Red cell distribution width in chronic heart failure: a new independent marker for prognosis?

Association between Red Blood Cell Distribution Width and In-Hospital Mortality among Congestive Heart Failure Patients with Diabetes among Patients in the Intensive Care Unit: A Retrospective Cohort Study

Background

Elevated red blood cell distribution width (RDW) levels are strongly associated with an increased risk of mortality in patients with congestive heart failure (CHF). Additionally, heart failure has been closely linked to diabetes. Nevertheless, the relationship between RDW and in-hospital mortality in the intensive care unit (ICU) among patients with both congestive heart failure (CHF) and diabetes mellitus (DM) remains uncertain.

Methods

This retrospective study utilized data from the Medical Information Mart for Intensive Care IV (MIMIC-IV) database, a comprehensive critical care repository. RDW was assessed as both continuous and categorical variables. The primary outcome of the study was in-hospital mortality at the time of hospital discharge. We examined the association between RDW on ICU admission and in-hospital mortality using multivariable logistic regression models, restricted cubic spline analysis, and subgroup analysis.

Results

The cohort consisted of 7,063 patients with both DM and CHF (3,135 females and 3,928 males). After adjusting for potential confounders, we found an association between a 9% increase in mortality rate and a 1 g/L increase in RDW level (OR = 1.09; 95% CI, 1.05∼1.13), which was associated with 11 and 58% increases in mortality rates in Q2 (OR = 1.11, 95% CI: 0.87∼1.43) and Q3 (OR = 1.58, 95% CI: 1.22∼2.04), respectively, compared with that in Q1. Moreover, we observed a significant linear association between RDW and in-hospital mortality, along with strong stratified analyses to support the findings.

Conclusions

Our findings establish a positive association between RDW and in-hospital mortality in patients with DM and CHF.

Association of D-dimer to albumin ratio with adverse cardiovascular outcomes in ischaemic heart failure patients with diabetes mellitus: a retrospective cohort study

OBJECTIVE

To determine the association of D-dimer to albumin ratio (DAR) with major adverse cardiovascular events (MACE) after percutaneous coronary intervention (PCI) in ischaemic heart failure patients with diabetes mellitus.

DESIGN

A retrospective observational cohort study.

SETTING

Single centre in Beijing, China, conducted at one of the largest cardiology centres in China.

PARTICIPANTS

From June 2017 to June 2019, 3707 patients with heart failure and concomitant multiple vessel disease undergoing elective PCI were screened. A total 1021 of patients were enrolled after exclusion and the follow-up period was up to 36 months.

PRIMARY AND SECONDARY OUTCOME MEASURES

The MACE was the primary measured outcome. The secondary outcomes were all-cause mortality, non-fatal myocardial infarction and any revascularisation.

METHODS

These participants were grouped according to DAR tertiles. The cumulative incidence functions, Cox regression, restricted cubic spline and receiver operating characteristic curves were used to determine the association between DAR and outcomes. The subgroup analysis was also performed.

RESULTS

After follow-up, MACE occurred in 404 (39.6%) participants. The cumulative hazards curve manifested significant differences in MACE, all-cause mortality and any revascularisation (log-rank test: all p<0.001). In adjusted models, DAR was an independent risk factor of MACE (tertile 2: HR 1.82, 95% CI 1.37 to 2.42; tertile 3: HR 1.74, 95% CI 1.28 to 2.36) and all-cause mortality (tertile 2: HR 2.04, 95% CI 1.35 to 3.11; tertile 3: HR 1.89, 95% CI 1.20 to 2.98). The optimal cut-off of DAR was 1.2. In the stratified analysis, sex, age, hypertension, hypercholesterolaemia, total revascularisation and any interfered vessel did not affect the independent predictive ability.

CONCLUSION

Higher DAR was independently associated with MACE and all-cause mortality after PCI in ischaemic heart failure patients with diabetes mellitus.

Association between red blood cell distribution width to albumin ratio and prognosis of patients with sepsis: A retrospective cohort study

Background

Red blood cell distribution width (RDW) to albumin ratio (RAR) is associated with poor prognosis in diabetic comorbidities and cancer. However, the association between RAR and prognosis in patients with sepsis remains unclear, which was investigated in this study.

Methods

We conducted a retrospective cohort study based on the Medical Information Mart for Intensive Care (MIMIC) IV version 2.0 database. The primary outcome of this study was 28-day mortality. Secondary outcomes included 90-day mortality, in-hospital mortality, length of hospital stay, and length of intensive care unit (ICU) stay. Multivariate regression analysis and subgroup analysis were performed to investigate the association between RAR and prognosis in patients with sepsis.

Results

A total of 14,639 participants were included in this study. The mean age of the participants was 65.2 ± 16.3 years and the mean RAR was 5.5 ± 1.9 % /g/dl. For 28-day mortality, after adjusting for covariates, HRs [95% confidence intervals (CIs)] for tertiles 2 (4.4–5.8) and 3 (RAR > 5.8) were 1.33 (1.20, 1.46) and 1.98 (1.79, 2.19), respectively. Similar results were observed for 90-day mortality and in-hospital mortality. According to Kaplan-Meier curve analysis, the higher RAR group had higher 28-day mortality and 90-day mortality.

Conclusion

Our study shows that RAR is significantly associated with poor clinical prognosis in sepsis. The higher the RAR, the higher the 28-day, 90-day, and in-hospital mortality.

Red Blood Cell Distribution Width (RDW) as a Predictor of In-Hospital Mortality in COVID-19 Patients; a Cross Sectional Study

INTRODUCTION

Red blood cell distribution width (RDW) has been introduced as a predictive factor for mortality in several critical illnesses and infectious diseases. This study aimed to assess the possible relationship between RDW on admission and COVID-19 in-hospital mortality.

METHOD

This cross-sectional study was performed using the Isfahan COVID-19 registry. Adult confirmed cases of COVID-19 admitted to four hospitals affiliated with Isfahan University of Medical Sciences in Iran were included. Age, sex, O2 saturation, RDW on admission, Intensive Care Unit admission, laboratory data, history of comorbidities, and hospital outcome were extracted from the registry. Cox proportional hazard regression was used to study the independent association of RDW with mortality.

RESULTS

4152 patients with the mean age of 61.1 ± 16.97 years were included (56.2% male). 597 (14.4%) cases were admitted to intensive care unit (ICU) and 477 (11.5%) cases died. The mortality rate of patients with normal and elevated RDW was 7.8% and 21.2%, respectively (OR= 3.1, 95%CI: 2.6-3.8), which remained statistically significant after adjusting for age, O2 saturation, comorbidities, and ICU admission (2.03, 95% CI: 1.68-2.44). Moreover, elevated RDW mortality Hazard Ratio in patients who were not admitted to ICU was higher than ICU-admitted patients (3.10, 95% CI: 2.35-4.09 vs. 1.47, 95% CI: 1.15-1.88, respectively).

CONCLUSION

The results support the presence of an association between elevated RDW and mortality in patients with COVID-19, especially those who were not admitted to ICU. It seems that elevated RDW can be used as a predictor of mortality in COVID-19 cases.

Prognostic Value of Preoperative Red Cell Distribution Width: Fine-Tuning by Mean Corpuscular Volume

BACKGROUND

Abnormal red cell distribution width (RDW), reflecting heterogeneity of red blood cell (RBC) size, is associated with cardiovascular disease outcomes. However, whether RBC size itself, expressed as mean corpuscular volume (MCV), provides additional prognostic value is unclear. We therefore investigated the relationship between outcomes after cardiac surgery and both RDW and MCV simultaneously.

METHODS

From January 2010 to January 2014, 16,097 patients underwent cardiac surgery at Cleveland Clinic and had complete blood count findings available for analysis. Outcomes included RBC transfusion, postoperative complications, and intensive care unit (ICU) and postoperative hospital lengths of stay. Risk-adjusted associations of RDW and MCV with outcomes and their relative importance in predicting outcome were identified by random forest machine learning.

RESULTS

High RDW was associated with more RBC transfusions. Except for postoperative atrial fibrillation, risks of complications and ICU and postoperative lengths of stay were at their minimum when RDW was normal, 13% to 14%. The relationship of MCV to complications was U-shaped: high (macrocytosis) and low (microcytosis) values were associated with higher risk. RDW was an important risk factor for most postoperative outcomes and lengths of stay; MCV was less so, but provided prognostic value in addition to RDW alone, particularly when there was macrocytosis.

CONCLUSIONS

Abnormal RDW and MCV are associated with higher risk of transfusion and postoperative outcomes after cardiac surgery. RDW is one of the most important variables in predicting outcomes, but MCV provides additional prognostic value. Both should be taken into consideration when estimating the perioperative risk of patients undergoing cardiac surgery.

The prognostic value of interaction between mean corpuscular volume and red cell distribution width in mortality in chronic kidney disease

Recently, both red cell distribution width (RDW) and mean corpuscular volume (MCV) have been associated with unfavorable outcomes in several medical conditions. Therefore, we conducted this retrospective study of 1075 patients with stage 3-5 chronic kidney disease to investigate whether interactions between RDW and MCV influence the risk of mortality. These patients were divided into four groups: group A (n = 415), RDW ≤ 14.9% and MCV ≤ 91.6 fL; group B (n = 232), RDW > 14.9% and MCV ≤ 91.6 fL; group C (n = 307), RDW ≤ 14.9% and MCV > 91.6 fL; and group D (n = 121), RDW > 14.9% and MCV > 91.6 fL. The adjusted hazard ratio (HR) of all-cause mortality for group B versus group A was 1.44 (95% confidence interval [CI], 1.14-2.12, p = 0.02), group C versus group A 2.14 (95% CI, 1.31-3.48, p = 0.002), and group D versus group A 5.06 (95% CI, 3.06-8.37, p < 0.001). There was a multiplicative interaction between MCV and RDW in predicting patient mortality. The use of RDW in conjunction with MCV may improve healthcare by identifying those at an increased risk for mortality compared with the use of either RDW or MCV alone.

Prognostic Value of Blood Panel Parameters in Patients With Dilated Cardiomyopathy and Advanced Heart Failure

BACKGROUND

Patients with dilated cardiomyopathy (DCM) and left ventricular dysfunction have a varied clinical course, not only dependent on left ventricular ejection fraction (LVEF) and symptoms. Finding prognostic markers for stratification in these 2 conditions is a critical area of research. Our aim was determine the prognostic value of blood panel basic parameters.

METHODS

We analyzed all patients with idiopathic or familial DCM and LVEF <30% coming to our heart failure unit for evaluation for non-urgent heart transplant during the period of 2009 to 2011. With 5 years of follow-up data, we could study the prognostic value of blood panel parameters. Moreover, we determined the combination of platelet count and neutrophil to lymphocyte ratio score from the BIOSTAT-CHF study.

RESULTS

Eighty-seven patients were included in the study. After 5 years follow-up, 49 patients (57%) remain alive (group A) and 38 (43%) either died or needed a heart transplant. There were no differences between groups with regard to age or sex. Patients with good progress showed a lower red cell distribution width (RDW), a higher lymphocyte count, and a lower neutrophil/lymphocyte ratio in the initial blood panel. An RDW ≥15% was associated with long-term mortality or heart transplant.

CONCLUSION

A basic blood panel could be a useful tool in assessing patients with heart failure. Larger studies are necessary to confirm our findings. A multimarker strategy could also be useful for stratification of patients with advanced heart failure.

Effect of Baseline Red Blood Cell Distribution Width on Short- and Intermediate-term Mortality of Patients Under Primary Percutaneous Coronary Intervention: A Survival Analysis

OBJECTIVE

Considering the limited studies specifically evaluating the role of Red blood cell distribution width (RDW) in primary percutaneous coronary intervention (PCI), we aimed to investigate the role of baseline RDW in short- and intermediate-term cardiovascular events in ST-elevation myocardial infarction patients under primary PCI.

METHODS

This is a historical cohort registry analysis of 1161 patients with ST-elevation myocardial infarction under primary PCI. According to inclusion criteria, 838 patients were allocated for analysis. Patients with RDW levels of 13.6% or higher were considered as high RDW group (third tertile). All the individuals were followed up for in-hospital and 6-month mortality along with readmission and composite major adverse cardiac events.

RESULTS

In-hospital deaths occurred in 53 (6.3%) patients and at 6-month follow-up 79 (9.4%) cases of mortality were documented. In-hospital and 6-month mortalities showed a significant trend in favor of high RDW group (13.3% vs. 5.9%, P = 0.003; 19.7% vs. 7.9%, P < 0.001, respectively). Multivariate analysis showed that high RDW was significantly and independently associated with higher rates of 6-month mortality (hazard ratio: 2.909; 95% confidence interval: 1.166-7.257; P = 0.022). RDW was also a significant predictor for 6-month mortality independent of anemia (hazard ratio: 2.811; 95% confidence interval: 1.047-7.551; P = 0.040).

CONCLUSIONS

We found a significant association between high RDW and in-hospital and 6-month mortality as well as the occurrence of major adverse cardiac event. Meanwhile RDW was found to be a significant predictor for 6-month mortality independent of anemia. Thus, it would be beneficial to use RDW as a risk stratification index to identify high risk intent-to-treat patients.

Red Blood Cell Distribution Width Is Associated with Severity of Leukoaraiosis

Red blood cell distribution width (RDW) is one of the routine hematologic parameters reported in the complete blood count test, which has been recognized as strong prognostic marker for various medical conditions, especially cardiovascular disease. We evaluated that RDW was also associated with the leukoaraiosis; common radiological finding of brain and that has been strongly associated with risk of stroke and dementia. In the present study, we included 1006 non-stroke individuals who underwent brain MRI and routine complete blood count test including RDW. Fazekas scale was used to measure the severity of leukoaraiosis based on fluid-attenuated inversion recovery image, and the severity was dichotomized to mild-degree (Fazekas scale: 0–1) and severe-degree leukoaraiosis (Fazekas scale: 2–3). Univariate and multivariate logistic regression models were constructed to evaluate independent risk factor for severe-degree of leukoaraiosis. Mean age of 1006 subjects was 64.34 ± 9.11 year, and mean of RDW was 12.97 ± 0.86%. The severe-degree of leukoaraiosis (Fazekas scale ≥ 2) was found in 28.83%. In the multivariate logistic regression, 4^th quartile of RDW (> 13.3%) were significantly associated with the presence of severe-degree of leukoaraiosis (adjusted odds ratio, 1.87; 95% confidence interval, 1.20–2.92) compared to the 1^st quartile of RDW (< 12.5%). The significance was not changed after adjustments for hemoglobin and other hematologic indices. These findings suggest that RDW is independently associated with severity of leukoaraiosis.

Evaluation of red cell distribution width in dogs with pulmonary hypertension

OBJECTIVES

To compare red cell distribution width (RDW) between dogs with different causes of pulmonary hypertension (PH) and a control dog population to determine whether RDW was correlated with severity of PH as measured by echocardiography. A further aim was to determine the prognostic significance of increased RDW for dogs with PH.

ANIMALS

Forty-four client-owned dogs with PH and 79 control dogs presented to a single tertiary referral institution.

METHODS

Signalment, clinical pathological and echocardiographic data were obtained retrospectively from the medical records of dogs with PH, and RDW measured on a Cell-Dyn 3500 was compared between dogs with pre- and post-capillary PH and a control population. Referring veterinary surgeons were contacted for follow-up information and Kaplan-Meier analysis was conducted to investigate differences in survival time between affected dogs with different RDW values.

RESULTS

The RDW was significantly greater in dogs with pre-capillary PH compared to control dogs. There was no difference in median survival times between dogs with PH divided according to RDW values. The RDW was positively correlated with mean corpuscular volume and haematocrit in dogs with PH, but did not correlate with echocardiographic variables.

CONCLUSIONS

An association was found between dogs with PH and increased RDW; however there was considerable overlap in values between control dogs and dogs with PH. The RDW was not associated with survival in this study.

Multiplicative interaction between mean corpuscular volume and red cell distribution width in predicting mortality of elderly patients with and without anemia

Recent studies have shown that an elevated red cell distribution width (RDW) is an important predictor of adverse outcomes. However, the strength of this biomarker has not been tested in a large outpatient elderly population. Also since increased RDW can be due to a variety of etiologies, additional biomarkers are needed to refine the prognostic value of this variable. We assembled a cohort of 36,226 elderly (≥65yo) patients seen at an outpatient facility within the Einstein/Montefiore system from January 1st 1997 to May 1st 2008 who also had a complete blood count performed within 3 months of the initial visit. With a maximum follow-up of 10 years, we found that an elevated RDW (>16.6) was associated with increased risk of mortality in both non-anemic (HR = 3.66, p < 0.05) and anemic patients (HR = 1.87, p < 0.05). The effect of RDW on mortality is significantly increased in non-anemic patients with macrocytosis (HR = 5.22, p < 0.05) compared to those with normocytosis (HR = 3.86, p < 0.05) and microcytosis (HR = 2.46, p < 0.05). When comparing non-anemic patients with both an elevated RDW and macrocytosis to those with neither, we observed an elevated HR of 7.76 (higher than expected in an additive model). This multiplicative interaction was not observed in anemic patients (HR = 2.23). Lastly, we constructed Kaplan-Meier curves for each RDW/MCV subgroup and found worsened survival for those with macrocytosis and an elevated RDW in both anemia and non-anemic patients. Based on our results, the addition of MCV appears to improve the prognostic value of RDW as a predictor of overall survival in elderly patients.

Red cell distribution width is associated with physical inactivity and heart failure, independent of established risk factors, inflammation or iron metabolism; the EPIC-Norfolk study

AIMS

Red cell distribution width (RDW) is associated with increased risk of heart failure (HF). We examined in a healthy population (1) whether this association is independent of cardiovascular risk factors and iron metabolism and (2) whether RDW associates with physical activity.

METHODS AND RESULTS

Hazard ratios (HRs, highest quartile versus lowest quartile of RDW) for the risk of HF were calculated in 17,533 participants from the European Prospective Investigation into Cancer and Nutrition (EPIC)-Norfolk cohort. During a follow-up of 11.2±2.2 years 640 participants developed a HF event. The HR for HF events was 1.44 (95%CI 1.15-1.80, p<0.001). There was a non-linear increase in HF risk across RDW quartiles. Adjustment for established risk factors (sex, age, diabetes, smoking, systolic blood pressure, total and high-density lipoprotein cholesterol) attenuated the HR for HF to 1.40 (95%CI 1.11-1.77, p=0.001). Adjustment for CRP, iron and ferritin levels did not affect the HR for HF. RDW levels are inversely associated with physical activity (per category β=-0.37, 95%CI -0.053 to -0.021, p<0.0001), independent of iron metabolism. However, the association between HF and RDW levels was not changed by physical activity.

CONCLUSIONS

This study confirms that RDW is associated with HF events in an apparently healthy middle-aged population. More importantly, we show that the underlying pathophysiology linking HF with anisocytosis is not reflected by conventional risk factors, nor it is explained by iron metabolism or inflammation. Furthermore, RDW levels were associated with physical inactivity, but this did not influence the RDW-associated-risk of heart failure.

The reference intervals for the haematological parameters in healthy adult population of chennai, southern India

BACKGROUND

The haematological parameters are influenced by various factors like age, ethnicity, diet, genetic and gender differences and hence it is important to define the specific reference values with regards to the age, gender and the region. The indices like the Red Cell Distribution Width (RDW), the Mean Platelet Volume (MPV) and the Platelet Distribution Width (PDW) are newer haematological parameters which are calculated by automated haematology analyzers. There is an increasing evidence that these are clinically valuable bio markers. But not many studies have estimated the reference intervals for these parameters in our population.

AIM AND OBJECTIVE

Our primary objective was to identify the gender specific reference intervals for RDW, MPV, PDW and other haematological parameters for the healthy adult population of our region. We also aimed at comparing the study reference intervals with the existing reference ranges.

MATERIALS AND METHODS

A retrospective review of 2443 medical case sheets of the individuals who attended the preventive health check up program in a tertiary care hospital in the year 2011, was done. With 500 subjects who satisfied our study criteria, the haematological reference intervals were established.

RESULTS

Gender specific reference intervals were established for the newer indices as well as for the other haematological parameters. We derived the reference intervals for the newer parameters in our population as: RDW: 12.23%-15.36% in males and 12.3%-15.85% in females. MPV: 7.9 fL-13.7 fL in males and 8 fL -13.28 fL in females PDW: 9 fL -16.56 fL in males and 8 fL -13.28 fL in females.

CONCLUSION

Our values differed from the existing haematological reference values, thus showing the importance of developing region-specific reference intervals. Our data also showed the importance of establishing gender specific reference intervals.

Red blood cell distribution width and its relation to cardiac function and biomarkers in a prospective hospital cohort referred for echocardiography

BACKGROUND

Red blood cell distribution width (RDW), a measure of anisocytosis, is a prognostic biomarker for heart failure (HF). However it is still unclear how RDW is associated with heart function and established cardiac biomarkers.

METHODS AND RESULTS

In a prospective hospital cohort of 296 patients referred for echocardiography because of suspected HF, blood sampling and clinical examination were performed within 24h after echocardiography. The patients were divided into four HF groups, including one group where the HF diagnosis was uncertain (gray zone). In the patients the mean age was 70 ± 11 years, 44% with systolic HF (SHF), 18% with heart failure with normal ejection fraction (HFNEF), 17% with gray zone and 21% without HF (non-HF). RDW was higher among patients with SHF and HFNEF, compared with gray zone and non-HF patients. The distribution of different variables over the RDW quartiles showed an inverse correlation between RDW levels and LVEF and a positive correlation between RDW and NT-proBNP levels. Further analysis with stepwise multiple linear regression demonstrated that NT-proBNP levels, but not LVEF, were independently correlated with RDW.

CONCLUSION

In patients referred for echocardiography because of suspected HF, RDW levels were higher in patients with SHF and HFNEF. Moreover, NT-proBNP levels were independently linked with elevated RDW.

Red blood cell distribution width, multimorbidity, and the risk of death in hospitalized older patients

We aimed to assess the association between red blood cell distribution width (RDW) and mortality in patients enrolled by a Geriatric Department. One hundred twenty-two patients were followed up during 5 years. The primary end point was all-cause mortality, and hazard ratios were estimated using a Cox proportional hazard model. Higher RDW values were strongly associated with an increased risk of death. Survival curves across RDW quartiles were statistically different according to the log-rank test (p = 0.017). The first quartile presented higher probability of survival compared to the last one. The gradient from lower to higher risk across quartiles was clear both in the 5-year mortality risk and in the mortality rate per 100 person-years, which ranged from 18.9 to 42.6. However, in the Cox regression model after adjusting for age, severity, and other factors, excess risk was only observed in the highest RDW quartile, with a hazard ratio of 2.24 (CI(95%) 1.13-4.42) vs the first quartile. RDW is a good predictor of mortality in hospitalized older adults beyond those with cardiovascular risk factors, and it could serve as an integrative measure of multiple clinical and subclinical processes simultaneously occurring in complex patients.

Association between red cell distribution width and disease activity in patients with inflammatory bowel disease

BACKGROUND

Recent studies have suggested that a higher red blood cell distribution width (RDW) is associated with disease activity in patients with inflammatory bowel disease (IBD). However, the RDW in IBD patients without anemia has not been investigated.

AIM

This study aimed to determine whether or not RDW could be used for the assessment of disease activity in IBD patients with and without anemia.

METHODS

The serum C-reactive protein (CRP) level, erythrocyte sedimentation rate (ESR), hemoglobin concentration, platelet and white blood cell counts, and RDW were assessed in 221 IBD patients, comprised of 120 patients with ulcerative colitis (UC) and 101 patients with Crohn's disease (CD). Disease activity was determined for UC and CD with the Mayo score and the Crohn's disease activity index, respectively.

RESULTS

The CRP level, ESR, hemoglobin concentration, hematocrit, and RDW increased according to disease activity in patients with and without anemia (all P < 0.05). Multivariate analysis demonstrated that RDW was the best independent indicator for predicting disease activity in CD patients without anemia [odd ratios (OR), 1.702; 95% confidence interval (CI), 1.185-2.445; P = 0.004] and UC patients without anemia (OR, 4.921; 95% CI, 2.281-10.615; P < 0.001). Also, ROC curve analysis showed the RDW to be the most significant indicator of non-anemic active IBD [area under curve (AUC) in CD, 0.852, P < 0.001; AUC in UC, 0.827, P < 0.001].

CONCLUSION

The association between increased RDW and active IBD was evident in IBD patients with and without anemia.

Usefulness of red cell distribution width to predict mortality in patients with peripheral artery disease

Increased red blood cell distribution width (RDW), a marker of anisocytosis, has been associated with adverse outcomes in multiple settings. Whether RDW is predictive of mortality in patients with peripheral artery disease (PAD) is unknown. We studied 13,039 consecutive outpatients (69.5 ± 12.0 years of age, 60.9% men, 97.6% white) with PAD identified by noninvasive lower-extremity arterial testing at the Mayo Clinic from January 1997 through December 2007, with follow-up through September 2009. We defined PAD as a low (≤ 0.9) or high (≥ 1.4) ankle-brachial index (ABI). Cardiovascular risk factors and co-morbidities were ascertained using electronic medical record-based algorithms. RDW was obtained from the complete blood cell count drawn around the time of arterial evaluation. Mortality was ascertained using the Mayo electronic medical record and Accurint databases. Association of RDW with all-cause mortality was analyzed by multivariable Cox proportional hazards regression. During a median follow-up of 5.5 years, 4,039 (31.0%) deaths occurred (28.7% in low and 38.9% in high ABI subsets). After adjustment for age, gender, cardiovascular risk factors, and co-morbidities, patients in the highest quartile of RDW (> 14.5%) had a 66% greater risk of mortality compared to the lowest quartile (< 12.8%, p < 0.0001); a 1% increment in RDW was associated with a 10% greater risk of all-cause mortality (hazard ratio 1.10, 95% confidence interval 1.08 to 1.12, p < 0.0001). The adjusted hazard ratio was similar in the low (1.10, 1.08 to 1.12) and high (1.09, 1.06 to 1.12) ABI subsets. In conclusion, RDW, a routinely available measurement, is an independent prognostic marker in patients with PAD.