Rationale

There is a paucity of large cohort studies examining the association of obstructive sleep apnoea (OSA) with clinical outcomes including all-cause mortality, coronary heart disease (CHD), strokes and chronic kidney disease (CKD).

Objectives

We hypothesised that a diagnosis of incident OSA is associated with higher risks of these adverse clinical outcomes.

Methods, measurements

In a nationally representative cohort of over 3 million (n=3 079 514) US veterans (93% male) with baseline estimated glomerular filtration rate (eGFR)≥60 mL/min/1.73 m(2), we examined the association between the diagnosis of incident OSA, treated and untreated with CPAP, and: (1) all-cause mortality, (2) incident CHD, (3) incident strokes, (4)incident CKD defined as eGFR<60 mL/min/1.73 m(2), and (5) slopes of eGFR.

Main results

Compared with OSA-negative patients, untreated and treated OSA was associated with 86% higher mortality risk, (adjusted HR and 95% CI 1.86 (1.81 to 1.91) and 35% (1.35 (1.21 to 1.51)), respectively. Similarly, untreated and treated OSA was associated with 3.5 times (3.54 (3.40 to 3.69)) and 3 times (3.06 (2.62 to 3.56)) higher risk of incident CHD; 3.5 times higher risk of incident strokes (3.48 (3.28 to 3.64) and 3.50 (2.92 to 4.19)) for untreated and treated OSA, respectively. The risk of incident CKD was also significantly higher in untreated (2.27 (2.19 to 2.36)) and treated (2.79 (2.48 to 3.13)) patients with OSA. The median (IQR) of the eGFR slope was -0.41 (-2.01 to 0.99), -0.61 (-2.69 to 0.93) and -0.87 (-3.00 to 0.70) mL/min/1.73 m(2) in OSA-negative patients, untreated OSA-positive patients and treated OSA-positive patients, respectively.

Conclusions

In this large and contemporary cohort of more than 3 million US veterans, a diagnosis of incident OSA was associated with higher mortality, incident CHD, stroke and CKD and with faster kidney function decline.

Background

Few trials of acute kidney injury (AKI) prevention after surgery have been conducted, and most observational studies focus on AKI following cardiac surgery. The frequency of, risk factors for, and outcomes after AKI following other types of major surgery have not been well characterized and may present additional opportunities for trials in AKI.

Study design

Observational cohort study.

Setting & participants

3.6 million US veterans followed up from 2004 to 2011 for the receipt of major surgery (cardiac; general; ear, nose, and throat; thoracic; vascular; urologic; and orthopedic) and postoperative outcomes.

Factors

Demographics, health characteristics, and type of surgery.

Outcomes

Postoperative AKI defined by the KDIGO creatinine criteria, postoperative length of stay, end-stage renal disease, and mortality.

Results

Postoperative AKI occurred in 11.8% of the 161,185 major surgery hospitalizations (stage 1, 76%; stage 2, 15%, stage 3 [without dialysis], 7%; and AKI requiring dialysis, 2%). Cardiac surgery had the highest postoperative AKI risk (relative risk [RR], 1.22; 95% CI, 1.17-1.27), followed by general (reference), thoracic (RR, 0.92; 95% CI, 0.87-0.98), orthopedic (RR, 0.70; 95% CI, 0.67-0.73), vascular (RR, 0.68; 95% CI, 0.64-0.71), urologic (RR, 0.65; 95% CI, 0.61-0.69), and ear, nose, and throat (RR, 0.32; 95% CI, 0.28-0.37) surgery. Risk factors for postoperative AKI included older age, African American race, hypertension, diabetes mellitus, and, for estimated glomerular filtration rate < 90mL/min/1.73m(2), lower estimated glomerular filtration rate. Participants with postoperative AKI had longer lengths of stay (15.8 vs 8.6 days) and higher rates of 30-day hospital readmission (21% vs 13%), 1-year end-stage renal disease (0.94% vs 0.05%), and mortality (19% vs 8%), with similar associations by type of surgery and more severe stage of AKI relating to poorer outcomes.

Limitations

Urine output was not available to classify AKI; cohort included mostly men.

Conclusions

AKI was common after major surgery, with similar risk factor and outcome associations across surgery type. These results can inform the design of clinical trials in postoperative AKI to the noncardiac surgery setting.

Objectives

Coronary artery bypass grafting (CABG) is associated with better survival than percutaneous coronary intervention (PCI) in patients with mild-to-moderate chronic kidney disease (CKD) and End-Stage Renal Disease (ESRD). However, the optimal strategy for coronary artery revascularization in advanced CKD patients who transition to ESRD is unclear.

Methods

We examined a contemporary national cohort of 971 US veterans with incident ESRD, who underwent first CABG or PCI up to 5 years prior to dialysis initiation. We examined the association of a history of CABG versus PCI with all-cause mortality following transition to dialysis, using Cox proportional hazards models adjusted for time between procedure and dialysis initiation, socio-demographics, comorbidities and medications.

Results

582 patients underwent CABG and 389 patients underwent PCI. The mean age was 66±8 years, 99% of patients were male, 79% were white, 19% were African Americans, and 84% were diabetics. The all-cause post-dialysis mortality rates after CABG and PCI were 229/1000 patient-years (PY) [95% CI: 205-256] and 311/1000PY [95% CI: 272-356], respectively. Compared to PCI, patients who underwent CABG had 34% lower risk of death [multivariable adjusted Hazard Ratio (95% CI) 0.66 (0.51-0.86), p=0.002] after initiation of dialysis. Results were similar in all subgroups of patients stratified by age, race, type of intervention, presence/absence of myocardial infarction, congestive heart failure and diabetes.

Conclusion

CABG in advanced CKD patients was associated lower risk of death after initiation of dialysis compared to PCI.

Objectives

Coronary artery bypass grafting (CABG) is associated with better survival than percutaneous coronary intervention (PCI) in patients with mild-to-moderate chronic kidney disease (CKD) and End-Stage Renal Disease (ESRD). However, the optimal strategy for coronary artery revascularization in advanced CKD patients who transition to ESRD is unclear.

Methods

We examined a contemporary national cohort of 971 US veterans with incident ESRD, who underwent first CABG or PCI up to 5 years prior to dialysis initiation. We examined the association of a history of CABG versus PCI with all-cause mortality following transition to dialysis, using Cox proportional hazards models adjusted for time between procedure and dialysis initiation, socio-demographics, comorbidities and medications.

Results

582 patients underwent CABG and 389 patients underwent PCI. The mean age was 66±8 years, 99% of patients were male, 79% were white, 19% were African Americans, and 84% were diabetics. The all-cause post-dialysis mortality rates after CABG and PCI were 229/1000 patient-years (PY) [95% CI: 205-256] and 311/1000PY [95% CI: 272-356], respectively. Compared to PCI, patients who underwent CABG had 34% lower risk of death [multivariable adjusted Hazard Ratio (95% CI) 0.66 (0.51-0.86), p=0.002] after initiation of dialysis. Results were similar in all subgroups of patients stratified by age, race, type of intervention, presence/absence of myocardial infarction, congestive heart failure and diabetes.

Conclusion

CABG in advanced CKD patients was associated lower risk of death after initiation of dialysis compared to PCI.

Background

Previous studies reported that compared with percutaneous coronary interventions (PCIs), coronary artery bypass grafting (CABG) is associated with a reduced risk of mortality and repeat revascularization in patients with mild to moderate chronic kidney disease (CKD) and end-stage renal disease (ESRD). Information about outcomes associated with CABG versus PCI in patients with advanced stages of CKD is limited. We evaluated the incidence and relative risk of acute kidney injury (AKI) associated with CABG versus PCI in patients with advanced CKD.

Methods

We examined 730 US veterans with incident ESRD who underwent a first CABG or PCI up to 5 years prior to dialysis initiation. The association of CABG versus PCI with AKI was examined in multivariable adjusted logistic regression analyses.

Results

A total of 466 patients underwent CABG and 264 patients underwent PCI. The mean age was 64 ± 8 years, 99% were male, 20% were African American and 84% were diabetic. The incidence of AKI in the CABG versus PCI group was 67% versus 31%, respectively (P < 0.001). The incidence of all stages of AKI were higher after CABG compared with PCI. CABG was associated with a 4.5-fold higher crude risk of AKI {odds ratio [OR] 4.53 [95% confidence interval (CI) 3.28-6.27]; P < 0.001}, which remained significant after multivariable adjustments [OR 3.50 (95% CI 2.03-6.02); P < 0.001].

Conclusion

CABG was associated with a 4.5-fold higher risk of AKI compared with PCI in patients with advanced CKD. Despite other benefits of CABG over PCI, the extremely high risk of AKI associated with CABG should be considered in this vulnerable population when deciding on the optimal revascularization strategy.

AKI, a frequently transient condition, is not accepted by the US Food and Drug Association as an end point for drug registration trials. We assessed whether an intermediate-term change in eGFR after AKI has a sufficiently strong relationship with subsequent ESRD to serve as an alternative end point in trials of AKI prevention and/or treatment. Among 161,185 United States veterans undergoing major surgery between 2004 and 2011, we characterized in-hospital AKI by Kidney Disease Improving Global Outcomes creatinine criteria and decline in eGFR from prehospitalization to postdischarge time points and quantified associations of these values with ESRD and mortality over a median of 3.8 years. An eGFR decline of ≥30% at 30, 60, and 90 days after discharge occurred in 3.1%, 2.5%, and 2.6%, of survivors without AKI and 15.9%, 12.2%, and 11.7%, of survivors with AKI. For patients with in-hospital AKI compared with those with no AKI and stable eGFR, a 30% decline in eGFR at 30, 60, and 90 days after discharge demonstrated adjusted hazard ratios (95% confidence intervals) of ESRD of 5.60 (4.06 to 7.71), 6.42 (4.76 to 8.65), and 7.27 (5.14 to 10.27), with corresponding estimates for 40% decline in eGFR of 6.98 (5.21 to 9.35), 8.03 (6.11 to 10.56), and 10.95 (8.10 to 14.82). Risks for mortality were smaller but consistent in direction. A 30%-40% decline in eGFR after AKI could be a surrogate end point for ESRD in trials of AKI prevention and/or treatment, but additional trial evidence is needed.