Abstract
Background: Cardiovascular disease (CVD) significantly increases in postmenopausal women. This study aims to investigate the potential association between red cell distribution width (RDW), the RDW-to-albumin ratio (RAR), and the prevalence of CVD in postmenopausal women.
Methods: This study analyzed data extracted from the National Health and Nutrition Examination Survey (NHANES) database spanning the years 2003-2016. Weighted multiple logistic regression models were used to evaluate the associations between RDW, RAR, and CVD. Smoothing curve fitting and generalized additive models were applied to explore potential nonlinear relationships. Subgroup analyses and interaction tests were conducted to investigate whether the associations between RDW, RAR, and CVD varied across different subpopulations. Sensitivity analyses were performed to assess the robustness of the findings.
Results: This study included a total of 7619 postmenopausal women, of whom 1181 had CVD. Logistic regression models revealed that for each unit increase in RDW and RAR, the risk of total CVD in postmenopausal women increased by 11% and 42%, respectively. When RDW and RAR were categorized into groups, the risk of CVD significantly increased with higher levels of RDW and RAR. Smoothing curve fitting demonstrated a nonlinear relationship between RDW, RAR, and total CVD. Subgroup analyses revealed that the positive associations between RDW, RAR, and CVD were particularly significant in individuals
aged ≥60 years and with a body mass index (BMI) ≥25 kg/m².
Conclusion: Higher RDW and RAR in postmenopausal women are positively associated with an increased risk of CVD, supporting the potential use of RDW and RAR as risk bio-markers for CVD in this population.
Highlights
- We found that higher RDW and RAR in postmenopausal women were positively associated with an increased risk of CVD.
- Red cell distribution width and RAR may serve as risk biomarkers for CVD in this population.
- Red cell distribution width and RAR are readily accessible biomarkers that can be utilized to predict the risk of CVD in postmenopausal women.
Introduction
Cardiovascular disease (CVD) is one of the leading causes of the global disease burden and a major contributor to mortality worldwide. According to the 2019 Global Burden of Disease study, the total number of CVD cases increased from 271 million in 1990 to 523 million in 2019, accompanied by a continuous rise in mortality.1 The 2011 American Heart Association guidelines for CVD prevention in women highlighted common and sex-specific risk factors, significantly enhancing awareness of gender differences in CVD.2 Menopause marks the decline or complete cessation of ovarian function, cessation of menstruation, and termination of natural reproductive capacity. Natural menopause is defined as the absence of menstruation for ≥12 consecutive months, signaling the end of a woman’s reproductive cycle. Menopause is a critical bio-psycho-social transition point linked to increased CVD risk.3,
The red cell distribution width (RDW), a parameter derived from routine complete blood count (CBC) tests, measures the variation in red blood cell (RBC) size and serves as an indicator of RBC size heterogeneity.9 Elevated RDW indicates greater variation in RBC volume in peripheral blood and is commonly used alongside other blood cell parameters to differentiate hematological diseases.10 Recently, RDW has been strongly and independently associated with various inflammatory markers,11,
To elucidate the clinical significance of RDW and RAR in postmenopausal women and identify valuable CVD risk biomarkers, the authors analyzed data from the NHANES 2003-2016 cycles to investigate the associations of RDW and RAR with CVD.
Methods
Data Source
The NHANES is conducted by the National Center for Health Statistics (NCHS), a division of the U.S. Centers for Disease Control and Prevention (CDC). It is designed to assess the health and nutritional status of adults and children in the United States through a combination of interviews, physical assessments, and laboratory analyses. The survey protocol is reviewed and approved by the NCHS Research Ethics Review Board, and all participants provide written informed consent prior to participation. Detailed information about the NHANES protocol and procedures has been described elsewhere.23
Study Population
We extracted data from 7 NHANES cycles (2003-2016), which included 71 058 participants in total.
The exclusion criteria were as follows: (1) male participants (n = 35 122); (2) premenopausal women or women with missing menopausal status information (n = 27 334); (3) participants with missing RDW or RAR data (n = 490); (4) participants with missing CVD questionnaire data (n = 106), including congestive heart failure (n = 28), coronary heart disease (n = 29), angina pectoris (n = 22), heart attack (n = 14), stroke (n = 13); (5) participants with missing data on necessary covariates (n = 387). Ultimately, 7619 postmenopausal women were included in the analysis. The screening process is illustrated in
Menopausal Status Definitions
Menopausal status was defined based on responses to reproductive health-related questions in the NHANES questionnaire. Women who answered “No” to the first question, “Have you had at least 1 menstrual period in the past 12 months? (Please do not include bleeding caused by medical conditions, hormone therapy, or surgeries),” and “Hysterectomy or menopause/lifestyle changes” to the second question, “What is the reason that you have not had a period in the past 12 months?” were considered postmenopausal.24,
Exposure Variables and Outcome Variables
Red cell distribution width (%) was obtained from the CBC section of the laboratory data, while serum albumin (g/dL) was sourced from the standard biochemical profile section.
Cardiovascular disease was derived from the questionnaire, based on self-reported diagnoses from a doctor or other healthcare professional of congestive heart failure, coronary heart disease, angina pectoris, heart attack, or stroke. A “Yes” answer to any of these 5 questions was used to define CVD.26
Covariates
This study, based on relevant literature,27,
Statistical Analysis
To reduce the variability in the dataset, the authors applied weighting adjustments according to the CDC guidelines.29 The statistical analyses incorporated sample weights, clustering, and stratification. Continuous variables are presented as means with 95% CI, while categorical variables are reported as percentages with 95% CI. Weighted linear regression or weighted chi-square tests were used to assess differences between participants with and without CVD. The primary outcome of this study was the presence of CVD, defined as a self-reported history of any of the following conditions: heart failure, coronary heart disease, angina, myocardial infarction, or stroke. Participants reporting at least one of these conditions were classified as having CVD (yes/no). In addition, each of the 5 CVD subtypes was analyzed separately as a binary outcome in subtype-specific analyses. The primary independent variables were RDW and RAR, which were first entered into weighted binary logistic regression models as continuous variables to evaluate their associations with overall CVD and its subtypes. To further assess the robustness of the findings, RDW and RAR were also categorized into quartiles and included in the models as categorical variables. Three multiple models were constructed with progressive adjustment for covariates: Model 1 (adjusted for age, race, education level and PIR); Model 2 (further adjusted for BMI, smoking, alcohol consumption, physical activity, family history of heart disease, history of female hormone use, and history of anemia treatment, in addition to the variables in Model 1); Model 3 (Additionally adjusted for hypertension, diabetes, self-reported cancer history, TC, HDL-C, and eGFR, building upon the adjustments in Model 2 (page 7, line 129-145)). Smoothed curve fitting and generalized additive models were used to assess potential nonlinear relationships between RDW, RAR, and CVD. Subgroup analyses and interaction tests were conducted to explore potential differences in the association of RDW and RAR with CVD across various populations of postmenopausal women. Finally, to test the robustness of the results, a sensitivity analysis was performed excluding participants with a history of cancer. All analyses were performed using the R software and EmpowerStats. Statistical significance was set at
Baseline Characteristics
This study included a total of 7619 postmenopausal women, of whom 1181 were diagnosed with CVD.
Association between Red Cell Distribution Width (RDW), Red Cell Distribution Width-to-Albumin Ratio, and Total Cardiovascular Disease
Across the 3 models, the association between RDW, RAR, and CVD gradually attenuated as more covariates were adjusted for, suggesting that some covariates may have a confounding effect on this relationship. Detailed parameter estimates, including OR, 95% CI, and
In the analysis of CVD subtypes (Supplementary Table 2), Model 3 revealed significant positive associations between higher RDW levels and the risks of congestive heart failure (
We then adjusted for the covariates in model 3 and used smoothing curve fitting to describe the nonlinear association between RDW, RAR, and total CVD in postmenopausal women (
Subgroup Analyses
To account for the influence of different population characteristics on total CVD risk, the authors performed subgroup analyses to determine whether the associations of RDW and RAR with CVD were consistent. As shown in
Sensitivity analysis
To verify the robustness of the authors’ results, they conducted a logistic regression model analysis excluding participants with cancer. The sensitivity analysis results indicated that the associations between RDW, RAR, and total CVD, as well as its subtypes, remained consistent with the above findings (Supplementary Table 3).
Discussion
This cross-sectional study found a significant positive association between RDW, RAR, and total CVD risk in postmenopausal women. Higher levels of RDW and RAR were also associated with an increased risk of congestive heart failure, coronary artery disease, myocardial infarction, and stroke. Subgroup analyses and interaction results indicated that the positive association between RDW, RAR, and CVD was consistent across different populations, suggesting that RDW and RAR could serve as biomarkers for assessing CVD risk in postmenopausal women.
Previous studies have reported associations between certain biomarkers and CVD risk in postmenopausal women. For example, serum transferrin levels have been linked to traditional cardiovascular risk factors.30 A prospective cohort study demonstrated a significant association between the triglyceride-glucose (TyG) index and total CVD in postmenopausal women.31 Another study, which included postmenopausal women without a history of CVD or cancer, showed that elevated homocysteine levels increased the risk of CVD after a 3-year follow-up, potentially due to hyperhomocysteinemia-induced endothelial dysfunction and dysregulation of circulating endothelial progenitor cells.32,
This study reveals a significant positive correlation between RDW and CVD events in postmenopausal women. After menopause, significant changes in hormone levels may disrupt the normal regulation of erythropoiesis. An increase in RDW indicates greater heterogeneity in red blood cell production, suggesting abnormal development of some red blood cells. This imbalance in erythropoiesis may affect the production and function of erythropoietin, leading to the formation of red blood cells of varying sizes, which in turn impairs the effective delivery of oxygen.37 To compensate for inadequate oxygen delivery, the heart must increase its pumping workload, which, over time, may lead to myocardial hypertrophy and impaired function, thereby increasing the risk of CVD.38 In addition, postmenopausal women are often in a state of chronic low-grade inflammation, with elevated levels of inflammatory markers such as tumor necrosis factor-α and interleukin-6.39 These inflammatory markers may not only disrupt the stability of red blood cell membranes, making them more prone to damage, but they can also directly injure the vascular endothelium, impairing the vessels’ anticoagulant, antithrombotic, and vascular tone-regulating functions, thereby promoting thrombosis and the development of atherosclerosis.40,
The physiological mechanisms underlying the association between RAR and cardiovascular events may involve the synergistic effects of nutritional metabolic imbalance, chronic inflammation, and oxidative stress. Serum albumin is a key indicator of nutritional status, and postmenopausal women often experience malnutrition due to physiological decline and changes in dietary habits.42 The combined effect of low albumin levels and elevated RDW, resulting in a higher RAR value, suggests that the body may be in a state of malnutrition and metabolic disturbance. Hypoalbuminemia leads to a decrease in plasma colloid osmotic pressure, causing tissue edema and increasing the heart’s preload.43 Nutritional deficiency may also affect myocardial energy metabolism and the integrity of cellular structures, further leading to a decline in cardiac function.44 An elevated RAR not only reflects a state of malnutrition but is also closely associated with chronic inflammation and oxidative stress. In a chronic inflammatory environment, the body’s antioxidant defense system becomes imbalanced, exacerbating oxidative stress. High levels of reactive oxygen species can oxidatively modify serum albumin, reducing its anti-inflammatory effects and further exacerbating damage to red blood cell membranes.45 Additionally, inflammation and oxidative stress activate a series of cellular signaling pathways that promote the proliferation and migration of vascular smooth muscle cells, accelerating the formation of atherosclerotic plaques and ultimately increasing the risk of cardiovascular disease.46
In conclusion, this study found a positive association between RDW, RAR levels, and CVD risk in postmenopausal women. For women with elevated RDW and RAR levels, early individualized interventions are recommended. These may include adopting a healthy diet, engaging in regular exercise, and consulting with a healthcare provider to determine whether hormone replacement therapy is appropriate.
Strengths and Limitations
This study has several strengths. It is the first extensive cross-sectional investigation to explore the association between RDW, RAR, and CVD in postmenopausal women. By considering the complex sampling design of NHANES, the study population has strong national representativeness. Additionally, the large sample size and adjustment for confounding variables contribute to the robustness and reliability of the findings. Lastly, sensitivity analyses further confirmed the consistency of the results. However, this study also has limitations. First, the cross-sectional design prevents the determination of causal relationships between RDW, RAR, and CVD. Second, the outcome variables were derived from self-reported questionnaires, which may introduce recall bias or misclassification in the diagnosis of CVD. Although self-reported data are commonly used in large-scale epidemiological studies like NHANES, they are inherently less accurate than clinically confirmed diagnoses. Nevertheless, the large sample size and population-based nature of the NHANES dataset help mitigate this limitation to some extent. Future studies should incorporate clinically verified diagnostic data to improve validity. Lastly, although extensive adjustments were made for potential confounders that could influence the association between RDW, RAR, and CVD, unmeasured factors may still affect the results. Future prospective cohort studies are needed to clarify the specific relationship between RDW, RAR, and CVD in postmenopausal women.
Conclusion
Red cell distribution width and RAR are readily accessible biomarkers that can be utilized to predict the risk of CVD in postmenopausal women. When RDW and RAR levels are abnormally elevated, postmenopausal women should be aware of the potential risk of CVD and take proactive measures for prevention. However, due to the limitations of this study, further prospective research is needed to explore the causal relationship between RDW, RAR, and CVD in postmenopausal women.
Supplementary Materials
Footnotes
References
- Cieza A, Causey K, Kamenov K, Hanson SW, Chatterji S, Vos T. Global estimates of the need for rehabilitation based on the Global Burden of Disease study 2019: a systematic analysis for the Global Burden of Disease Study 2019. Lancet. 2021;396(10267):2006-2017.
- Mosca L, Benjamin EJ, Berra K. Effectiveness-based guidelines for the prevention of cardiovascular disease in women--2011 update: a guideline from the American Heart Association. J Am Coll Cardiol. 2011;57(12):1404-1423.
- Nelson HD. Menopause. Lancet (London, England). 2008;371(9614):760-770.
- Wellons M, Ouyang P, Schreiner PJ, Herrington DM, Vaidya D. Early menopause predicts future coronary heart disease and stroke: the Multi-Ethnic Study of Atherosclerosis. Menopause (New York, NY). 2012;19(10):1081-1087.
- Anand SS, Islam S, Rosengren A. Risk factors for myocardial infarction in women and men: insights from the INTERHEART study. Eur Heart J. 2008;29(7):932-940.
- Mendelsohn ME, Karas RH. Molecular and cellular basis of cardiovascular gender differences. Science (New York, NY). 2005;308(5728):1583-1587.
- Rosano GM, Vitale C, Marazzi G, Volterrani M. Menopause and cardiovascular disease: the evidence. Climacteric. 2007;10(Suppl):19-24.
- Virani SS, Alonso A, Benjamin EJ. Heart disease and stroke Statistics-2020 update: a report from the American Heart Association. Circulation. 2020;141(9):e139-e596.
- Salvagno GL, Sanchis-Gomar F, Picanza A, Lippi G. Red blood cell distribution width: a simple parameter with multiple clinical applications. Crit Rev Clin Lab Sci. 2015;52(2):86-105.
- Seo IH, Lee YJ. Usefulness of complete blood count (CBC) to assess cardiovascular and metabolic diseases in clinical settings: a comprehensive literature review. Biomedicines. 2022;10(11):2697-.
- He Y, Liu C, Zeng Z, Ye W, Lin J, Ou Q. Red blood cell distribution width: a potential laboratory parameter for monitoring inflammation in rheumatoid arthritis. Clin Rheumatol. 2018;37(1):161-167.
- Horta-Baas G, Romero-Figueroa MDS. Clinical utility of red blood cell distribution width in inflammatory and non-inflammatory joint diseases. Int J Rheum Dis. 2019;22(1):47-54.
- Tonelli M, Sacks F, Arnold M. Relation between red blood cell distribution width and cardiovascular event rate in people with coronary disease. Circulation. 2008;117(2):163-168.
- Gao C, Peng L. Association and prediction of red blood cell distribution width to albumin ratio in all-cause mortality of acute kidney injury in critically ill patients. Front Med (Lausanne). 2023;10():1047933-.
- Artigas A, Wernerman J, Arroyo V, Vincent JL, Levy M. Role of albumin in diseases associated with severe systemic inflammation: pathophysiologic and clinical evidence in sepsis and in decompensated cirrhosis. J Crit Care. 2016;33():62-70.
- Jiang Y, Yang Z, Wu Q, Cao J, Qiu T. The association between albumin and C-reactive protein in older adults. Medicine. 2023;102(34):e34726-.
- Gopal DM, Kalogeropoulos AP, Georgiopoulou VV. Serum albumin concentration and heart failure risk The Health, Aging, and Body Composition Study. Am Heart J. 2010;160(2):279-285.
- Schalk BW, Visser M, Bremmer MA, Penninx BW, Bouter LM, Deeg DJ. Change of serum albumin and risk of cardiovascular disease and all-cause mortality: longitudinal Aging Study Amsterdam. Am J Epidemiol. 2006;164(10):969-977.
- Ni Q, Wang X, Wang J, Chen P. The red blood cell distribution width-albumin ratio: a promising predictor of mortality in heart failure patients - A cohort study. Clin Chim Acta Int J Clin Chem. 2022;527():38-46.
- Liu J, Wang X, Gao TY. Red blood cell distribution width to albumin ratio associates with prevalence and long-term diabetes mellitus prognosis: an overview of NHANES 1999-2020 data. Front Endocrinol. 2024;15():1362077-.
- Guo H, Wang Y, Miao Y, Lin Q. Red cell distribution width/albumin ratio as a marker for metabolic syndrome: findings from a cross-sectional study. BMC Endocr Disord. 2024;24(1):227-.
- Kimura H, Tanaka K, Saito H. Impact of red blood cell distribution width-albumin ratio on prognosis of patients with CKD. Sci Rep. 2023;13(1):15774-.
- Wong T, Dang K, Ladhani S, Singal AK, Wong RJ. Prevalence of alcoholic fatty liver disease among adults in the United States, 2001-2016. JAMA. 2019;321(17):1723-1725.
- Wang B, Xu W, Mei Z, Yang W, Meng X, An G. Association between serum klotho levels and estimated pulse wave velocity in postmenopausal women: a cross-sectional study of NHANES 2007-2016. Front Endocrinol. 2024;15():1471548-.
- Li J, Huang J, Lv Y, Ji H. Association between dietary intakes of B vitamins and nonalcoholic fatty liver disease in postmenopausal women: a cross-sectional study. Front Nutr. 2023;10():1272321-.
- Chen Y, Lin W, Fu L. Muscle quality index and cardiovascular disease among US population-findings from NHANES 2011-2014. BMC Public Health. 2023;23(1):2388-.
- Liu C, Lai W, Zhao M, Zhang Y, Hu Y. Association between the composite dietary antioxidant index and atherosclerotic cardiovascular disease in postmenopausal women: a cross-sectional study of NHANES data, 2013-2018. Antioxidants (Basel, Switzerland). 2023;12(9):1740-.
- Ainiwaer A, Kadier K, Abulizi A. Association of red cell distribution width (RDW) and the RDW to platelet count ratio with cardiovascular disease among US adults: a cross-sectional study based on the National Health and Nutrition Examination survey 1999-2020. BMJ Open. 2023;13(3):e068148-.
- . NHANES tutorials. National Health and Nutrition Examination Survey, Centers for Disease Control and Prevention 2021. ;():-. https://wwwn.cdc.gov/nchs/nhanes/tutorials/default.aspx
- Ahanchi NS, Fischer AS, Quezada-Pinedo HG. Cross-sectional and longitudinal associations of Iron biomarkers and cardiovascular risk factors in pre- and postmenopausal women: leveraging repeated measurements to address natural variability. Cardiovasc Diabetol. 2024;23(1):158-.
- Liu Q, Si F, Liu Z, Wu Y, Yu J. Association between triglyceride-glucose index and risk of cardiovascular disease among postmenopausal women. Cardiovasc Diabetol. 2023;22(1):21-.
- Ageenko AI, Kogan I. Proliferation of a culture of rat fibroblasts chronically infected with oncogenic A-12 virus. Vopr Onkol. 1976;22(9):78-80.
- Peng L, Gu Q, Huang Z, Zeng L, Chu C, Yang X. Rejuvenated circulating endothelial progenitor cells and nitric oxide in premenopausal women with hyperhomocysteinemia. Cardiol Res Pract. 2020;2020():5010243-.
- Liu L, Peng J, Zang D. The Chinese visceral adiposity index: a novel indicator more closely related to cardiovascular disease than other abdominal obesity indices among postmenopausal women. J Transl Med. 2024;22(1):855-.
- Zuercher MD, Harvey DJ, Santiago-Torres M. Dietary inflammatory index and cardiovascular disease risk in Hispanic women from the Women’s Health Initiative. Nutr J. 2023;22(1):5-.
- Zheng J, Tabung FK, Zhang J. Association between dietary inflammatory potential and mortality after cancer diagnosis in the Women’s Health Initiative. Br J Cancer. 2023;128(4):606-617.
- Westenbrink BD, Voors AA, Ruifrok WPT, van Gilst WH, van Veldhuisen DJ. Therapeutic potential of erythropoietin in cardiovascular disease: erythropoiesis and beyond. Curr Heart Fail Rep. 2007;4(3):127-133.
- Sato T, Takeda N. The roles of HIF-1α signaling in cardiovascular diseases. J Cardiol. 2023;81(2):202-208.
- Sinatora RV, Chagas EFB, Mattera FOP. Relationship of inflammatory markers and metabolic syndrome in postmenopausal women. Metabolites. 2022;12(1):73-.
- Levi M, van der Poll T, Büller HR. Bidirectional relation between inflammation and coagulation. Circulation. 2004;109(22):2698-2704.
- Cheng C, Tempel D, Den Dekker WK. Ets2 determines the inflammatory state of endothelial cells in advanced atherosclerotic lesions. Circ Res. 2011;109(4):382-395.
- Vázquez-Lorente H, Herrera-Quintana L, Molina-López J, López-González B, Planells E. Sociodemographic, anthropometric, body composition, nutritional, and biochemical factors influenced by age in a postmenopausal population: a cross-sectional study. Metabolites. 2023;13(1):78-.
- Arques S. Human serum albumin in cardiovascular diseases. Eur J Intern Med. 2018;52():8-12.
- Manolis AA, Manolis TA, Melita H, Mikhailidis DP, Manolis AS. Low serum albumin: a neglected predictor in patients with cardiovascular disease. Eur J Intern Med. 2022;102():24-39.
- Mazzulla S, Schella A, Gabriele D. Oxidation of human red blood cells by a free radical initiator: effects on rheological properties. Clin Hemorheol Microcirc. 2015;60(4):375-388.
- Plantier JL, Duretz V, Devos V, Urbain R, Jorieux S. Comparison of antioxidant properties of different therapeutic albumin preparations. Biologicals. 2016;44(4):226-233.