun Oh & Dong Ho Shin* Dyschloremia is common in critically ill patients. However, little is known about the effects of dyschloremia on renal function in patients with acute kidney injury (AKI) requiring continuous renal replacement therapy (CRRT). A total of 483 patients who received CRRT for AKI were selected and divided into three groups according to their serum chloride concentrations at the time of CRRT initiation. At 90 days after initiating CRRT, renal outcome, i.e., non-complete renal recovery, or renal failure, was assessed in the three groups. The hypochloremia group (serum chloride concentrations < 96 mEq/L, n = 60), the normochloremia group (serum chloride concentrations, 96–111 mEq/L, n = 345), and the hyperchloremia group (serum chloride concentrations > 111 mEq/L, n = 78) were classified. The simplified acute physiology score III was higher in the hyperchloremia and hypochloremia groups than in the normochloremia group. Multivariate logistic regression analyses showed that hypochloremia (odds ratio, 5.12; 95% confidence interval [CI], 2.56–10.23; P < 0.001) and hyperchloremia (odds ratio, 2.53; 95% CI, 1.25–5.13; P = 0.01) were significantly associated with non-complete renal recovery. Similar trends were observed for renal failure. This study showed that dyschloremia was independently associated with failure in restoring renal function following AKI. Severe acute kidney injury (AKI) requiring renal replacement therapy (RRT) is a common serious complication in critically ill patients and is associated with high mortality and morbidity1–4. Although critical care and dialysis technology have improved significantly, the mortality in patients with severe AKI requiring RRT is higher than in those with other serious diseases, such as acute respiratory distress syndrome or myocardial infarction5,6. In addition, survivors with severe AKI requiring RRT are known to have a high risk of developing long-term complications, such as chronic kidney disease (CKD) or renal f ailure4. Chloride is a major extracellular anion in the blood which constitutes approximately one-third of extracellular fluid tonicity7,8. In addition, it plays several important roles in the body, such as maintaining electrical activity, acid–base balance, fluid and gastrointestinal homeostasis, and renal f unction7,9–11. Despite its physiological and clinical importance, less attention has been paid to chloride than other routinely measured electrolytes in critically ill patients8. Dyschloremia commonly observed in critically ill patients can occur because of various etiologic factors associated with the illness or t reatment7,12,13. Although there have been few outcome-related studies on dyschloremia, several studies showed that dyschloremia is associated with significantly increased mortality and m orbidity11,14–16. Some studies have shown that hyperchloremia could reduce renal blood flow and glomerular filtration rate (GFR) and consequently, cause salt and water retention to occur17,18. These findings suggest that hyperchloremia is associated with AKI based on clear biological plausibility. In fact, accumulation of clinical evidence also suggests that hyperchloremia is associated with AKI in critically ill p atients19,20. Although there is no clear experimental evidence for hypochloremia-associated AKI, some observational clinical studies have shown that hypochloremia is associated with A KI21,22. Moreover, renal recovery following AKI is clinically important because AKI had been found to be an independent risk factor for the development of CKD or the progression from CKD to renal failure23. However, there is limited knowledge regarding the association between serum chloride concentrations and renal recovery in patients with AKI. Thus, this study aimed to determine Department of Internal Medicine, College of Medicine, Kangdong Sacred Heart Hospital, Hallym University, 150, Seongan‑ro, Gangdong‑gu, Seoul 05355, Korea. *email: Scientific Reports | (2020) 10:19623 | https://doi.org/10.1038/s41598-020-76798-5 1 Vol.:(0123456789) www.nature.com/scientificreports/ Figure 1.  Patient inclusions and subgroupings. whether dyschloremia was associated with failure to restore renal function in survivors having severe AKI and requiring RRT. Results Study population. During the 10-year study period, 1276 patients were included. Of 1276 patients, 834 patients survived at 90 days after initiating continuous renal replacement therapy (CRRT). Of 834 survivors, 351 were excluded: 176 patients with severe CKD, 34 patients whose cause of AKI was urinary tract obstruction, tumor lysis syndrome, thrombotic microangiopathy or acute glomerulopathy, 15 patients who received CRRT after kidney transplantation, 13 patients who were referred to other clinics within 90 days, and 113 patients without records in the laboratory database within 12 months before hospital admission (Fig. 1). Characteristics at the time of CRRT. Overall, 483 patients with AKI requiring CRRT were included in this study, of whom 293 were men. The mean age of the patients was 65.6 years, and sepsis in 154 patients (31.9%) was the most common cause of AKI at the time of CRRT initiation. The median Charlson Comorbidity Index (CCI), Sequential Organ Failure Assessment (SOFA) score, and mean simplified acute physiology score III (SAPS III) were 2.0 (0.0–3.0), 9 (8.0–11.0), and 43.9 ± 8.5, respectively. The patients were divided into three groups according to the degree of dyschloremia (hypochloremia, normochloremia, and hyperchloremia); 60 (12.4%) were in the hypochloremia group, 345 (71.4%) were in the normochloremia group, and 78 (16.1%) were in the hyperchloremia group. Although patients with hypochloremia had comparable CCIs to patients with normochloremia, those with hypochloremia had a higher prevalence of congestive heart failure than those with normochloremia. Meanwhile, patients with hypochloremia and hyperchloremia had higher SAPS III than patients with normochloremia (Table 1). Of note, all patients had blood sampling at 90 days after CRRT initiation. Kidney outcome according to chloride category. Of 483 patients, 111 (23%) had non-complete renal recovery and 69 (14.3%) had renal failure at 90 days after initiating CRRT. The incidence of non-complete renal recovery was significantly lower in the normochloremia group than in the other groups (P < 0.001). Although there was no significant difference in the incidence of renal failure among three groups, a similar pattern was observed in the development of renal failure (Fig. 2). Factors associated with renal outcome. In logistic regression analysis, CKD, CHF, high CCIs, high creatinine concentrations, and dyschloremia were independently associated with non-complete re (...truncated)