What can we learn from a statistically inconclusive trial? Consensus conference on the EVOLVE study results.

The link between serum parathyroid hormone (iPTH) and cardiovascular (CVS) mortality has not been fully elucidated. The EVOLVE Study was designed to test whether a drug such as cinacalcet, aimed at lowering iPTH, could reduce the astonishingly high cardiovascular risk in patients on maintenance dialysis (CKD-5D). Accordingly, the primary outcome of the study was the combined endpoint of time to death or hospitalization due to CVS factors or from any cause. Time to bone fracture and parathyroidectomy were regarded as secondary endpoints. At study completion, the Intention-To-Treat analysis documented a non- significant 7% (Hazard Ratio: 0.93; 95% Confidence interval: 0.85-1.02; P = 0.11) reduction of the primary composite endpoint. However, the intention to treat analysis does not take into account adherence to drug regimens or control for factors that may potentially jeopardize the conduction of the study. In particular, in spite of a careful pre-planned study sample calculation, the final power of the EVOLVE study was 54% instead of the assumed 90%, greatly reducing the reliability of study results. Furthermore, the pre-planned multivariable adjustment of the primary endpoint suggests a nominally significant reduction of the risk of the primary composite endpoint when age is entered into the statistical model. The sensitivity analysis further corroborates this result. The Lag Time Censoring Analysis (LTCA) evidenced a nominally significant 15% risk reduction of the composite endpoint among patients allocated to cinacalcet if the patients follow-up was terminated 6 months after the study drug discontinuation, as pre-planned in the protocol. It is interesting that the LTCA suggests that the effect of cinacalcet weakened over time and became insignificant after about 1 year from drug discontinuation. Although authors could not detect any effect of cinacalcet on bone fracture associated with cinacalcet use, the secondary analyses of the EVOLVE trial suggest a nominally significant 60-70% risk reduction of parathyroidectomy and a reassuring safety profile of prolonged exposure to cinacalcet. In summary, the EVOLVE study adds to the list of inconclusive randomized clinical trials in Nephrology. However, the preplanned exploratory and sensitivity analyses suggest that when imbalances of patients characteristics at study entry (i.e. age) or study drug discontinuation are considered, a 'nominally' significant risk reduction in CVS and parathyroidectomy associated with cinacalcet treatment is noted.

Gadolinium-associated nephrogenic systemic fibrosis: the need for nephrologists' awareness.

Nephrogenic systemic fibrosis (NSF) / nephrogenic fibrosing dermopathy (NFD) is a recently described disease, occurring only in patients with variable degrees of renal failure (RF) previously exposed to gadolinium-based contrast agents (GBCAs) for magnetic resonance imaging. Public advisories are consistent on some key points including that no cases of NSF/NFD have been reported in patients with normal renal function, and GBCAs may be toxic in patients with RF due to the prolongation of the half-time allowing dissociation and extravasation of highly toxic gadolinium-free ions, potentially linked to the scleroderma-like NSF/NFD, a systemic disabling disease with a mortality rate of up to 30%. The most intriguing feature remains which cofactor might be at play to explain why the disease occurs only in a minority of exposed patients. Therefore, renal dysfunction (substrate) and gadolinium chelates (trigger agent) are necessary but not sufficient. The challenge for nephrologists includes (a) evidence of transmetallation, such as gadolinium deposits in bone, increased urinary zinc excretion, iron-transferrin dissociation or "spurious hypocalcemia" in exposed people; (b) research for uremic cofactors such as increased serum calcium/phosphate, acidosis, use of phosphate-chelating agents able to act as efficient competitor ligands or other drugs; and (c) identification of at-risk patients (with moderate to severe renal dysfunction) and definition of the role of dialysis in removing gadolinium chelates, if any. Nephrologists are called to action to collect and organize information to identify cofactors for NSF/NFD, and therefore they must be aware of this new pathology, as the eye sees only what the mind knows.