Where is the link between mineral bone markers and cardiovascular disease in CKD?

The Impact of Antihypertensive Medications on Bone Mineral Density and Fracture Risk

PURPOSE OF REVIEW

This review summarizes the impact of thiazide diuretics on fracture risk in older hypertensive individuals.

RECENT FINDINGS

We performed a post hoc evaluation of the Antihypertensive and Lipid-Lowering Treatment to Prevent Heart Attack Trial, a randomized, prospective, double blind hypertension study comparing a thiazide-like diuretic, a calcium channel blocker (CCB), and an angiotensin converting enzyme inhibitor (ACEi). We examined the risk of hip and pelvic fractures during the in-trial period (n = 22,180 participants; mean 4.9-year follow-up) and during the post-trial period using national data bases (n = 16,622 participants) (mean total follow-up 7.8 years). During the trial, participants randomized to the thiazide diuretic versus the CCB or the ACEi had a lower risk of fracture on adjusted analyses (HR 0.79 [95% CI, 0.63, 0.98], p = 0.04). Risk of fracture was significantly lower in participants randomized to the diuretic as compared to those randomized to the ACEi (HR 0.75 [95% CI, 0.58, 0.98]; p = 0.04), but not significantly different compared to the CCB (HR 0.87 [95% CI, 0.71, 1.09]; p = 0.17). Over the entire trial and post-trial period of follow-up, the cumulative incidence of fractures was non-significantly lower in participants assigned to the diuretic vs assignment to the ACEi or the CCB (HR 0.87 [0.74-1.03], p = 0.10) and versus each medication separately. These findings establish a benefit for thiazide diuretic treatment for the prevention of fractures versus other commonly used antihypertensive medications using prospective, randomized data. The effects of the thiazide diuretic on bone appear to be long lasting.

Positioning novel biologicals in CKD-mineral and bone disorders

Renal osteodystrophy (ROD), the histologic bone lesions of chronic kidney disease (CKD), is now included in a wider syndrome with laboratory abnormalities of mineral metabolism and extra-skeletal calcifications or CKD-mineral and bone disorders (CKD-MBD), to highlight the increased burden of mortality. Aging people, frequently identified as early CKD, could suffer from either the classical age-related osteoporosis (OP) or ROD. Distinguishing between these two bone diseases may not be easy without bone biopsy. In any case, besides classical therapies for ROD, nephrologists are now challenged by the possibility of using new drugs developed for OP. Importantly, while therapies for ROD mostly aim at controlling parathyroid secretion with bone effects regarded as indirect, new drugs for OP directly modulate bone cells activity. Thus, their action could be useful in specific types of ROD. Parathyroid hormone therapy, which is anabolic in OP, could be useful in renal patients with low turnover bone disease. Denosumab, the monoclonal antibody against receptor activator of NF-κB ligand (RANK-L) that inhibits osteoclast activity and proliferation, could be beneficial in cases with high turnover bone. Use of romosozumab, the monoclonal antibody against sclerostin, which both stimulates osteoblasts and inhibits osteoclasts, could allow both anabolic and anti-resorptive effects. However, we should not forget the systemic role now attributed to CKD-MBD. In fact, therapies targeting bone cells activity could also result in unpredicted extra-bone effects and affect cardiovascular outcomes. In conclusion, the new biologicals established for OP could be useful in renal patients with either OP or ROD. In addition, their potential non-bone effects warrant investigation.

Imaging for Vascular Calcification

Chronic decline in renal function is accompanied by deterioration of bone structure and function and progressive calcification of the vascular system. Both disease states have been linked with increased morbidity and mortality in chronic kidney disease. The severe alterations of mineral metabolism inherent with loss of renal function have an impact on vascular calcification development and progression, and several investigators have focused on ways to reduce their impact on vascular health. Imaging has contributed an important role in the assessment of vascular calcification, and the impact of various interventions aimed at curbing their progression.

Cardiovascular calcifications in chronic kidney disease: Potential therapeutic implications

Cardiovascular (CV) calcification is a highly prevalent condition at all stages of chronic kidney disease (CKD) and is directly associated with increased CV and global morbidity and mortality. In the first part of this review, we have shown that CV calcifications represent an important part of the CKD-MBD complex and are a superior predictor of clinical outcomes in our patients. However, it is also necessary to demonstrate that CV calcification is a modifiable risk factor including the possibility of decreasing (or at least not aggravating) its progression with iatrogenic manoeuvres. Although, strictly speaking, only circumstantial evidence is available, it is known that certain drugs may modify the progression of CV calcifications, even though a direct causal link with improved survival has not been demonstrated. For example, non-calcium-based phosphate binders demonstrated the ability to attenuate the progression of CV calcification compared with the liberal use of calcium-based phosphate binders in several randomised clinical trials. Moreover, although only in experimental conditions, selective activators of the vitamin D receptor seem to have a wider therapeutic margin against CV calcification. Finally, calcimimetics seem to attenuate the progression of CV calcification in dialysis patients. While new therapeutic strategies are being developed (i.e. vitamin K, SNF472, etc.), we suggest that the evaluation of CV calcifications could be a diagnostic tool used by nephrologists to personalise their therapeutic decisions.