Mineral and Bone Disorder and Its Association with Cardiovascular Parameters in Chinese Patients with Chronic Kidney Disease

Excess risk of cardiovascular events in patients in the United States vs. Japan with chronic kidney disease is mediated mainly by left ventricular structure and function

While patients receiving dialysis therapy in the United States are more likely to develop cardiovascular disease (CVD) than those in Japan, direct comparisons of patients with predialysis chronic kidney disease (CKD) are rare. To study this, we compared various outcomes in patients with predialysis CKD using data from the Chronic Renal Insufficiency Cohort (CRIC) and CKD Japan Cohort (CKD-JAC) studies and determined mediators of any differences. Candidate mediators included left ventricular (LV) indices assessed by echocardiography. Among 3125 CRIC and 1097 CKD-JAC participants, the mean LV mass index (LVMI) and ejection fraction (EF) were 55.7 and 46.6 g/m2 and 54% and 65%, respectively (both significant). The difference in body mass index (32 and 24 kg/m2, respectively) largely accounted for the differences in LVMI and C-reactive protein levels across cohorts. Low EF and high LVMI were significantly associated with subsequent CVD in both cohorts. During a median follow-up of five years, CRIC participants were at higher risk for CVD (adjusted hazard ratio [95% confidence interval]: 3.66 [2.74-4.89]) and death (4.69 [3.05-7.19]). A three-fold higher C-reactive protein concentration and higher phosphate levels in the United States cohort were moderately strong mediators of the differences in CVD. However, echocardiographic parameters were stronger mediators than these laboratory measures. LVMI, EF and their combination mediated the observed difference in CVD (27%, 50%, and 57%, respectively) and congestive heart failure (33%, 62%, and 70%, respectively). Thus, higher LV mass and lower EF, even in the normal range, were found to be predictive of CVD in CKD.

Management of Hyperphosphatemia in End-Stage Renal Disease: A New Paradigm

Bone and mineral metabolism becomes dysregulated with progression of chronic kidney disease (CKD), and increasing levels of parathyroid hormone serve as an adaptive response to maintain normal phosphorus and calcium levels. In end-stage renal disease, this response becomes maladaptive and high levels of phosphorus may occur. We summarize strategies to control hyperphosphatemia based on a systematic literature review of clinical trial and real-world observational data on phosphorus control in hemodialysis patients with CKD-mineral bone disorder (CKD-MBD). These studies suggest that current management options (diet and lifestyle changes; regular dialysis treatment; and use of phosphate binders, vitamin D, calcimimetics) have their own benefits and limitations with variable clinical outcomes. A more integrated approach to phosphorus control in dialysis patients may be necessary, incorporating measurement of multiple biomarkers of CKD-MBD pathophysiology (calcium, phosphorus, and parathyroid hormone) and correlation between diet adjustments and CKD-MBD drugs, which may facilitate improved patient management.

Utilization of antihypertensive drugs among chronic kidney disease patients: Results from the Chinese cohort study of chronic kidney disease (C-STRIDE)

The utilization of antihypertensive drugs plays an important role in blood pressure control among chronic kidney disease (CKD) patients. Limited information was available on how antihypertensive drugs were used among Chinese CKD patients. In the present study, the utilization of antihypertensive drugs among a subgroup of hypertensive participants with a complete record of antihypertensive drug information from the Chinese Cohort Study of Chronic Kidney Disease was analyzed. Among 2213 subjects, 61.7% and 26.5% had their blood pressure controlled to <140/90 mmHg and <130/80 mmHg, respectively. In total, 38.5% were on monotherapy. Of those patients who received combination therapy, 57.8% were treated with a two-drug combination. Renin-angiotensin system inhibitors (RASIs) were the most commonly prescribed drugs (71.2%). Only 10.2% of the patients were prescribed diuretics. After multivariable adjustment, participants taking RASI were more likely to have their blood pressure controlled to <140/90 mmHg (prevalence ratio (PR) 1.153, 95% confidence interval (CI): 1.071-1.240). CKD stage 4 (PR 0.548, 95% CI: 0.434-0.692) was associated with RASIs treatment. Additionally, diabetes (PR 1.498, 95% CI: 1.120-2.004), albumin/creatinine ratio ≥300 mg/g (PR 1.547, 95% CI: 1.020-2.344), and CKD stage 4 (PR 2.022, 95% CI: 1.223-3.343) were associated with diuretic use. The results suggested that combination therapy, diuretics use in general, and utilization of RASIs in advanced CKD stage were insufficient in the current treatment of Chinese hypertensive CKD patients.

Inhibition of sodium/hydrogen exchanger 3 in the gastrointestinal tract by tenapanor reduces paracellular phosphate permeability

Hyperphosphatemia is common in patients with chronic kidney disease and is increasingly associated with poor clinical outcomes. Current management of hyperphosphatemia with dietary restriction and oral phosphate binders often proves inadequate. Tenapanor, a minimally absorbed, small-molecule inhibitor of the sodium/hydrogen exchanger isoform 3 (NHE3), acts locally in the gastrointestinal tract to inhibit sodium absorption. Because tenapanor also reduces intestinal phosphate absorption, it may have potential as a therapy for hyperphosphatemia. We investigated the mechanism by which tenapanor reduces gastrointestinal phosphate uptake, using in vivo studies in rodents and translational experiments on human small intestinal stem cell-derived enteroid monolayers to model ion transport physiology. We found that tenapanor produces its effect by modulating tight junctions, which increases transepithelial electrical resistance (TEER) and reduces permeability to phosphate, reducing paracellular phosphate absorption. NHE3-deficient monolayers mimicked the phosphate phenotype of tenapanor treatment, and tenapanor did not affect TEER or phosphate flux in the absence of NHE3. Tenapanor also prevents active transcellular phosphate absorption compensation by decreasing the expression of NaPi2b, the major active intestinal phosphate transporter. In healthy human volunteers, tenapanor (15 mg, given twice daily for 4 days) increased stool phosphorus and decreased urinary phosphorus excretion. We determined that tenapanor reduces intestinal phosphate absorption predominantly through reduction of passive paracellular phosphate flux, an effect mediated exclusively via on-target NHE3 inhibition.

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.

Path Analysis on Medical Expenditures of 855 Patients with Chronic Kidney Disease in a Hospital in Beijing

BACKGROUND

Investigate into the medical expenditures of chronic kidney disease (CKD) patients through path analysis method of three consecutive years within a Grade-A tertiary hospital in Beijing to conduct the main influencing factors in diagnosis-related groups (DRGs) grouping of the diagnosis, and reassess the present grouping process to provide information and reference on cost control for hospitals and medical management departments.

METHODS

Eight hundred and fifty-five inpatient cases whose first diagnosis were defined as CKD in the year 2014-2016 within the hospital were selected as the sample of the study, multiple linear regression and path analysis method were adopted in DRGs grouping process to investigate the main influencing factors of total medical expenditures and DRGs grouping process.

RESULTS

The maximum proportion of the medical costs within CKD patients was the costs on treatment, with the highest of 35.3% on the year 2014, the second was the costs on drug, which accounted for <30% during consecutive years, and the third was the costs on examination, which accounted for about 20% on average. The main influencing factors of medical expenditures included the type of dialysis, length of hospitalization, the admission of Intensive Care Unit (ICU), and so on. The coefficients toward the effect for total costs were 0.416, 0.376, and 0.094, respectively.

CONCLUSIONS

It is suggested that the type of dialysis and the admission of ICU were the major influencing factors of inpatient medical expenditures on CKD patients, and should be taken into consideration into the reassessment of DRGs grouping process to realize the localization and generalization of prospective payment system based on DRGs within the regional area and promote the implementation of medical cost control measures to reduce the economic burdens among patients and the society.