Effect Of Preoperative Anemia Research Articles

Prevalence of anemia and association with outcome in joint arthroplasty - is there a difference between primary and revision cases?

Anemia has been shown to be a modifiable pre-operative, patient factor associated with outcome following arthroplasty. The aims of this retrospective study were to (1) ascertain the prevalence of preoperative anemia in patients undergoing primary and revision hip and knee arthroplasty at a tertiary referral center and (2) to test the association with outcome and whether it differs between primary and revision cases. All hip and knee primary and revision arthroplasties performed at a Canadian academic, tertiary-care, arthroplasty center between 2012 and 2017 were included in this study. The study group consisted of 5944 patients, of which 5251 were primary Total Hip and Knee Arthroplasties or Hip Resurfacings and 693 were revision arthroplasties (65% hip revisions/35% knee revisions). Anemia was classified as per WHO definition (hemoglobin < 130g/L for men and < 120g/L for women). All anemic patients were grouped into mild, moderate or severe anemia. Length-of-stay, perioperative transfusion-rate, 90-day readmission, overall complication rate and reoperation rates were recorded. The effect of preoperative anemia and the effect of severity of the anemia was evaluated through multivariable regression analysis controlling for relevant covariates. Preoperatively, 15% (786/5251) of the primary patients and 47% (322/693) of the revision arthroplasty patients were anemic preoperatively. Anemic revision patients were 3.1 times more likely (95% CI: 1.47-6.33) to obtain blood transfusions during the hospital stay, compared to a 4.9 times higher risk in primary patients. The odds ratio to sustain any postoperative complication if anemic was 1.5 times higher (95% CI: 0.73-3.16) in revision patients and 1.7 in primary cases. In addition, the 90-day readmission rate among both groups was 1.6 times higher in anemic patients. Furthermore, anemic revision patients had a 5.3 days longer length of stay (95% CI: 2.63-7.91), compared to only 1 additional day in anemic primary patients (95% CI: 0.69-1.34). In this study cohort, the prevalence of anemia in patients awaiting revision arthroplasty was 3 times higher (46.6%) than in primary arthroplasty patients (18.7%). Preoperative anemia was associated with similarly, inferior outcomes in both groups. To reduce postoperative complications and the "burden" associated with anemia, these findings strongly recommend optimizing the preoperative hemoglobin in all arthroplasty patients. However, revision patients are affected more frequently, and particular attention must therefore be taken to this growing group in the future. Level III.

The Effect of Pre-Operative Anaemia On Patient Outcomes After Surgical Revascularisation For PAD

Objective: Anaemia in patients undergoing surgery is associated with adverse peri-operative outcomes and mortality.1,2 However, the effect of anaemia on vascular specific outcomes such as amputation has not been evaluated in large studies. The purpose of this study was to explore the association between the presence of pre-operative anaemia and post-operative outcomes after surgical revascularisation for peripheral arterial disease (PAD), using National Vascular Registry (NVR) and linked administrative data.

Preoperative anemia in gynecologic oncology surgery: Analysis of the National Surgical Quality Improvement Program Database.

e13528 Background: Preoperative anemia has been identified as risk factor for adverse postoperative outcomes following hysterectomy for benign indications. However, studies have not yet been performed looking at the effect of preoperative anemia on women undergoing surgery for a gynecologic malignancy. Methods: We used the National Surgical Quality Improvement Program data from 2014 to 2019 to conduct a retrospective, population-based cohort study. Our exposure of interest was preoperative anemia, defined as a hemoglobin value &lt;12 g/dL and stratified using the National Cancer Institute grading system. We preformed a logistic regression was used to calculate the adjusted odds ratio evaluate the effect of anemia on the outcomes. Results: Of the 54,569 women in the cohort, 13,232 (24.2%) had anemia. Conclusions: Preoperative anemia, at any grade, is associate with an increase in postoperative morbidity and that the effect is increased with worsening grade of anemia.[Table: see text]

Preoperative Anemia and Risk for Perioperative Neurocognitive Dysfunction in Cardiac Surgery Patients: A Retrospective Analysis

To evaluate whether there is a relationship between preoperative anemia and domain-specific cognitive performance in patients undergoing cardiac surgery. Retrospective analysis of data collected from a randomized study. Tertiary care university hospital. A total of 436 patients age ≥55 years undergoing cardiac surgery. None. Neuropsychological testing was performed before and one month after surgery, using a standard battery. Individual Z-scores calculated from the mean and standard deviation of tests at baseline were combined into domain-specific scores. Anemia (hemoglobin <130 g/L for men, <120 g/L for women) was present in 41% of patients. Preoperative anemia had little impact on preoperative cognition. There were no differences in the change in cognitive performance one month after surgery from baseline between patients with and without preoperative anemia. However, in a sensitivity analysis using multiple imputation for missing cognitive test scores, significant associations were observed between preoperative anemia and change in postoperative processing speed (p=0.016), change in executive function (p=0.049), and change in fine motor speed (p=0.016). Nadir hemoglobin during cardiopulmonary bypass, which was lower in anemic than nonanemic patients, was associated with decrements in performance on tests of verbal fluency (p=0.007), processing speed (p=0.042), and executive function (p=0.10) one month after surgery but not delayed neurocognitive recovery (p=0.06). Preoperative anemia may be associated with impairment of selective cognitive domains after surgery. Any effect of preoperative anemia may have on cognition after surgery might be related to lower nadir hemoglobin during cardiopulmonary bypass.

Preoperative Anemia in Primary Arthroplasty Patients—Prevalence, Influence on Outcome, and the Effect of Treatment

BackgroundThis study aims to: 1) Determine the prevalence of preoperative anemia in arthroplasty; 2) Assess whether preoperative anemia is associated with inferior outcomes; and 3) Ascertain whether optimization in a dedicated blood management program (BMP) is associated with improved outcomes. MethodsAll primary arthroplasties performed at an academic, tertiary-care, arthroplasty center between 2012 and 2017 were reviewed. Hemoglobin level obtained in the preoperative assessment clinic was recorded. Patients with anemia were then considered for further review in BMP. Outcomes included improvement in hemoglobin level post-BMP; length of stay; perioperative transfusion; 90-day readmission, complication, and reoperation rates. The effect of preoperative anemia and the effect of treatment at the BMP on outcomes were evaluated through multivariable regression analysis controlling for relevant covariates. Results17% of patients (932/5384) were found to have anemia; 115/357 patients who attended the BMP were no longer anemic. Thus, at time of operation, 15% of patients (817/5384) had anemia. Anemic patients were 4.09 times more likely (95% CI: 2.64-6.35) to require a transfusion; 1.42 times more likely (95% CI: 0.99-2.03) to sustain complications and had 19% longer (95% CI: 13%-26%) length of stay.Those who attended the BMP were less likely to receive a transfusion (OR = 0.32, 95% CI: 0.16-0.66), suffer from postoperative complications (OR = 0.30, 95% CI: 0.14-0.63), or require readmission compared with anemic patients not seen in the BMP (OR = 0.25, 95% CI: 0.09-0.71). ConclusionsThe prevalence of anemia in this arthroplasty cohort was 15%. Preoperative, timely, optimization of anemia should be strongly considered as it is likely to reduce “anemia-associated burden” after arthroplasty.

The impact of preoperative anemia on red blood cell transfusion in primary and revision hip arthroplasty: A retrospective analysis

Rationale: Lower extremity joint arthroplasty can lead to significant blood loss, and the need for blood transfusion. The use of blood products is associated with a variety of adverse outcomes including infection, circulatory overload, and transfusion reaction. Objectives: The objective of this quality improvement study is to identify the prevalence of preoperative anemia at our institution, and elucidate its impact on perioperative transfusion in elective patients undergoing primary or revision hip arthroplasty. Methods: Data for this study was collected from four databases at our institution. Elective patients undergoing primary or revision hip arthroplasty were selected. Transfusion was defined as the receipt of a red blood cell transfusion on the surgical day through to postoperative day five. The primary outcome was the effect of preoperative anemia on transfusion rates. Results: The overall transfusion rate was 7.6%. Transfusion rates for primary and revision arthroplasty were 5.8% and 18.7% respectively. Patients with a preoperative hemoglobin between 100 and 120 g/L were 4.5 times more likely to be transfused than those with a hemoglobin between 121 and 140 g/L, and 15.4 times more likely than those greater than 140 g/L. Preoperative anemia was common, with 11.5% of all patients having a preoperative hemoglobin of 120 g/L or less. Conclusion: Preoperative anemia was common and was significantly associated with higher transfusion rates. These findings reinforce the need to optimize hip arthroplasty patients prior to surgery, where possible. As a quality control study, these findings may help direct policy regarding the deferral of elective hip arthroplasty patients who are anemic preoperatively.

The Effect of Preoperative Anemia on Complications After Total Hip Arthroplasty

BackgroundCurrent literature suggests that preoperative hematocrit levels may play an important role in determining risk for complications after total hip arthroplasty (THA). The purpose of this study was to determine the role of preoperative anemia status on 30-day complications after THA. MethodsUsing the National Surgical Quality Improvement Program registry from 2006 to 2016, we identified all patients who underwent primary THA. Patients were placed into 3 cohorts based on preoperative hematocrit levels (normal > 36% [N = 166,538], mild anemia 27%-36% [N = 13,214], and severe anemia <27% [N = 541]). Differences in 30-day postoperative medical complications and readmission rates were compared using bivariate and multivariate analyses. ResultsMultivariate logistic regression analysis identified mild anemia compared with normal hematocrit as a significant risk factor for total complications (OR: 1.46, P < .001), mortality (OR: 2.06, P < .001), renal complications (OR: 2.59, P < .001), respiratory complications (OR: 1.89, P < .001), sepsis (OR: 2.01, P < .001), wound infection (OR: 1.36, P < .001), and urinary tract infection (OR: 1.44, P < .001). Severe anemia was also risk factor, with a higher odds ratio, for total complications (OR: 1.99, P < .001). Both mild and severe anemia were significant risk factors for increased rates of perioperative blood transfusion (mild: OR, 4.04, severe: OR, 5.58), nonhome discharge (OR: 1.74, OR: 1.64), and unplanned hospital readmissions (OR: 1.42, OR: 1.66). ConclusionPreoperative anemia is a significant risk for perioperative complications after primary THA. Even mild anemia can lead to significantly increased risks of mortality, medical complications, and unplanned hospital readmissions in THA. This study further supports the need for screening and preoperative intervention for patients in this at-risk group.

The Effect of Preoperative Anemia on Patients Undergoing Cardiac Surgery: A Propensity-Matched Analysis

It is unknown if anemia in the absence of transfusions is an independent risk factor for adverse outcomes in cardiac surgery, and if correction to higher hemoglobin targets impacts these outcomes. This is a retrospective review of 3848 cardiac surgery patients. Propensity matching was completed using 41 covariates. Intraoperative Anemia Analysis matched patients with or without anemia who did not receive intraoperative transfusions (n = 392/group), while Intraoperative Transfusion Analysis matched anemic patients treated conventionally with intraoperative transfusions to end cardiopulmonary bypass hemoglobin greater or less than 95 g/L (n = 261/group). Outcomes of death, renal failure, and 2 composite outcomes were assessed using paired analysis techniques. Study composite 1 consisted of prolonged ventilation, renal failure, myocardial infarction, stroke, or deep sternal wound infection, while composite 2 was the TRICS-III composite. In the Intraoperative Anemia Analysis, anemia was associated with mortality (P = 0.034), stroke (P = 0.021), renal failure (P = 0.015), and a significant increase in the composite measure (control 8.7% vs anemia 16.1%, P = 0.002). These findings were unchanged in patients who did not receive any postoperative transfusions. The Intraoperative Transfusion Analysis showed no difference in mortality or the composite outcome between groups. There was a significant increase in low cardiac output in the lower threshold group (P = 0.001). There were no differences in outcomes between those who did and did not receive postoperative transfusions (P > 0.05). Preoperative anemia in the absence of transfusions is a risk factor for morbidity and mortality after cardiac surgery, and there is no evidence that transfusion to higher end cardiopulmonary bypass hemoglobin levels impacted this risk.

Assessing Effects of Preoperative Anemia on Adverse Outcomes After Coronary Surgery

Assessing Effects of Preoperative Anemia on Adverse Outcomes After Coronary Surgery

Effect of Preoperative Anemia on the Outcomes of Anterior Cervical Discectomy and Fusion.

Study Design:Retrospective cohort study.Objective:Preoperative anemia has been associated with an increased need for blood transfusions and postoperative complications. The effects of anemia on the outcomes of anterior cervical discectomy and fusion (ACDF) have not been explored. The present study aimed to evaluate the association between preoperative anemia and 30-day complications following ACDF surgery.Methods:Data from the American College of Surgeons National Surgical Quality Improvement Program (2005-2012) was used. Preoperative anemia was defined as hematocrit <39% for males and <36% for females. A bivariate analysis was performed on demographic and perioperative variables. Multivariable logistic regression models were employed, adjusting for patient variables, to identify independent risk factors for complications.Results:A total of 3500 patients were included of which 444 (12.7%) were anemic patients. Multivariate analysis was used to quantify the predictive power of anemia on key postoperative outcomes, while controlling for the other statistically significant. Preoperative anemia was found to be a statistically significant predictor of any complication (odds ratio [OR] = 1.853; 95% confidence interval [CI] = 1.17-2.934; P = .0086), pulmonary complications (OR = 3.269; 95% CI = 1.745-6.126; P = .0002), intraoperative blood transfusion (OR = 4.364; 95% CI = 1.48-12.866; P = 0.0076), return to operating theatre (OR = 2.655; 95% CI = 1.539-4.582; P = .0005), and length of hospital stay more than 5 days (OR = 2.151; 95% CI = 1.499-3.085; P < .0001).Conclusion:Preoperative anemia appears to be a significant predictor of perioperative complications, reoperation, and extended length of hospital stay in patients undergoing elective ACDF. Future studies should explore outcomes of treatment of preoperative anemia prior to surgery to determine the optimal management strategy.

The Effect of Preoperative Anemia on the Outcome After Coronary Surgery.

Preoperative anemia is associated with increased morbidity and mortality after cardiac surgery. Since anemia is ultimately treated with red blood cell transfusions, we investigated the independent impact of anemia and transfusion on the outcome after coronary artery bypass grafting (CABG). This study included 2761 consecutive patients who underwent isolated CABG. Anemia was defined as hemoglobin <12.0g/dL in women and <13.0g/dL in men. The main outcomes were 30-day and late mortality. Patients with preoperative anemia had an increased prevalence of significant comorbidities and were associated with higher unadjusted risk of early and late adverse events. Propensity score matching resulted in 560 pairs with similar baseline and operative characteristics. In these matched pairs, anemic patients had an increased risk of late all-cause death (P=0.047) and acute kidney injury (P<0.0001). However, when adjusted for the severity of perioperative bleeding, preoperative anemia was not associated with an increased mortality risk (HR 1.10, 95% CI 0.86-1.39). Instead, this regression model showed that the European CABG registry (E-CABG) bleeding classification was an independent predictor of late mortality (compared to grade 0: grade 1, HR 1.93, 95% CI 1.37-2.73, grade 2, HR 2.19, 95% CI 1.50-3.18, grade 3, HR 5.59, 95% CI 3.34-9.39, P<0.0001). When adjusted for important baseline characteristics and operative factors as well as for the severity of perioperative bleeding and the amount of transfused blood products, anemia was not associated with an increased risk of adverse events. Increased exposure to blood transfusion among anemic patients may be the determinant of their poorer late survival.

Pre-operative anaemia is associated with total morbidity burden on days 3 and 5 after cardiac surgery: a cohort study

BackgroundPre-operative anaemia is associated with mortality and red blood cell (RBC) transfusion requirement after cardiac surgery. However, the effect on post-operative total morbidity burden (TMB) is unknown. We explored the effect of pre-operative anaemia on post-operative TMB.MethodsData were drawn from the Cardiac Post-Operative Morbidity Score (C-POMS) development study (n = 442). C-POMS describes and quantifies (0–13) TMB after cardiac surgery by noting the presence/absence of 13 morbidity domains on days 3 (D3), 5 (D5), 8 (D8) and 15 (D15). Anaemia was defined as a haemoglobin concentration below 130 g/l for men and 120 g/l for women.ResultsMost patients were White British (86.1%) and male (79.2%) and underwent coronary artery bypass surgery (67.4%). Participants with pre-operative anaemia (n = 137, 31.5%) were over three times more likely to receive RBC transfusion (OR 3.08, 95%CI 1.88–5.06, p < 0.001), had greater D3 and D5 TMB (5 vs 3, p < 0.0001; 3 vs 2, p < 0.0001, respectively) and remained in hospital 2 days longer (8 vs 6 days, p < 0.0001) than non-anaemic patients. Transfused patients remained in hospital 5 days longer than non-transfused patients (p < 0.0001), had higher TMB on all days (all p < 0.001) and suffered greater pulmonary, renal, GI, neurological, endocrine and ambulation morbidities (p 0.026 to <0.001). Pre-operative anaemia and RBC transfusion were independently associated with increased C-POMS score.ConclusionsPre-operative anaemia and RBC transfusion are independently associated with increased post-operative TMB. Understanding TMB may assist in post-operative patient management to reduce morbidity. We recommend the use of the C-POMS tool as a standard outcome tool in further studies.

Effect of Pre-operative Anaemia on Post-operative Complications in Low-Resource Settings.

In high-resource settings, even mild anaemia is associated with an increased risk of post-operative complications. Whether this is true in low-resource settings is unclear. We aimed to evaluate the effect of anaemia on surgical outcomes in the Republic of Congo and Madagascar. It is a retrospective chart review of 2064 non-pregnant patients undergoing elective surgery with Mercy Ships. Logistic regression was used to determine the association between pre-operative anaemia and pre-defined surgical complications, adjusted for age, gender, surgical specialty, and country. The average age of patients was 27.2years; 56.7% were male. Sixty-two percent of patients were not anaemic, and 22.7, 13.9 and 1.4% met sex-related criteria for mild, moderate and severe anaemia, respectively. In adjusted analyses, the severe anaemia group had an 8.58 [3.65, 19.49] higher odds of experiencing any surgical complication (p<0.001) compared to non-anaemic patients. Analysis of each complication showed a 33.13 [9.57, 110.39] higher odds of unexpected ICU admission (p<0.001); a 7.29 [1.98, 21.45] higher odds of surgical site infection (p<0.001); and 7.48 [1.79, 25.78] higher odds of requiring hospital readmission (p<0.001). Evaluating other anaemia categories, only those with moderate anaemia had a higher risk of requiring ICU admission (odds ratio 2.75 [1.00, 7.04], p=0.04) compared to those without anaemia. Our results indicate that in low-income settings, severe anaemia is associated with an increased risk of post-operative complications including unexpected ICU admission, surgical site infection and hospital readmission, whereas mild anaemia was not associated with increased post-operative complications.

Preoperative anemia and postoperative outcomes after hepatectomy

BackgroundPreoperative anaemia is associated with adverse outcomes after surgery but outcomes after liver surgery specifically are not well established. We aimed to analyze the incidence of and effects of preoperative anemia on morbidity and mortality in patients undergoing liver resection. MethodsAll elective hepatectomies performed for the period 2005–2012 recorded in the American College of Surgeons' National Surgical Quality Improvement Program (ACS-NSQIP) database were evaluated. We obtained anonymized data for 30-day mortality and major morbidity (one or more major complication), demographics, and preoperative and perioperative risk factors. We used multivariable logistic regression models to assess the adjusted effect of anemia, which was defined as (hematocrit <39% in men, <36% in women), on postoperative outcomes. ResultsWe obtained data for 12,987 patients, of whom 4260 (32.8%) had preoperative anemia. Patients with preoperative anemia experienced higher postoperative major morbidity and mortality rates compared to those without anemia. After adjustment for predefined variables, preoperative anemia was an independent risk factor for postoperative major morbidity (adjusted OR 1.21, 1.09–1.33). After adjustment, there was no significant difference in postoperative mortality for patients with or without preoperative anemia (adjusted OR 0.88, 0.66–1.16). ConclusionPreoperative anemia is independently associated with an increased risk of major morbidity in patients undergoing hepatectomy. Therefore, it is crucial to readdress preoperative blood management in anemic patients prior to hepatectomy.

Prognostic effect of preoperative anemia in patients who have undergone radical cystectomy for bladder cancer

Abstract Objective In this study, we aimed to investigate the prognostic significance of preoperative anemia in bladder cancer patients who have undergone radical cystectomy. Materials and methods Data of 148 patients were collected, who underwent radical cystectomy with or without neoadjuvant chemotherapy for bladder cancer. Preoperative hemoglobin levels of these patients were measured and then classified as normal or anemia. Hemoglobin threshold value of the patients in the study was taken as the average of all patients. The results were assessed by using the univariate and multivariate analyses. Results The mean preoperative hemoglobin value was 12.2g/dl (6.9–16). With reference to the specified threshold hemoglobin value (12.2g/dl), 70 patients were anemic. Cancer-specific survival was found significantly lower in patients with low preoperative hemoglobin value, as determined by univariate analysis. After an average follow-up period of 21.1 months, anemia was found to be associated with decreased cancer-specific survival. Low preoperative hemoglobin value is an independent risk factor for shorter cancer-specific survival. Conclusion Preoperative anemia is an independent risk factor for cancer-specific survival. This is associated with aggressive tumor structure of patients with bladder cancer who underwent radical cystectomy. Hemoglobin value is an important marker that can be used to determine the prognosis in these patients.

Prevalence and effects of pre-operative anemia on short- and long-term mortality in patients undergoing transcatheter aortic valve implantation

Prevalence and effects of pre-operative anemia on short- and long-term mortality in patients undergoing transcatheter aortic valve implantation

Reply to Balta et al.

We thank Balta et al. [1] for their interest in our article: preoperative anaemia is a risk factor for mortality and morbidity following aortic valve surgery [2] and for the interesting points they raised. Balta et al. are in agreement that preoperative anaemia is a common finding and an important risk factor for morbidity and mortality in patients undergoing aortic valve surgery. We disagree with their assertion that blood transfusion is ‘dangerous’. In fact, blood transfusions can be life-saving and make surgery possible in many patients who would otherwise not be candidates for cardiac surgery. It is more likely that the pre-existing conditions that lead to blood transfusion (i.e. preoperative anaemia, excessive bleeding and haemodilution) are likely associated with worse outcome [3, 4]. In our study, red blood cell distribution width was not routinely measured. However, it is unlikely that this would have a significant impact on the primary message of this study. Pre-existing renal dysfunction (as measure by estimated glomerular filtration rate) was incorporated in our multivariable model and was adjusted in this study. Balta et al. also commented that we should define ‘how much time [we] specified on measuring haemoglobin levels’. If the authors mean which preoperative haemoglobin was used to define preoperative anaemia, in our study we used the latest available laboratory result for haemoglobin before surgery to define anaemia. For in-hospital patients, this was the day before the surgery and for elective patients the haemoglobin measurement was typically within 2 weeks of their surgery date. As noted in the study, preoperative anaemia was defined as per World Health Organization guidelines. Finally, we agree with the authors that further studies are warranted to better understand the mechanism and effect of preoperative anaemia on outcome after cardiac surgery.

Hematocrit Level and Postsurgical Outcome

Context Elderly patients are at high risk of both abnormal hematocrit values and cardiovascular complications of noncardiac surgery. Despite nearly universal screening of patients for abnormal preoperative hematocrit levels, limited evidence demonstrates the adverse effects of preoperative anemia or polycythemia. Objective To evaluate the prevalence of preoperative anemia and polycythemia and their effects on 30-day postoperative outcomes in elderly veterans undergoing major noncardiac surgery. Design Retrospective cohort study using the VA National Surgical Quality Improvement Program database. Based on preoperative hematocrit levels, we stratified patients into standard categories of anemia (hematocrit 54%). We then estimated increases in 30-day postoperative cardiac event and mortality risks in relation to each hematocrit point deviation from the normal category. Setting and Patients A total of 310 311 veterans aged 65 years or older who underwent major noncardiac surgery between 1997 and 2004 in 132 Veterans' Affairs medical centers across the United States. Main Outcome Measures The primary outcome measure was 30-day postoperative mortality; a secondary outcome measure was composite 30-day postoperative mortality or cardiac events (cardiac arrest or Q-wave myocardial infarction). Results Thirty-day mortality and cardiac event rates increased monotonically, with either positive or negative deviations from normal hematocrit levels. We found a 1.6% (95% confidence interval, 1.1 %-2.2%) increase in 30-day postoperative mortality associated with every percentage-point increase or decrease in the hematocrit value from the normal range. Additional analyses suggest that the adjusted risk of 30-day postoperative mortality and cardiac morbidity begins to rise when hematocrit levels decrease to less than 39% or exceed 51 %. Conclusions Even mild degrees of preoperative anemia or polycythemia were associated with an increased risk of 30-day postoperative mortality and cardiac events in older, mostly male veterans undergoing major noncardiac surgery. Future studies should determine whether these findings are reproducible in other populations and if preoperative management of anemia or polycythemia decreases the risk of postoperative mortality.