Do indicators of dialysis 'quality' agree?.

Aim: Examine agreement between various indicators of dialysis 'quality'. Background(s): There has been considerable discussion about markers of dialysis 'quality'. The extent of agreement between these in Australian units in not known. Method(s): From the ANZDATA Registry, units were ranked (in a deidentified fashion) by a number of criteria including size, achievement of various dialysis parameters including HD access, peritonitis rates, biochemical parameters etc. Consistency among rankings from various markers was then compared internally between various markers. Markers were also a compared with achieved unit mortality (adjusted for covariates) as the 'gold standard'. The consistency of unit rankings over time was also examined. Result(s): Overall, there was poor agreement between rankings derived from various measures. Specifically, rankings derived from peritonitis rate did not statistically correlate with those of use of central venous catheters (CVC) at first haemodialysis (r = 0.14, p = 0.28); neither peritonitis rate (r = 0.05, p = 0.7) nor CVC ranking (r = 0.10, p = 0.42) correlated with that based on longer term mortality. There was also little indicators of agreement with rankings based on achievement of phosphate or haemoglobin targets, unit size or number of preemptive kidney transplants. Within units, peritonitis rates and CVC rates (and therefore) rankings did fluctuate from year to year especially for smaller units. Among 74 units, the overall standard deviation (over 5 years) for rankings for peritonitis was 17 and for CVC use 13. Conclusion(s): There is poor agreement among markers proposed for measurement of dialysis 'quality'. This underlines the complexity of assessment of performance of dialysis units. Rates of line use and peritonitis (and therefore rankings) fluctuate over time; this will reflect components of statistical variation (especially for smaller units and real changes in practice).