Health Behaviors in Younger and Older Adults With CKD: Results From the CRIC Study

[Characteristics and needs of patients requiring nephrology care: A review of the literature]

Chronic kidney disease (CKD) is a public health problem. However, the management of patients with CKD is confined to the diagnosis of the disease and its conventional treatment by dialysis or renal transplantation. The aim of this article is to describe the specific characteristics of patients suffering from kidney disease and to determine their needs according to the stage of their renal disease.

Preferences of people with chronic kidney disease regarding digital health interventions that promote healthy lifestyle: qualitative systematic review with meta-ethnography

OBJECTIVES

Diet and physical activity are crucial for people with chronic kidney disease (CKD) to maintain good health. Digital health interventions can increase access to lifestyle services. However, consumers' perspectives are unclear, which may reduce the capacity to develop interventions that align with specific needs and preferences. Therefore, this review aims to synthesise the preferences of people with CKD regarding digital health interventions that promote healthy lifestyle.

DESIGN

Qualitative systematic review with meta-ethnography.

DATA SOURCES

Databases Scopus, CENTRAL, MEDLINE, CINAHL and SPORTDiscus were searched between 2000 and 2023.

ELIGIBILITY CRITERIA

Primary research papers that used qualitative exploration methods to explore the preferences of adults with CKD (≥18 years) regarding digital health interventions that promoted diet, physical activity or a combination of these health behaviours.

DATA EXTRACTION AND SYNTHESIS

Two independent reviewers screened title, abstract and full text. Discrepancies were resolved by a third reviewer. Consumers' quotes were extracted verbatim and synthesised into higher-order themes and subthemes.

RESULTS

Database search yielded 5761 records. One record was identified following communication with a primary author. 15 papers were included. These papers comprised 197 consumers (mean age 51.0±7.2), including 83 people with CKD 1-5; 61 kidney transplant recipients; 53 people on dialysis. Sex was reported in 182 people, including 53% male. Five themes were generated regarding consumers' preferences for digital lifestyle interventions. These included simple instruction and engaging design; individualised interventions; virtual communities of care; education and action plans; and timely reminders and automated behavioural monitoring.

CONCLUSION

Digital health interventions were considered an important mechanism to access lifestyle services. Consumers' preferences are important to ensure future interventions are tailored to specific needs and goals. Future research may consider applying the conceptual framework of consumers' preferences in this review to develop and evaluate the effect of a digital lifestyle intervention on health outcomes.

PROSPERO REGISTRATION NUMBER

CRD42023411511.

Psychological Distress and Self-Management in CKD: A Cross-Sectional Study

Rationale & Objective

Patients with chronic kidney disease (CKD) not receiving dialysis, including kidney transplant recipients, often experience difficulties regarding self-management. An important barrier for adherence to self-management recommendations may be the presence of psychological distress, consisting of depressive and anxiety symptoms. We investigated relationships between psychological distress and adherence to self-management recommendations.

Study Design

Cross-sectional online questionnaire data as part of the E-GOAL study.

Setting & Participants

Patients with CKD (estimated glomerular filtration rate, 20-89 mL/min/1.73 m2) were recruited from April 2018 to October 2020 at 4 hospitals in The Netherlands and completed online screening questionnaires.

Exposures

Psychological distress, depressive symptoms, and anxiety symptoms.

Outcomes

Dietary adherence, physical activity, medication adherence, smoking, body mass index, and a CKD self-management index (ie, the sum of 5 binary indicators of nonadherence to the recommended self-management factors).

Analytical Approach

Adjusted multivariable regression and ordinal logistic regression analyses.

Results

In our sample (N = 460), 27.2% of patients reported psychological distress, and 69.8% were nonadherent to 1 or more recommendations. Higher psychological distress was significantly associated with poorer dietary adherence (βadj, -0.13; 95% CI, -0.23 to -0.04), less physical activity (βadj, -0.13; 95% CI, -0.22 to -0.03), and lower medication adherence (βadj, -0.15; 95% CI, -0.24 to -0.05), but not with smoking and body mass index. Findings were similar for depressive symptoms, whereas anxiety was only associated with poorer dietary and medication adherence. Every 1-point higher psychological distress was also associated with a higher likelihood of being nonadherent to an accumulating number of different recommendations (adjusted OR, 1.04; 95% CI, 1.02-1.07).

Limitations

Cross-sectional design, possible residual confounding, and self-report.

Conclusions

Many people with CKD experience psychological distress, of whom most have difficulties self-managing their CKD. Given the relationship between psychological distress and adherence to CKD self-management recommendations, behavioral interventions are needed to identify and treat psychological distress as a potential barrier to CKD self-management.

Plain-Language Summary

This online questionnaire study investigated relationships between psychological distress and self-management among 460 people with chronic kidney disease. Over a quarter of them reported mild-to-severe psychological distress. Alarmingly, 4 out of 5 patients with psychological distress were also nonadherent to 1 or more self-management recommendations, and higher levels of psychological distress were associated with poorer dietary and medication adherence and lower physical activity. Moreover, patients who suffered from moderate-to-severe distress were relatively more often nonadherent to 3 or more recommendations compared with patients with no or mild distress symptoms. So, it seems that psychological distress can be a barrier for self-management. To support patients in managing chronic kidney disease, researchers and health professionals should not overlook patients' mental health.

Predialysis trajectories of estimated GFR and concurrent trends of Chronic Kidney Disease-relevant biomarkers

Background

The glomerular filtration rate (GFR) decline varies in patients with advanced chronic kidney disease (CKD), and the concurrent changes in CKD-related biomarkers are unclear.

Objectives

This study aimed to examine the changes in CKD-related biomarkers along with the kidney function decline in various GFR trajectory groups.

Design

This study was a longitudinal cohort study originated from the pre-end-stage renal disease (pre-ESRD) care program in a single tertiary center between 2006 and 2019.

Methods

We adopted a group-based trajectory model to categorize CKD patients into three trajectories according to estimated glomerular filtration rate (eGFR) changes. A repeated-measures linear mixed model was used to estimate the concurrent biomarker trends in a 2-year period before dialysis and to examine the differences among trajectory groups. A total of 15 biomarkers were analyzed, including urine protein, serum uric acid, albumin, lipid, electrolytes, and hematologic markers.

Results

Using longitudinal data from 2 years before dialysis initiation, 1758 CKD patients were included. We identified three distinct eGFR trajectories: persistently low eGFR levels, progressive loss of eGFR, and accelerated loss of eGFR. Eight of the 15 biomarkers showed distinct patterns among the trajectory groups. Compared with the group with persistently low eGFR values, the other two groups were associated with a more rapid increase in the blood urea nitrogen (BUN) level and urine protein-creatinine ratio (UPCR), especially in the year before dialysis initiation, and a more rapid decline in hemoglobin and platelet counts. A rapid eGFR decline was associated with lower levels of albumin and potassium, and higher levels of mean corpuscular hemoglobin concentration (MCHC) and white blood cell (WBC). The albumin level in the group with an accelerated loss of eGFR was below the normal range.

Conclusion

Using longitudinal data, we delineated the changes in CKD biomarkers with disease progression. The results provide information to clinicians and clues to elucidate the mechanism of CKD progression.

The potential of mHealth for older adults on dialysis and their care partners: What's been done and where do we go from here?

Self-care, or the dynamic, daily process of becoming actively involved in one's own care, is paramount to prevent and manage complications of end-stage kidney disease. However, many older dialysis patients face distinctive challenges to adequate engagement in self-care. One promising strategy for facilitating self-care among older dialysis patients and their care partners is the utilization of mobile health (mhealth). mHealth encompasses mobile and wireless communication devices used to improve healthcare delivery, patient and care partner outcomes, and patient care. In other disease populations, mHealth has been linked to maintenance of or improvements in self-management, medication compliance, patient education, and patient-provider communication, all of which can slow disease progression. Although mHealth is considered feasible, acceptable, and clinically useful, this technology has predominately targeted younger patients. Thus, there is a need to develop mHealth for older dialysis patients and their care partners. In this article, we describe current mHealth usage in older dialysis patients, including promising findings, challenges, and research gaps. Given the lack of research on mHealth among care partners of older dialysis patients, we highlight lessons learned from other disease populations to inform the future design and implementation of mHealth for these key stakeholders. We also propose that leveraging care partners represents an opportunity to meaningfully tailor mHealth applications and, by extension, improve care partner physical and mental health and decrease caregiver burden. We conclude with a summary of future directions to help older dialysis patients and their care partners receive recognition as target end-users amid the constant evolution of mHealth.

Effect of Uncertainty in Illness and Fatigue on Health-Related Quality of Life of Patients on Dialysis: A Cross-Sectional Correlation Study

This study aimed to determine the effect of uncertainty in illness and fatigue on the health-related quality of life of patients on dialysis. A community-based cross-sectional study was conducted among patients on hemodialysis (n = 80) and peritoneal dialysis (n = 81) in Korea. Data were collated using self-reported structured questionnaires. Multiple regression analysis was used to identify those factors affecting the physical and mental health-related quality of life of patients. Patients on peritoneal dialysis reported higher levels of fatigue (p < 0.001). Factors affecting the physical health-related quality of life of patients on dialysis were fatigue (p < 0.001), employment (p = 0.001), and exercise (p = 0.016), thus explaining the observed variance of 37%. Factors affecting mental health-related quality of life were fatigue (p < 0.001), uncertainty (p = 0.004), educational level (p = 0.005), and smoking (p = 0.035). To improve the health-related quality of life of patients on dialysis, clinicians should assess their fatigue levels and plan multidisciplinary interventions to manage it. In addition, education level and employment status should be considered, and tailored interventions should be provided to acquire positive coping strategies and health promotion behaviors to counter disease uncertainty.

Associations of Anxiety during the COVID-19 Pandemic with Patient Characteristics and Behaviors in CKD Patients: Findings from the Chronic Renal Insufficiency Cohort (CRIC) Study

Background

Chronic kidney disease (CKD) is associated with anxiety and depression. Although the coronavirus disease 2019 (COVID-19) pandemic has increased stressors on patients with CKD, assessments of anxiety and its predictors and consequences on behaviors, specifically virus mitigation behaviors, are lacking.

Methods

From June to October 2020, we administered a survey to 1873 patients in the Chronic Renal Insufficiency Cohort (CRIC) Study, asking participants about anxiety related to the COVID-19 pandemic. We examined associations between anxiety and participant demographics, clinical indexes, and health literacy and whether anxiety was associated with health-related behaviors and COVID-19 mitigation behaviors.

Results

The mean age of the study population was 70 years (SD=9.6 years), 47% were women, 39% were Black non-Hispanic, 14% were Hispanic, and 38% had a history of cardiovascular disease. In adjusted analyses, younger age, being a woman, Hispanic ethnicity, cardiovascular disease, household income <$20,000, and marginal or inadequate health literacy predicted higher anxiety. Higher global COVID-19-related anxiety scores were associated with higher odds of reporting always wearing a mask in public (OR=1.3 [95% CI, 1.14 to 1.48], P<0.001) and of eating less healthy foods (OR=1.29 [95% CI, 1.13 to 1.46], P<0.001), reduced physical activity (OR=1.32 [95% CI, 1.2 to 1.45], P<0.001), and weight gain (OR=1.23 [95% CI, 1.11 to 1.38], P=0.001).

Conclusions

Higher anxiety levels related to the COVID-19 pandemic were associated not only with higher self-reported adherence to mask wearing but also with higher weight gain and less adherence to healthy lifestyle behaviors. Interventions are needed to support continuation of healthy lifestyle behaviors in patients with CKD experiencing increased anxiety related to the pandemic.

A longitudinal qualitative study to explore and optimize self-management in mild to end stage chronic kidney disease patients with limited health literacy: Perspectives of patients and health care professionals

OBJECTIVES

Limited health literacy (LHL) is associated with faster kidney deterioration. Health care professionals (HCPs) promote self-management to maintain kidney function, which is difficult for patients with LHL. Evidence lacks on perceived barriers and best strategies to optimize their self-management. Our study aims to explore experiences with and barriers for self-management from the perspectives of LHL patients and HCPs to identify strategies to optimize self-management.

METHODS

We performed a longitudinal qualitative study with semi-structured in-depth interviews and focus group discussions among CKD patients and LHL (n = 24) and HCPs (n = 37) from general practices and hospitals.

RESULTS

Four themes arose among patients: (1) CKD elusiveness, (2) suboptimal intake of knowledge (3) not taking a front-seat role, and (4) maintaining change. Among HCPs, three themes emerged: (1) not recognizing HL problems, (2) lacking effective strategies, and (3) health care barriers.

CONCLUSION

We suggest three routes to optimize self-management: providing earlier information, applying person-centered strategies to maintain changes, and improving competencies of HCPs.

PRACTICE IMPLICATIONS

HCPs need to explain CKD self-management better to prevent kidney deterioration. New interventions, based on behavioral approaches, are needed to optimize self-management. HCPs need training to improve recognition and support of LHL patients.

Cholesterol Metabolism in Chronic Kidney Disease: Physiology, Pathologic Mechanisms, and Treatment

High plasma levels of lipids and/or lipoproteins are risk factors for atherosclerosis, nonalcoholic fatty liver disease (NAFLD), obesity, and diabetes. These four conditions have also been identified as risk factors leading to the development of chronic kidney disease (CKD). Although many pathways that generate high plasma levels of these factors have been identified, most clinical and physiologic dysfunction results from aberrant assembly and secretion of lipoproteins. The results of several published studies suggest that elevated levels of low-density lipoprotein (LDL)-cholesterol are a risk factor for atherosclerosis, myocardial infarction, coronary artery calcification associated with type 2 diabetes, and NAFLD. Cholesterol metabolism has also been identified as an important pathway contributing to the development of CKD; clinical treatments designed to alter various steps of the cholesterol synthesis and metabolism pathway are currently under study. Cholesterol synthesis and catabolism contribute to a multistep process with pathways that are regulated at the cellular level in renal tissue. Cholesterol metabolism may also be regulated by the balance between the influx and efflux of cholesterol molecules that are capable of crossing the membrane of renal proximal tubular epithelial cells and podocytes. Cellular accumulation of cholesterol can result in lipotoxicity and ultimately kidney dysfunction and failure. Thus, further research focused on cholesterol metabolism pathways will be necessary to improve our understanding of the impact of cholesterol restriction, which is currently a primary intervention recommended for patients with dyslipidemia.

Food Literacy and Its Associated Factors in Non-Dialysis Patients with Chronic Kidney Disease in China: A Cross-Sectional Study

PURPOSE

Nephrology professionals' understanding of food literacy (FL) and influencing factors is significant for nutrition management, which is key to controlling disease progress among non-dialysis patients with chronic kidney disease (CKD). However, few studies have explored FL in CKD patients. Hence, this study aimed to investigate the level of FL of non-dialysis patients with CKD and to analyze influencing factors in China.

PATIENTS AND METHODS

A total of 203 CKD patients without dialysis were recruited from August to December 2020 to participate in a cross-sectional study. Food literacy was assessed by a modified short food literacy questionnaire for adults. Related influencing factors were measured by the motivation for dietary self-control scale and the satisfaction with dietary behavior scale. Data were also collected regarding patients' health information-seeking behavior (four items), satisfaction and compliance with dietary advice from healthcare professionals (two items), and demographics and clinical diagnoses.

RESULTS

The mean age of patients was 44.5 years (range 18 to 75), and 42.5% were male. Most (50.2%) were in stages 1-2 of CKD. The mean FL score of these patients was 38.75±0.38. The multivariable linear regression analysis shows that secondary educational level (β=0.221, p=0.004), motivation for controlling diet (β=0.198, p=0.003), satisfaction with dietary behaviors (β=0.319, p<0.001), and health information-seeking behavior (β=0.146, p=0.019) were significant influencing factors.

CONCLUSION

Food literacy of Chinese CKD patients without dialysis should be improved. Patients with higher education levels exhibit more active information-seeking behaviors, have greater satisfaction with dietary behaviors, and their motivation for dietary self-control is more likely to be associated with better FL. Healthcare workers should be aware of factors influencing FL and attempt to integrate assessment of FL into routine food-related education for CKD patients.

Co-Creation of a Multi-Component Health Literacy Intervention Targeting Both Patients with Mild to Severe Chronic Kidney Disease and Health Care Professionals

Limited health literacy (LHL) is common in chronic kidney disease (CKD) patients and frequently associated with worse self-management. Multi-component interventions targeted at patients and healthcare professionals (HCPs) are recommended, but evidence is limited. Therefore, this study aims to determine the objectives and strategies of such an intervention, and to develop, produce and evaluate it. For this purpose, we included CKD patients with LHL (n = 19), HCPs (n = 15), educators (n = 3) and students (n = 4) from general practices, nephrology clinics and universities in an Intervention Mapping (IM) process. The determined intervention objectives especially address the patients’ competences in maintaining self-management in the long term, and communication competences of patients and HCPs. Patients preferred visual strategies and strategies supporting discussion of needs and barriers during consultations to written and digital strategies. Moreover, they preferred an individual approach to group meetings. We produced a four-component intervention, consisting of a visually attractive website and topic-based brochures, consultation cards for patients, and training on LHL for HCPs. Evaluation revealed that the intervention was useful, comprehensible and fitting for patients’ needs. Healthcare organizations need to use visual strategies more in patient education, be careful with digitalization and group meetings, and train HCPs to improve care for patients with LHL. Large-scale research on the effectiveness of similar HL interventions is needed.

Consequences of Both Coxsackievirus B4 and Type 1 Diabetes on Female Non-Obese Diabetic Mouse Kidneys

Despite the 2019 Executive Order on Advancing American Kidney Health Initiative, kidney disease has moved up in rank from the 9th to the 8th leading cause of death in the United States. A recent push in the field of nephrology has been to identify molecular markers and/or molecular profiles involved in kidney disease process or injury that can help identify the cause of injury and predict patient outcomes. While these studies have had moderate success, they have not yet considered that many of the health conditions that cause kidney disease (diabetes, hypertension, etc.) can also be caused by environmental factors (such as viruses), which in and of themselves can cause kidney disease. Thus, the goal of this study was to identify molecular and phenotypic profiles that can differentiate kidney injury caused by diabetes (a health condition resulting in kidney disease) and coxsackievirus B4 (CVB4) exposure (which can cause diabetes and/or kidney disease), both alone and together. Non-obese diabetic (NOD) mice were used for this study due to their susceptibility to both type 1 diabetes (T1D)- and CVB4-mediated kidney injury, in order to glean a better understanding of how hyperglycemia and viral exposure, when occurring on their own and in combination, may alter the kidneys’ molecular and phenotypic profiles. While no changes in kidney function were observed, molecular biomarkers of kidney injury were significantly up- and downregulated based on T1D and CVB4 exposure, both alone and together, but not in a predictable pattern. By combining individual biomarkers with function and phenotypic measurements (i.e., urinary albumin creatinine ratio, serum creatinine, kidney weight, and body weight), we were able to perform an unbiased separation of injury group based on the type of injury. This study provides evidence that unique kidney injury profiles within a kidney disease health condition are identifiable, and will help us to identify the causes of kidney injury in the future.

Risk Factors for CKD Progression: Overview of Findings from the CRIC Study

The Chronic Renal Insufficiency Cohort (CRIC) Study is an ongoing, multicenter, longitudinal study of nearly 5500 adults with CKD in the United States. Over the past 10 years, the CRIC Study has made significant contributions to the understanding of factors associated with CKD progression. This review summarizes findings from longitudinal studies evaluating risk factors associated with CKD progression in the CRIC Study, grouped into the following six thematic categories: (1) sociodemographic and economic (sex, race/ethnicity, and nephrology care); (2) behavioral (healthy lifestyle, diet, and sleep); (3) genetic (apoL1, genome-wide association study, and renin-angiotensin-aldosterone system pathway genes); (4) cardiovascular (atrial fibrillation, hypertension, and vascular stiffness); (5) metabolic (fibroblast growth factor 23 and urinary oxalate); and (6) novel factors (AKI and biomarkers of kidney injury). Additionally, we highlight areas where future research is needed, and opportunities for interdisciplinary collaboration.

Food Literacy Is Associated With Adherence to a Mediterranean-Style Diet in Kidney Transplant Recipients

OBJECTIVES

Adherence to a Mediterranean-style diet is associated with improved health outcomes in kidney transplant recipients (KTR). However, poor dietary habits, including excessive sodium intake, are common in KTR, indicating difficulties with incorporating a healthy diet into daily life. Food literacy is identified as potential facilitator of a healthy diet, but the precise relationship between food literacy and dietary intake in KTR has not been investigated. This study examined food literacy levels in KTR and its association with adherence to a Mediterranean-style diet and sodium intake.

METHODS

This cross-sectional study is part of the TransplantLines Cohort and Biobank Study. Food literacy was measured with the Self-Perceived Food Literacy (SPFL) questionnaire. Dietary intake assessment with food frequency questionnaires was used to calculate the Mediterranean Diet Score. Sodium intake was based on the 24-hour urinary sodium excretion rate. Associations of SPFL with Mediterranean Diet Score and sodium intake were assessed with univariable and multivariable linear regression analyses.

RESULTS

In total, 148 KTR (age 56 [48-66]; 56% male) completed the SPFL questionnaire with a mean SPFL score of 3.63 ± 0.44. Higher SPFL was associated with a higher Mediterranean Diet Score in KTR (β = 1.51, 95% confidence interval 0.88-2.12, P ≤ .001). Although KTR with higher food literacy tended to have a lower sodium intake than those with lower food literacy (P = .08), the association of food literacy with sodium intake was not significant in a multivariable regression analysis (β = 0.52 per 10 mmol/24-hour increment, 95% confidence interval -1.79 to 2.83, P = .66).

CONCLUSIONS

Higher levels of food literacy are associated with better adherence to a Mediterranean-style diet in KTR. No association between food literacy and sodium intake was found. Further studies are needed to determine if interventions on improving food literacy contribute to a healthier diet and better long-term outcomes in KTR.

How to tackle health literacy problems in chronic kidney disease patients? A systematic review to identify promising intervention targets and strategies

BACKGROUND

Limited health literacy (LHL) is associated with multiple adverse health outcomes in chronic kidney disease (CKD). Interventions are needed to improve this situation, but evidence on intervention targets and strategies is lacking. This systematic review aims to identify potential targets and strategies by summarizing the evidence on: (i) patient- and system-level factors potentially mediating the relation between LHL and health outcomes; and (ii) the effectiveness of health literacy interventions customized to CKD patients.

METHODS

We performed a systematic review of peer-reviewed research articles in Medline, Embase and Web of Science, 2009-19. We assessed the quality of the studies and conducted a best-evidence synthesis.

RESULTS

We identified 860 publications and included 48 studies. Most studies were of low quality (n = 26) and focused on dialysis and transplantation (n = 38). We found strong evidence for an association of LHL with smoking and having a suboptimal transplantation process. Evidence was weak for associations between LHL and a variety of factors related to self-care management (n = 25), utilization of care (n = 23), patient-provider interaction (n = 8) and social context (n = 5). Six interventions were aimed at improving knowledge, decision-making and health behaviours, but evidence for their effectiveness was weak.

CONCLUSIONS

Study heterogeneity, low quality and focus on kidney failure largely impede the identification of intervention targets and strategies for LHL. More and higher quality studies in earlier CKD stages are needed to unravel how LHL leads to worse health outcomes, and to identify targets and strategies to prevent disease deterioration. Healthcare organizations need to develop and evaluate efforts to support LHL patients.

Everyday Discrimination and Kidney Function Among Older Adults: Evidence From the Health and Retirement Study

BACKGROUND

With advancing age, there is an increase in the time of and number of experiences with psychosocial stressors that may lead to the initiation and/or progression of chronic kidney disease (CKD). Our study tests whether one type of experience, everyday discrimination, predicts kidney function among middle and older adults.

METHODS

The data were from 10 973 respondents (ages 52-100) in the 2006/2008 Health and Retirement Study, an ongoing biennial nationally representative survey of older adults in the United States. Estimated glomerular filtration rate (eGFR) derives from the Chronic Kidney Disease Epidemiology Collaboration equation. Our indicator of everyday discrimination is drawn from self-reports from respondents. Ordinary Least Squared regression (OLS) models with robust standard errors are applied to test hypotheses regarding the link between everyday discrimination and kidney function.

RESULTS

Everyday discrimination was associated with poorer kidney function among respondents in our study. Respondents with higher everyday discrimination scores had lower eGFR after adjusting for demographic characteristics (B = -1.35, p < .05), and while attenuated, remained significant (B = -0.79, p < .05) after further adjustments for clinical, health behavior, and socioeconomic covariates.

CONCLUSIONS

Our study suggests everyday discrimination is independently associated with lower eGFR. These findings highlight the importance of psychosocial factors in predicting insufficiency in kidney function among middle-aged and older adults.

Overweight-obesity is associated with decreased vitamin K2 levels in hemodialysis patients

OBJECTIVES

Obesity is an important risk factor for morbidity and mortality. Vitamin K2 is involved in the production of bone and matrix amino acid g-carboxy-glutamic acid (Gla) proteins (vitamin K-dependent proteins [VKDPs]), regulating bone and vascular calcification (VC). Bone Gla protein (BGP) is involved both in bone mineralization and VCs. We assessed the relationships between vitamin K levels and body mass index (BMI) according to the hypothesis that the impact of BMI on mortality is partly driven by low vitamin K levels.

METHODS

The Vitamin K Italian (VIKI) study included 387 hemodialysis patients from 18 dialysis centers in Italy. We determined plasma levels of bone markers: vitamin K levels, VKDPs, vitamin 25(OH)D, alkaline phosphatase (ALP), parathyroid hormone (PTH), calcium (Ca), phosphorus (P) and routine biochemistry. BMI was classified into the following categories: underweight (BMI < 18.5 kg/m²), normal weight (18.5 ≤ BMI < 25 kg/m²), overweight (25 ≤ BMI < 30 kg/m²) and obese (BMI ≥ 30 kg/m²).

RESULTS

45.2% of patients were overweight or obese. Stratification by BMI demonstrated lower median menaquinone-7 (MK7)/triglycerides levels in obese patients (0.42 ng/mg [0.19, 0.87], p = 0.005). BGP levels were lower in overweight and obese patients (152 mcg/L [83.2, 251] and 104 mcg/L [62.7, 230], p = <0.001). Furthermore, there was an inverse correlation between MK7/triglycerides levels and BMI (regression coefficient β = -0.159; p = 0.003). In multiple linear regression, there was an inverse relationship between BGP levels and BMI (β = - 0.119; p = 0.012).

CONCLUSIONS

These data are the first to report an inverse relationship between Vitamin K2 levels and BMI in hemodialysis patients. Further studies are needed to confirm these findings and to determine if lower levels of Vitamin K are related to greater morbidity and mortality in this at-risk population.