Pulse wave velocity measurements are reproducible in multiple trained observers: a short report.

BACKGROUND: Arterial stiffness, measured by pulse wave velocity (PWV), is highly predictive of mortality in dialysis patients. As such, PWV is frequently used in clinical research studies and may have a role in clinical practice if shown to be suitably reliable. Measurement of PWV using the SphygmoCor system is known to be an observer-dependent technique. The aim of this study was to investigate the ability of 4 observers to acquire reproducible PWV and pulse wave analysis (PWA) measurements after a 6-week training period. METHODS: Reproducibility of this technique was investigated using repeated measurements of the carotid-femoral PWV and PWA of the radial pulse by the 4 observers after a period of training. Both healthy volunteers and individuals with chronic kidney disease (CKD) were recruited for this study. Measurements were considered to have met quality control if 2 consecutive measurements were visually acceptable, within 1.5 m/s of each other and had a standard deviation of less than 10%. A fixed-effect analysis of variance was used to test the variation in measurements between the observers; the intraclass correlation coefficient (ICC) was used to assess the statistical agreement between the observers. RESULTS: A total of 20 individuals volunteered for PWV and PWA measurements (13 with CKD and 7 without); the mean age was 58 years (range 24-83). The average PWV was 9.4 +/- 3.6 m/s. There was no significant difference shown between the 4 observers' measurements (p = 0.25). Further, there was good statistical agreement between the observers (ICC = 0.95). CONCLUSIONS: After a period of training it is possible for multiple observers to have reproducible measurements of PWV and PWA. Assurance of reproducibility is important when more than one individual is collecting data in a study, particularly when assessing changes over time.

Early initiation of phosphate lowering dietary therapy in non-dialysis chronic kidney disease: a critical review.

Dietary management of hyperphosphatemia and hyperparathyroidism have long been important elements in the clinical management of CKD stage 4 and 5 for the prevention of mineral bone disease. The rationale for phosphate lowering has been further justified, given the accumulating data to support the association of phosphate with vascular damage, in this population who are at high risk of cardiovascular (CV) death. Phosphate is a novel CV risk factor in both CKD and in the general population, and a growing body of literature suggests that high normal serum phosphate may be a risk factor for progression of CKD. Few studies have examined hard outcomes after phosphate lowering. Nonetheless, given the balance of data both in cell, animal and human studies, the use of phosphate lowering strategies at earlier stages of CKD, perhaps even prior to serum phosphate level rising, may well be justified. This review will discuss the complications associated with higher serum phosphate, the potential benefits of early phosphate intervention, practical considerations of low phosphate diets and novel strategies for evaluating these strategies in clinical practice.