The use of anti-adrenergic agents as a predictor of acute kidney injury and delayed recovery of kidney function: the NARA-AKI cohort study.

Association of preoperative regular use of anti-adrenergic agents with postoperative acute kidney injury (AKI) and with trajectory of kidney function after AKI is still unknown. In a retrospective cohort study, adults undergoing non-cardiac surgery under general anesthesia were included. Obstetric or urological surgery, missing data, or preoperative dialysis was excluded. The exposure of interest was preoperative regular use of anti-adrenergic agents. The outcomes were AKI within 1 week postoperatively and trajectories of kidney function within 2 weeks postoperatively among patients with AKI. Multivariable logistic regression models were used to examine the association of anti-adrenergic agents with AKI. Linear mixed-effects models were used to compare the trajectories of postoperative kidney function after AKI between patients with and without anti-adrenergic agents. Among 5168 patients, 245 had used anti-adrenergic agents. A total of 309 (6.0%) developed AKI, and the use of anti-adrenergic agents was independently associated with postoperative AKI even after adjustment for preoperative and intraoperative potential confounders [odds ratio (95% confidence interval): 1.76 (1.14-2.71)]. The association was similar across preexisting hypertension or cardiovascular disease. Analyses restricted to patients with AKI suggested that the timing and stage of AKI were similar among those with and without anti-adrenergic agents; however, the recovery of kidney function was delayed among those with anti-adrenergic agents (P for interaction = 0.004). The use of anti-adrenergic agents was associated with postoperative AKI and delayed recovery of kidney function after AKI. Temporary withdrawal of anti-adrenergic agents during perioperative periods may contribute to prevent AKI and shorten the duration of AKI.

Kidney function at 3 months after acute kidney injury is an unreliable indicator of subsequent kidney dysfunction: the NARA-AKI Cohort Study.

BACKGROUND: The relationship between kidney function at 3 months after acute kidney injury (AKI) and kidney function prognosis has not been characterized. METHODS: This retrospective cohort study included adults who underwent noncardiac surgery under general anesthesia. Exclusion criteria included obstetric or urological surgery, missing data and preoperative dialysis. Linear mixed-effects models were used to compare estimated glomerular filtration rate (eGFR) slopes in patients with and without AKI. Multivariable Cox proportional hazard models were used to examine the associations of AKI with incident chronic kidney disease (CKD) and decline in eGFR ≥30%. RESULTS: Among 5272 patients, 316 (6.0%) developed AKI. Among 1194 patients with follow-up creatinine values, eGFR was stable or increased in patients with and without AKI at 3 months postoperatively and declined thereafter. eGFR decline after 3 months postoperatively was faster among patients with AKI than among patients without AKI (P = .09). Among 938 patients without CKD-both at baseline and at 3 months postoperatively-226 and 161 developed incident CKD and a decline in eGFR ≥30%, respectively. Despite adjustment for eGFR at 3 months, AKI was associated with incident CKD {hazard ratio [HR] 1.73 [95% confidence interval (CI) 1.06-2.84]} and a decline in eGFR ≥30% [HR 2.41 (95% CI 1.51-3.84)]. CONCLUSIONS: AKI was associated with worse kidney outcomes, regardless of eGFR at 3 months after surgery. Creatinine-based eGFR values at 3 months after AKI might be affected by acute illness-induced loss of muscle mass. Kidney function might be more accurately evaluated much later after surgery or using cystatin C values.

Renal histological continuum of TAFRO syndrome: A case report and literature review.

TAFRO syndrome is a rare systemic inflammatory disorder that is characterized by thrombocytopenia, anasarca, fever, reticulin fibrosis, and organomegaly. Progressive renal involvement is frequently observed in patients with TAFRO syndrome, and the renal histological findings remain limited. A 52-year-old man with thymoma that was detected by chest computed tomography was admitted to our hospital because of dyspnea and abdominal distension. He had a rapid reappearance of pleural and abdominal effusion following repeated puncture with inflammation and kidney involvement on admission. Renal histology showed glomerular lesions denoting diffuse endocapillary proliferative glomerulonephritis, without any crescentic glomeruli, which was diagnosed as thrombotic microangiopathy (TMA)-like glomerulopathy. Together with histological findings of thymoma and progressively emergent thrombocytopenia, the patient was diagnosed with TAFRO syndrome. Corticosteroid and tocilizumab administration ameliorated the renal insufficiency and his clinical condition relevant to TAFRO syndrome, but there was a rapid concomitant appearance of massive proteinuria. A second renal biopsy revealed membranoproliferative glomerulonephritis (MPGN)-like glomerulopathy with de novo sclerosing and crescentic glomeruli development. Patients with TAFRO syndrome show glomerular lesions that are consistent with TMA- or MPGN-like lesions, but their clinical data are similar between the two glomerulopathies. It remains controversial whether the two are a histopathological continuum or distinct diseases. This case shows that glomerular lesions had TMA-like glomerulopathy in the acute stage of TAFRO syndrome, while the histopathology pattern favors MPGN in the chronic stage, as confirmed by repeated renal biopsies. TAFRO syndrome disease activity may not always correspond to that of glomerulopathy that is associated with TAFRO syndrome.

External Validation of a Prediction Model for Acute Kidney Injury Following Noncardiac Surgery.

Importance: The Simple Postoperative AKI Risk (SPARK) index is a prediction model for postoperative acute kidney injury (PO-AKI) in patients undergoing noncardiac surgery. External validation has not been performed. Objective: To externally validate the SPARK index. Design, Setting, and Participants: This single-center retrospective cohort study included adults who underwent noncardiac surgery under general anesthesia from 2007 to 2011. Those with obstetric or urological surgery, estimated glomerular filtration rate (eGFR) of less than 15 mL/min/1.73 m2, preoperative dialysis, or an expected surgical duration of less than 1 hour were excluded. The study was conducted at Nara Medical University Hospital. Data analysis was conducted from January to July 2021. Exposures: Risk factors for AKI included in SPARK index. Main Outcomes And Measures: PO-AKI, defined as an increase in serum creatinine of at least 0.3 mg/dL within 48 hours or 150% compared with preoperative baseline value or urine output of less than 0.5 mL/kg/h for at least 6 hours within 1 week after surgery, and critical AKI, defined as either AKI stage 2 or greater and/or any AKI connected to postoperative death or requiring kidney replacement therapy before discharge. The discrimination and calibration of the SPARK index were examined with area under the receiver operating characteristic curves (AUC) and calibration plots, respectively. Results: Among 5135 participants (2410 [46.9%] men), 303 (5.9%) developed PO-AKI, and 137 (2.7%) developed critical AKI. Compared with the SPARK cohort, participants in our cohort were older (median [IQR] age, 56 [44-66] years vs 63 [50-73] years), had lower baseline eGFR (median [IQR], 82.1 [71.4-95.1] mL/min/1.73 m2 vs 78.2 [65.6-92.2] mL/min/1.73 m2), and had a higher prevalence of comorbidities (eg, diabetes: 3956 of 51 041 [7.8%] vs 802 [15.6%]). The incidence of PO-AKI and critical AKI increased as the scores on the SPARK index increased. For example, 10 of 593 participants (1.7%) in SPARK class A, indicating lowest risk, experienced PO-AKI, while 53 of 332 (16.0%) in SPARK class D, indicating highest risk, experienced PO-AKI. However, AUCs for PO-AKI and critical AKI were 0.67 (95% CI, 0.63-0.70) and 0.62 (95% CI, 0.57-0.67), respectively, and the calibration was poor (PO-AKI: y = 0.24x + 3.28; R2 = 0.86; critical AKI: y = 0.20x + 2.08; R2 = 0.51). Older age, diabetes, expected surgical duration, emergency surgery, renin-angiotensin-aldosterone system blockade use, and hyponatremia were not associated with PO-AKI in our cohort, resulting in overestimation of the predicted probability of AKI in our cohort. Conclusions and Relevance: In this study, the incidence of PO-AKI increased as the scores on the SPARK index increased. However, the predicted probability might not be accurate in cohorts with older patients with more comorbidities.

Anemia following acute kidney injury after noncardiac surgery and long-term outcomes: the NARA-AKI cohort study.

Background: This study was conducted to investigate whether acute kidney injury (AKI) is an independent predictor of anemia and whether anemia following AKI is a mediator of mortality after AKI. Methods: This is a retrospective cohort study. Adults with noncardiac surgery from 2007 to 2011 were included. Obstetric or urological surgery, missing data or preoperative dialysis were excluded. Subjects were followed until the end of 2015 or lost to follow-up. Exposures of interest were postoperative AKI. Outcome variables were hematocrit values at 3, 6 and 12 months postoperatively and mortality. Associations between AKI and hematocrit or association between AKI and mortality were examined by multivariable linear regression or Cox regression, respectively. Results: Among 6692 subjects, 445 (6.6%) developed AKI. Among those with postoperative data, AKI was independently associated with lower hematocrit at 3, 6 and 12 months postoperatively, with coefficients of -0.79 [95% confidence interval (CI) -1.47 to -0.11; n = 1750], -1.35 (-2.11 to -0.60; n = 1558) and -0.91 (-1.59 to -0.22; n = 2463), respectively. Higher stages or longer duration of AKI were associated with more severe anemia. AKI was associated with higher mortality after 3 months postoperatively with a hazard ratio of 1.54 (95% CI 1.12-2.12). Further adjustment with hematocrit at 3 months attenuated the association. The mediation effect was significant (P = 0.02) by mediation analysis. Conclusions: AKI was an independent predictor of anemia following AKI. Higher mortality associated with AKI was at least partially mediated by anemia following AKI. Whether correction of anemia following AKI improves mortality requires further research.

Relationship between initial peritoneal dialysis modality and risk of peritonitis.

Peritonitis is a critical complication of peritoneal dialysis (PD). Investigators have reported the risk of peritonitis in patients on continuous ambulatory peritoneal dialysis (CAPD) versus automated peritoneal dialysis (APD), but the available evidence is predominantly based on observational studies which failed to report on the connection type. Our understanding of the relationship between peritonitis risk and PD modality thus remained insufficient. We studied 285 participants who began PD treatment between 1997 and 2014 at three hospitals in Nara Prefecture in Japan. We matched 106 APD patients with 106 CAPD patients based on their propensity scores. The primary outcome was time to first episode of peritonitis within 3 years after PD commencement. In total, PD peritonitis occurred in 64 patients during the study period. Patients initiated on APD had a lower risk of peritonitis than did those initiated on CAPD in both the unadjusted and adjusted models. The hazard ratio (HR) and 95% confidence interval (CI) for the primary endpoint were 0.30 (0.17-0.53) in the fully adjusted model including connection type. In the matched cohort, APD patients had a significantly lower risk of peritonitis than did CAPD patients (log-rank: p < 0.001, HR 0.32, 95% CI 0.16-0.59). The weighting-adjusted analysis of the inverse probability of treatment yielded a similar result (HR 0.35, 95% CI 0.18-0.67). In conclusion, patients initiated on APD at PD commencement had a reduced risk of peritonitis compared with those initiated on CAPD, suggesting APD may be preferable for prevention of peritonitis among PD patients.

Pre-operative proteinuria and post-operative acute kidney injury in noncardiac surgery: the NARA-Acute Kidney Injury cohort study.

BACKGROUND: Little is known about the association between pre-operative proteinuria and post-operative acute kidney injury (AKI) in noncardiac surgery. METHODS: This is a retrospective cohort study. Adults who underwent noncardiac surgery under general anesthesia from 2007 to 2011 at Nara Medical University Hospital were included. Those with obstetric or urological surgery, missing data for analyses or pre-operative dialysis were excluded. Exposure of interest was pre-operative proteinuria, defined as (+) or more by dipstick test. The outcome variable was post-operative AKI, defined by Kidney Disease: Improving Global Outcomes criteria, within 1 week after surgery. Multivariable logistic regression analyses were performed. RESULTS: Among 5168 subjects, 309 (6.0%) developed AKI. Pre-operative proteinuria was independently associated with post-operative AKI, with an odds ratio (OR) [95% confidence interval (CI)] of 1.80 (1.30-2.51). A sensitivity analysis restricted to elective surgery yielded a similar result. As proteinuria increased, the association with AKI became stronger [OR (95% CI) 1.14 (0.75-1.73), 1.24 (0.79-1.95), 2.75 (1.74-4.35) and 3.95 (1.62-9.62) for urinary protein (+/-), (+), (2+) and (3+), respectively]. Subgroup analyses showed proteinuria was especially associated with post-operative AKI among subjects with renin-angiotensin system inhibitors, other anti-hypertensives, hypoalbuminemia or impaired renal function (P for interaction = 0.05, 0.003, 0.09 or 0.02, respectively). CONCLUSIONS: In noncardiac surgery, pre-operative proteinuria was independently associated with post-operative AKI. Subjects with proteinuria should be managed with caution to avoid AKI peri-operatively.

Positive association between intra-operative fluid balance and post-operative acute kidney injury in non-cardiac surgery: the NARA-AKI cohort study.

BACKGROUND: Little is known about the association between intra-operative fluid balance (IFB) and post-operative acute kidney injury (AKI) in non-cardiac surgery. METHODS: This is a retrospective cohort study. Adults who underwent non-cardiac surgery under general anesthesia from 2007 to 2011 at Nara Medical University Hospital were included. Those with obstetric or urological surgery, missing data, or pre-operative dialysis were excluded. Exposure of interest was IFB, defined as (amount of fluid administration - urine output - amount of bleeding)/body weight. Outcome variable was post-operative AKI within 1 week after surgery. Data were analyzed using logistic regression models and restricted cubic spline (RCS) analysis. RESULTS: Among 5168 subjects, AKI was observed in 309 (6.0%). Higher IFB (per 1 standard deviation) was independently associated with post-operative AKI after adjustment for potential confounders (odds ratio [95% confidence interval] of 1.18 [1.06-1.31]). The RCS curve showed an increase in expected probability of AKI associated with increase in IFB above 40 mL/kg. Subgroup analyses indicated higher IFB was especially associated with AKI among those with lower serum albumin, higher C-reactive protein, or positive proteinuria. The association was similar across intra-operative urine output or amount of bleeding (p for interaction 0.34 and 0.47, respectively), suggesting the association was not due to intra-operative oliguria or large amount of bleeding necessitating volume resuscitation. CONCLUSIONS: Higher IFB was independently associated with increase in post-operative AKI. Excessive fluid administration might have caused renal congestion and subsequent AKI. Avoiding fluid overload might be important in prevention of AKI.

Acute kidney injury as an independent predictor of infection and malignancy: the NARA-AKI cohort study.

BACKGROUND: Acute kidney injury (AKI) is associated with higher mortality and cardiovascular events. However, association between AKI and non-cardiac events such as infection or malignancy is largely unknown. METHODS: This is a retrospective cohort study. Inclusion criteria were adults who underwent non-cardiac surgery from 2007 to 2011 at Nara Medical University Hospital. Exclusion criteria were urological surgery, obstetric surgery, missing creatinine values peri-operatively, and pre-operative dialysis. The end of observation period was at the end of 2015 or loss to follow-up. A predictor was AKI defined by KDIGO criteria within 1-week post-operatively. Outcomes were hospitalization for infection or diagnoses of malignancy. Associations between AKI and outcomes were examined by Cox regression models. RESULTS: Among 6692 subjects, 445 (6.6%) developed AKI. During median follow-up of 4.0 years, there were 485 hospitalizations for infection and 1138 diagnoses of malignancy (2.0 and 5.1 events/100 patient-years, respectively). After adjustment for potential confounders, AKI was independently associated with hospitalization for infection and diagnoses of malignancy (Hazard ratio [95% confidence interval]: 1.64 [1.23-2.20] and 1.31 [1.06-1.61], respectively). Excluding recurrence of malignancy from outcomes and analyses limited to those who recover renal function by the time of discharge yielded similar results. Absolute lymphocyte counts were significantly lower and neutrophil-to-lymphocyte ratios were significantly higher among those with AKI. CONCLUSIONS: AKI was significantly associated with hospitalization for infection and development of malignancy during long-term follow-up. Those with AKI might be in persistent immunosuppressed state.

Inflammation as a predictor of acute kidney injury and mediator of higher mortality after acute kidney injury in non-cardiac surgery.

This retrospective cohort study examined the roles of inflammation in acute kidney injury (AKI). Serum albumin and C-reactive protein (CRP) were used as markers of inflammation. Adults who underwent non-cardiac surgery from 2007 to 2011 were included. Exclusion criteria were urological surgery, obstetric surgery, missing data, and pre-operative dialysis. Subjects were followed until the end of 2015 or loss to follow-up. Associations between pre-operative albumin or CRP and post-operative AKI or association between AKI and mortality were examined by logistic or Cox regression, respectively. Mediation analyses were performed using albumin and CRP as mediators. Among 4,538 subjects, 272 developed AKI. Pre-operative albumin was independently associated with AKI (odds ratio [95% confidence interval (CI)]: 0.63 [0.48-0.83]). During a median follow-up of 4.5 years, 649 died. AKI was significantly associated with mortality (hazard ratio [HR] [95% CI]: 1.58 [1.22-2.04]). Further adjustment for pre-operative albumin and CRP attenuated the association (HR [95% CI]: 1.28 [0.99-1.67]). The proportions explained by mediating effects of lnCRP and albumin were 29.3% and 39.2% and mediation effects were statistically significant. In conclusion, inflammation is a predictor of AKI and a mediator of mortality after AKI. Interventions targeting inflammation might improve outcomes of AKI.