Prevalence and predictors of abdominal aortic calcification in healthy living kidney donors

Vascular calcification in kidney stone formers: the impact of age and stone composition

An increased prevalence of vascular calcification (VC) has been reported in kidney stone formers (KSFs), along with an elevated cardiovascular risk. The aim of the current study is to assess whether VC in these patients develops at a younger age and is influenced by stone composition. This single-center, matched case-control study included KSFs with uric acid or calcium oxalate stones (diagnosed based on stone analysis) and age- and sex-matched controls without a history of nephrolithiasis. The prevalence and severity of abdominal aortic calcification (AAC) and bone mineral density (BMD) were compared between KSFs and non-KSFs. In total, 335 patients were investigated: 134 with calcium oxalate stones, 67 with uric acid stones, and 134 controls. Overall, the prevalence of AAC was significantly higher among calcium stone formers than among the controls (67.9% vs. 47%, p = 0.002). In patients under 60 years of age, those with calcium oxalate stones exhibited both a significantly elevated AAC prevalence (61.9% vs. 31.3%, p = 0.016) and severity (94.8 ± 15.4 vs. 30.3 ± 15.95, p = 0.001) compared to the controls. Within the age group of 40-49, osteoporosis was identified only in the KSFs. Multivariate analysis identified age, smoking, and the presence of calcium stones as independent predictors of AAC. This study highlights that VC and osteoporosis occur in KSFs at a younger age than in non-stone-formers, suggesting potential premature VC. Its pathogenesis is intriguing and needs to be elucidated. Early evaluation and intervention may be crucial for mitigating the cardiovascular risk in this population.

The estimated glomerular filtration rate was U-shaped associated with abdominal aortic calcification in US adults: findings from NHANES 2013-2014

Objectives

The high incidence of abdominal aortic calcification (AAC) is well-documented in individuals with severe renal function decline. However, there is limited research on the historical relationship between estimated glomerular filtration rate (eGFR) and the risk of AAC occurrence in the general population undergoing routine medical examinations. The main objective of this study was to investigate the historical relationship between eGFR and AAC in the general population of the United States.

Methods

We performed a cross-sectional study using the National Health and Nutrition Examination Survey 2013-2014 database. Weighted multivariate linear regression models were used to estimate the associations of eGFR with AAC score. Smooth curve fitting and two-piecewise linear regression were employed to explore the potential non-linear relationship.

Results

A total of 2,978 participant (48.22% were male) aged 40-80 years were included in this study. The fully-adjusted model demonstrated a negative correlation between eGFR and AAC score (β = -0.015, 95% CI: -0.023 to -0.006). However, when applying the smooth curve fitting method, a U-shaped relationship was identified, and the inflection point was calculated at 76.43 ml/min/1.73 m2 using the two-piecewise linear regression model.

Conclusions

There was a U-shaped association between eGFR and AAC score in general US adults, with an inflection point at about 76.43 ml/min/1.73 m2.

Serum biomarkers for arterial calcification in humans: A systematic review

Aim

To clarify the role of mediators of ectopic mineralization as biomarkers for arterial calcifications.

Methods

MEDLINE and Embase were searched for relevant literature, until January 4th 2022. The investigated biomarkers were: calcium, phosphate, parathyroid hormone, vitamin D, pyrophosphate, osteoprotegerin, receptor activator of nuclear factor-kappa B ligand (RANKL), fibroblast growth factor-23 (FGF-23), Klotho, osteopontin, osteocalcin, Matrix Gla protein (MGP) and its inactive forms and vitamin K. Studies solely performed in patients with kidney insufficiency or diabetes mellitus were excluded.

Results

After screening of 8985 articles, a total of 129 articles were included in this systematic review. For all biomarkers included in this review, the results were variable and more than half of the studies for each specific biomarker had a non-significant result. Also, the overall quality of the included studies was low, partly as a result of the mostly cross-sectional study designs. The largest body of evidence is available for phosphate, osteopontin and FGF-23, as a little over half of the studies showed a significant, positive association. Firm statements for these biomarkers cannot be drawn, as the number of studies was limited and hampered by residual confounding or had non-significant results. The associations of the other mediators of ectopic mineralization with arterial calcifications were not clear.

Conclusion

Associations between biomarkers of ectopic mineralization and arterial calcification are variable in the published literature. Future longitudinal studies differentiating medial and intimal calcification could add to the knowledge of biomarkers and mechanisms of arterial calcifications.

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We researched the association between biomarkers and arterial calcifications.

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This review focused on biomarkers of bone metabolism and Matrix Gla protein.

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Associations between biomarkers and arterial calcification are variable.

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Future studies should differentiate between medial and intimal calcifications.

Vascular Calcification Is Associated with Fetuin-A and Cortical Bone Porosity in Stone Formers

Background: Nephrolithiasis has been associated with bone loss and vascular calcification (VC), reflecting abnormal extraosseous calcium deposition. Fetuin-A (Fet-A) acts as a potent inhibitor of ectopic mineralization. The aim of the present study was to evaluate the prevalence of VC in stone formers (SF) and non-stone formers (NSF) and to investigate potential determinants of VC among SF, including circulating levels of Fet-A and bone microarchitecture parameters. Methods: Abdominal aortic calcification (AAC) was assessed using available computed tomography in SF and in age-, sex-, and BMI-matched NSF (potential living kidney donors). Serum Fet-A was measured in stored blood samples from SF. Bone microarchitecture parameters were obtained as a post hoc analysis of a cross-sectional cohort from young SF evaluated by high-resolution peripheral quantitative computed tomography (HR-pQCT). Results: A total of 62 SF (38.0 [28.0−45.3] years old) and 80 NSF (40.0 [37.0−45.8] years old) were included. There was no significant difference in AAC scores between SF and NSF. However, when dividing SF according to mean AAC score, below <5.8% (n = 33) or above ≥5.8% (n = 29), SF with higher AAC presented significantly higher BMI and tibial cortical porosity (Ct.Po) and significantly lower serum HDL, klotho, Fet-A, and eGFR. Urinary calcium did not differ between groups, but fractional excretion of phosphate was higher in the former. Upon multivariate regression, BMI, serum Fet-A, and tibial Ct.Po remained independently associated with AAC. Conclusions: This study suggests an association between reduced circulating Fet-A levels and increased bone Ct.Po with VC in SF.

Measurement of Aortic Atherosclerotic Disease Severity: A Novel Tool for Simplified, Objective Disease Scoring Using CT Angiography

Introduction

Vascular calcification is a recognized indicator of cardiovascular morbidity and mortality. Calcium scoring is a widely used tool to measure coronary artery calcification, however has limitations for use elsewhere in the body. There is currently no gold standard for quantifying abdominal aortic calcification (AAC).

We propose a simple and reproducible method to assess the severity of AAC using multiplanar reconstruction (MPR) in CT angiograms (CTA).

Methods

A retrospective analysis of CTAs from 75 patients over two years was performed. Using a novel six-point scoring system, three radiologists independently scored the severity of AAC in the distal abdominal aorta. Interclass correlation (ICC) was used to assess the degree of agreement between the three raters.

Calcium scoring of the same region was also calculated for each patient. We used Spearman's rank correlation coefficient to compare the CT calcium score with the corresponding average rater's atheroma score.

Results

There was significant agreement between raters’ scores, with an ICC value = 0.972, 95% (CI 0.959-0.981, p < 0.0001). There was also a strong correlation between an average rater's atheroma score with the corresponding CT calcium score, rho = 0.85 (p < 0.0001).

Conclusion

The results show excellent reproducibility of scores between radiologists, as well as a strong correlation between this novel scoring tool and calcium scores, indicating that it is a reliable method for the grading of AAC. 

We propose that this simple semi-quantitative method could form a widely used system for AAC disease stratification.

The relationship between vascular calcifications and urolithiasis in a large, multiethnic patient population

Several studies have reported associations between vascular calcifications and urinary stone disease (USD). However, results have been inconsistent and the majority of studies did not report on race/ethnicity. We examined the association between vascular calcifications and USD in a large, racially/ethnically diverse patient population. We identified 672 USD cases and 672 controls (i.e., patients without a history of USD) from patients who underwent non-contrast CT imaging at Montefiore Medical Center in Bronx, New York between 2004 and 2013. Controls were matched to cases on age, sex and race/ethnicity. The non-contrast CT imaging was used to measure abdominal aortic calcification (AAC) and calculate the AAC severity score. Logistic regression models were used to examine associations of AAC presence and severity score with risks of USD and stone types. Cases and controls had similar AAC prevalence (45.2% vs. 44.8%, p = 0.87), and AAC severity score (median 10 vs. 9.3, p = 0.47). The presence of AAC (OR = 0.98, 95% CI 0.78-1.23; p = 0.86) or AAC severity score were not associated with risk of USD: ORs of 0.96, 0.87, 1.07 and 1.03 for increasing AAC quartiles (p-trend = 0.54). There were also no associations in the stratified analyses by race/ethnicity or by sex. However, when USD patients were stratified by stone type, brushite/apatite stone formers had an inverse association with the lowest quartile of AAC severity score (OR = 0.35, 95% CI 0.11-0.84, p = 0.04) in comparison to patients without AAC. Overall, we found no association between vascular calcifications and risk of urinary stone disease in this large, hospital-based, case-control study.

Impact of Abdominal Aortic Calcification Among Liver Transplantation Recipients

Abdominal aortic calcification (AAC) is known as a risk factor of coronary artery disease, stroke, hyperphosphatemia, chronic inflammation, diabetes, and decreased estimated glomerular filtration rate. However, the clinical implications of incidental AAC findings in liver transplantation (LT) have not been evaluated in terms of posttransplantation survival and complications. Therefore, we analyzed the relationships between the AAC level and the outcomes following LT. A total of 156 consecutive patients who underwent LT between January 2007 and December 2014 were divided into 2 groups according to their AAC level (<100 mm³ or ≥100 mm³ ), as calculated using the Agatston method. Even after propensity matching, the survival time was significantly longer in the low-AAC group compared with that in the high-AAC group (median survival time, 4.5 versus 3.0 years; P < 0.01). A multivariate analysis identified high AAC level (hazard ratio, 2.2) and old donor age (hazard ratio, 2.2) as prognostic factors for overall survival. In conclusion, high AAC is an independent unfavorable prognostic factor in LT.

Diabetes and Abdominal Aortic Calcification-a Systematic Review

PURPOSE OF REVIEW

A systematic literature review was performed to evaluate diabetes mellitus (DM) as a risk factor of abdominal aortic calcification (AAC), and address factors that might contribute to the development of AAC in DM patients.

RECENT FINDINGS

DM is an independent risk factor of AAC development. Bone metabolism along with lifestyle factors among DM patients makes them more prone to AAC. Hip and vertebral fractures, high phosphate, smoking, hypertension, and low osteocalcin could make DM patients prone to AAC. Low levels of high-density lipoprotein (HDL), high low-density lipoprotein (LDL), high total cholesterol/HDL ratio, low bone mineral density (BMD) may be risk factors, but the literature is more ambiguous. Body mass index (BMI) does not appear to increase risk of AAC. High phosphate levels and low osteocalcin levels seem to be biomarkers of AAC in patients with diabetes. However, the association between DM and AAC is complicated.

Prevalence of abdominal artery calcification in dialysis patients with end-stage renal disease: a systematic review and meta-analysis

PURPOSE

To systematically determine the prevalence of abdominal artery calcification (AAC) in dialysis patients with end-stage renal disease (ESRD) and identify reasons for heterogeneity.

METHODS

We searched PubMed, EMBASE, and Web of Science from database inception to March 2017. Cross-sectional or cohort (only used baseline data) studies reporting estimates of AAC prevalence in dialysis adult patients with ESRD were included. We performed a random-effects meta-analysis to generate pooled prevalence estimates. Subgroup analyses were used to compare differences within categorical variables (geographic region, AAC detection instruments, dialysis methods, study design, and sample size), and meta-regression analyses to assess the impact of continuous variables (participants' age, duration of dialysis, and male proportion).

RESULTS

A total of 44 studies with 9883 dialysis patients were included. The pooled prevalence for AAC was 68.5% (95% CI 63-73.9%). Subgroup analyses suggested that AAC prevalence varied significantly by geographical region and AAC detection instruments, not by dialysis methods, study design and sample size. Meta-regression analysis suggested that positive correlations were found between AAC prevalence and the age of participants as well as the male proportion (r = 1.01477, P = 0.002 and r = 2.034413, P = 0.01, respectively), but not with the duration of dialysis (P = 0.576).

CONCLUSION

The pooled and nearest estimate of AAC prevalence among dialysis patients was as high as 65%. Geographical region, AAC detection instruments, age of participants, and male proportion potentially lead to the high variance of the reported prevalence. Considering the high AAC prevalence, effective treatment for preventing vascular calcification in these patients is badly needed.

Abdominal aortic calcification in patients with CKD

Background

Abdominal aortic calcification (AAC) is independently associated with cardiovascular events in dialysis patients and in the general population. However, data in non-dialysis chronic kidney disease (CKD) patients are limited. We analyzed determinants and prognostic value of AAC in non-dialysis CKD patients.

Methods

We included patients with CKD not receiving renal replacement therapy from the MASTERPLAN study, a randomized controlled trial that started in 2004. In the period 2008–2009, an X-ray to evaluate AAC was performed in a subgroup of patients. We studied AAC using a semi-quantitative scoring system by lateral lumbar X-ray. We used baseline and 2-year data to find determinants of AAC. We used a composite cardiovascular endpoint and propensity score matching to evaluate the prognostic value of AAC.

Results

In 280 patients an X-ray was performed. In 79 patients (28 %) the X-ray showed no calcification, in 62 patients (22 %) calcification was minor (<4), while 139 patients (50 %) had moderate or heavy calcification (≥4). Older age, prior cardiovascular disease, higher triglyceride levels, and higher phosphate levels were independent determinants of a calcification score ≥4. AAC score ≥4 was independently associated with cardiovascular events, with a hazard ratio of 5.5 (95 % confidence interval 1.2–24.8).

Conclusions

Assessment of AAC can identify CKD patients at higher cardiovascular risk, and may provide important information for personalized treatment. Whether this approach will ultimately translate into better outcomes remains to be answered.

Electronic supplementary material

The online version of this article (doi:10.1007/s40620-015-0260-7) contains supplementary material, which is available to authorized users.

Vascular calcification and bone mineral density in recurrent kidney stone formers

BACKGROUND AND OBJECTIVES

Recent epidemiologic studies have provided evidence for an association between nephrolithiasis and cardiovascular disease, although the underlying mechanism is still unclear. Vascular calcification (VC) is a strong predictor of cardiovascular morbidity and the hypothesis explored in this study is that VC is more prevalent in calcium kidney stone formers (KSFs). The aims of this study were to determine (1) whether recurrent calcium KSFs have more VC and osteoporosis compared with controls and (2) whether hypercalciuria is related to VC in KSFs.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

This is a retrospective, matched case-control study that included KSFs attending an outpatient nephrology clinic of the Royal Free Hospital (London, UK) from 2011 to 2014. Age- and sex-matched non-stone formers were drawn from a list of potential living kidney donors from the same hospital. A total of 111 patients were investigated, of which 57 were KSFs and 54 were healthy controls. Abdominal aortic calcification (AAC) and vertebral bone mineral density (BMD) were assessed using available computed tomography (CT) imaging. The prevalence, severity, and associations of AAC and CT BMD between KSFs and non-stone formers were compared.

RESULTS

Mean age was 47±14 years in KSFs and 47±13 in non-stone formers. Men represented 56% and 57% of KSFs and non-stone formers, respectively. The prevalence of AAC was similar in both groups (38% in KSFs versus 35% in controls, P=0.69). However, the AAC severity score (median [25th percentile, 75th percentile]) was significantly higher in KSFs compared with the control group (0 [0, 43] versus 0 [0, 10], P<0.001). In addition, the average CT BMD was significantly lower in KSFs (159±53 versus 194 ±48 Hounsfield units, P<0.001). A multivariate model adjusted for age, sex, high BP, diabetes, smoking status, and eGFR confirmed that KSFs have higher AAC scores and lower CT BMD compared with non-stone formers (P<0.001 for both). Among stone formers, the association between AAC score and hypercalciuria was not statistically significant (P=0.86).

CONCLUSIONS

This study demonstrates that patients with calcium kidney stones suffer from significantly higher degrees of aortic calcification than age- and sex-matched non-stone formers, suggesting that VC may be an underlying mechanism explaining reported associations between nephrolithiasis and cardiovascular disease. Moreover, bone demineralization is more prominent in KSFs. However, more data are needed to confirm the possibility of potentially common underlying mechanisms leading to extraosseous calcium deposition and osteoporosis in KSFs.